Aquatic products are extremely perishable food commodities. Developing methods to keep the freshness of fish represents a major task of the fishery processing industry. Application of Lactic Acid Bacteria(LAB) as food...Aquatic products are extremely perishable food commodities. Developing methods to keep the freshness of fish represents a major task of the fishery processing industry. Application of Lactic Acid Bacteria(LAB) as food preservative is a novel approach. In the present study, the possibility of using lactic acid bacteria in freshness keeping of tilapia fillets as sashimi was examined. Fish fillets were dipped in Lactobacillus plantarum 1.19(obtained from China General Microbiological Culture Collection Center) suspension as LAB-treated group. Changes in K-value, APC, sensory properties and microbial flora were analyzed. Results showed that LAB treatment slowed the increase of K-value and APC in the earlier storage, and caused a smooth decrease in sensory score. Gram-negative bacteria dominated during refrigerated storage, with Pseudomonas and Aeromonas being relatively abundant. Lactobacillus plantarum 1.19 had no obvious inhibitory effect against these Gram-negatives. However, Lactobacillus plantarum 1.19 changed the composition of Gram-positive bacteria. No Micrococcus were detected and the proportion of Staphylococcus decreased in the spoiled LAB-treated samples. The period that tilapia fillets could be used as sashimi material extended from 24 h to 48 h after LAB treatment. The potential of using LAB in sashimi processing was confirmed.展开更多
Bacterial community presumably plays an essential role in inhibiting pathogen colonization and maintaining the health of scallop larvae, but limiting data are available for Yesso scallop （Patinopecten yessoensisis Ja...Bacterial community presumably plays an essential role in inhibiting pathogen colonization and maintaining the health of scallop larvae, but limiting data are available for Yesso scallop （Patinopecten yessoensisis Jay, 1857） larval development stages. The aim of this study was to characterize and compare the bacterial communities associating with Yesso scallop larval development at fertilized egg S l, trochophora S2, D-shaped larvae S3, umbo larvae S4, and juvenile scallop S5 stages by Illumina high-throughput sequencing. Genomic DNA was extracted from the larvae and their associating baetera, and a gene segment covering V3-V4 region of 16S rRNA gene was amplified and sequenced using an Illumina Miseq sequencer. Overall, 106760 qualified sequences with an average length of 449 bp were obtained. Sequences were compared with those retrieved from 16S rRNA gene databases, and 4 phyla, 7 classes, 15 orders, 21 families, 31 genera were identified. Proteobacteria was predominant phylum, accounting for more than 99%, at all 5 larval development stages. At genus level, Pseudomonas was dominant at stages S1 （80.60%）, S2 （87.77%） and S5 （68.71%）, followed by Photobacterium （17.06%） and Aeromonas （1.64%） at stage S1, Serratia （6.94%）, Stenotrophomonas （3.08%） and Acinetobacter （1.2%） at stage S2, Shewanella （25.95%） and Pseudoalteromonas （4.57%） at stage S5. Moreover, genus Pseudoal- teromonas became dominant at stages S3 （44.85%） and S4 （56.02%）, followed by Photobacterium （29.82%）, Pseudomonas （11.86%）, Aliivibrio （8.60%） and Shewanella （3.39%） at stage S3, Pseudomonas （18.16%）, Aliivibrio （14.29%）, Shewanella （4.11%）, Psychro- monas （4.04%） and Psychrobacter （1.81%） at stage S4. From the results, we concluded that the bacterial community changed sig- nificantly at different development stages of Yesso Scallop larvae.展开更多
Strain E1 with resistance to 18 mmol/L cadmium （Cd）, isolated from Cd-contaminated soil was identified by morphological observation, biochemical and physiological characterization and 16S rDNA sequence analysis. The...Strain E1 with resistance to 18 mmol/L cadmium （Cd）, isolated from Cd-contaminated soil was identified by morphological observation, biochemical and physiological characterization and 16S rDNA sequence analysis. The resistance to heavy metals Cd, Cu, Co, Mn, Pb, Zn and 12 antibiotics was examined. The ability of removing Cd from solution was studied. The characterizations show that strain El is affiliated to Pseudomonas aeruginosa （P aeruginosa）. Strain E1 has high resistance to heavy metals and the order is found to be Cd〉Mn〉Zn〉Cu〉Pb〉Co in solid media. Strain E1 also exhibits the resistance to 12 antibiotics. Both living and non-living cells of strain E1 can remove Cd from solution, and living cell has better biosorption than non-living cell.展开更多
The present study identified the properties of porins in the outer membrane in Pseudomonas aeruginosa,and showed the role of outer membrane in determining imipenem diffusion in Pseudomonas a...The present study identified the properties of porins in the outer membrane in Pseudomonas aeruginosa,and showed the role of outer membrane in determining imipenem diffusion in Pseudomonas aeruginosa The molecular weight of the major outer membrane protein was analyzed by SDS PAGE The purification of the porins in Pseudomonas aeruginosa was achieved by DEAE ion exchange HPLC The purified outer membrane proteins were reconstituted with phosphatidylcholine and dicetylphosphate into membrane vesicles, and were tested by the liposomes swelling method for the diffusion of imipenem The permeability assay showed that OprC (70 kD), OprD 2 (46kD), and OprE(43 kD) were the channel forming proteins But only OprD 2 was thought to be the likely route of imipenem diffusion展开更多
Seaweeds are known to exhibit various antimicrobial properties, since it harbours an enormous range of indigenous bioactive compounds. The emergence of drug resistant strains has directed to the identification of pros...Seaweeds are known to exhibit various antimicrobial properties, since it harbours an enormous range of indigenous bioactive compounds. The emergence of drug resistant strains has directed to the identification of prospective metabolites from seaweed and its endophytes, thereby exploiting the properties in resisting bacterial diseases. The current study was aimed to assess the antimicrobial activity of extracts obtained from Ulva reticulate, for which metabolites of Ulva reticulata and its endophytes were extracted and assessed against human pathogens like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Bacillus subtilis. It was observed that the hexane extract of isolate VITDSJ2 was effective against all the tested pathogens but a significant inhibition was observed for Staphylococcus aureus and Escherichia coli. Further, Gas chromatography coupled with Mass spectroscopy （GC-MS） revealed the existence of phenol, 3, 5-bis （1, 1-dimethylethyl） in the crude hexane extract which is well-known to possess antibacterial activity. The effective isolate VITDSJ2 was identified to be the closest neighbour of Pseudomonas smtzeri by phenotypic and genotypic methods. The crude extracts of the seaweed Ulva reticulata was also screened for antibacterial activity and the hexane extract was effective in showing inhibition against all the tested pathogens. The compound in the crude extract of Ulva reticulata was identified as hentriacontane using GC-MS. The extracts obtained from dichloromethane did not show significant activity in comparison with the hexane extracts. Hence the metabolites of Ulva reticulata and the bacterial secondary metabolites of the endophytes could be used in the treatment of bacterial infections.展开更多
A bacterial strain of the genus Pseudomonas aeruginosa was inoculated into a hydrocarbon culture medium and incubated for a definite period of time. The ability of the bacterial strain to biodegrade a hydrocarbon, viz...A bacterial strain of the genus Pseudomonas aeruginosa was inoculated into a hydrocarbon culture medium and incubated for a definite period of time. The ability of the bacterial strain to biodegrade a hydrocarbon, viz. n-hexadecane, was evaluated through determining the hexadecane concentration in the inoculated culture medium on a gas chromatograph (GC). The effect of pH value on the degrading ability of the bacterial isolate and the impact of temperature on microbial growth were also explored. Test results showed that Pseudomonas aeruginosa was markedly effective in biodegrading n-hexadecane. Furthermore, the ability of Pseudomonas aeruginosa to biodegrade n-hexadecane was different at various pH values. Pseudomonas aeruginosa provided excellent degrading ability at a pH value of 7.0. The microbial cells of Pseudomonas aeruginosa increased with an increasing incubation duration at temperatures ranging from 28 ℃ to 35 ℃, and an exponential phase of microbial growth was observed.展开更多
Bioflotation represents one of the growing trends to enhance the selectivity of conventional flotation processes. It utilizes the micro-organisms to replace or to interact with the chemical reagents to increase the ga...Bioflotation represents one of the growing trends to enhance the selectivity of conventional flotation processes. It utilizes the micro-organisms to replace or to interact with the chemical reagents to increase the gap between surface properties of similar minerals and to enhance the separation selectivity. In this work, dolomite-phosphate separation was investigated using amphoteric collector （dodecyl-N-carboxyethyl-N-hyroxyethyl-imidazoline） in presence of bacteria. Two types of bacteria, Corynebacterium- diphtheriae-intermedius （CDI）, and Pseudomonas aeruginosa （PA）, were used. The collector-bacteria interaction was characterized by Fourier transform infra-red （FTIR）, frothing height and Zeta potential. The results show that the collector-bacteria interaction improves the flotation selectivity. Although, the PA positively affects the separation results, the CDI cannot lower the MgO to less than 1%. A phosphate content of 0.7% MgO and 31.77% P205 with a recovery of 68% at pH 11, 3.0 kg/t amphoteric collector, 4× 10^7 cells of PA is obtained.展开更多
Rhamnolipid production by Pseudomonas aeruginosa ATCC 9027 with waste frying oil as sole carbon source was studied using response surface method. Cultures were incubated in shaking flask with temperature, NO3- and Mg2...Rhamnolipid production by Pseudomonas aeruginosa ATCC 9027 with waste frying oil as sole carbon source was studied using response surface method. Cultures were incubated in shaking flask with temperature, NO3- and Mg2+ concentrations as the variables. Meanwhile, fed-batch fermentation experiments were conducted. The results show that the three variables are closely related to rhamnolipid production. The optimal cultivation conditions are of 6.4 g/L NaNO3 , 3.1 g/L MgSO4 at 32 ℃, with the maximum rhamnolipid production of 6.6 g/L. The results of fed-batch fermentation experiments show that feeding the oil in two batches can enhance rhamnolipid production. The best time interval is 72 h with the maximum rhamnolipid production of 8.5 g/L. The data are potentially useful for mass production of rhamnolipid on oil waste with this bacterium.展开更多
Algal blooms caused by eutrophication in fresh water are one of the major environmental problems in the world. Using biological methods to control algal growth, especially based on allelopathic inhibitory effects of a...Algal blooms caused by eutrophication in fresh water are one of the major environmental problems in the world. Using biological methods to control algal growth, especially based on allelopathic inhibitory effects of aquatic macrophytes on phytoplankton growth, have been received world-wide attention. In this study, the allelopathic activity of the invasive macrophyte, Eichhornia crassipes （water hyacinth）, on blue-green algae, Microcystis aeruginosa （PCC7806） was investigated using coexistence assay. Our results showed that water hyacinth had disparate effects on the growth ofM~ aeruginosa （PCC7806） under different initial algal densities. Under lower initial algal density （OD650 = 0.10 and OD650 = 0.05）, the algal growth was significantly inhibited by water hyacinth （inhibition ratio was 95.6% and 97.3%, respectively）. While it was stimulated at higher initial algal densities （OD650 = 0.20）. Water hyacinth inhibited the growth of algae mainly through its root system. Culture water from water hyacinth and aqueous methanol extracts from dry roots samples also showed inhibition effects on algal growth. The inhibition effects increased as the increase of crude extract concentration, suggest that water hyacinth may excrete inhibitory substances from root system and show allelopathic inhibitory potential to the growth ofM. aeruginosa.展开更多
One possible application for the excess of glycerol, which is an exceeding byproduct in biodiesel industry, was used as carbon and energy sources for bioproducts synthesis. This work aims to evaluate biosurfactant pro...One possible application for the excess of glycerol, which is an exceeding byproduct in biodiesel industry, was used as carbon and energy sources for bioproducts synthesis. This work aims to evaluate biosurfactant production from glycerol by Pseudomonas aeruginosa EQ 109 isolated from crude oil-contaminated soil. Factorial design 2^3 was utilized to optimize the amount of biosurfactant produced, by using pH （A）, initial biomass concentration （B）, and initial glycerol concentration （C） as independent factors. The experiments were carried out in flasks containing 100 mL of mineral medium. Biosurfactant production was monitored by increase of the emulsification of aviation kerosene （E24） and surface tension reduction （STr）. The results have shown that, at pH = 7.0, in order to increase E24, variables as B and C are the most influential, leading to a maximum value of E24 = 79%, as well as for an increase of GC （GCmax = 49%）. STR was the variable with the best correlation factor for the proposed linear model （R2=0.96） and its maximum value was 48%. Xfwas not significant to the model, although it was influenced by pH and C, with C = 40g/L （Xfmax = 4.56 g/L）.展开更多
Ruta genus is a member of the family Rutaceae that has been cultivated widely in many regions of the world because of its medicinal properties. In Tessala Mountain （Sidi Bel Abbes Country, North-Western of Algeria）,...Ruta genus is a member of the family Rutaceae that has been cultivated widely in many regions of the world because of its medicinal properties. In Tessala Mountain （Sidi Bel Abbes Country, North-Western of Algeria）, the Ruta genus commonly known by ＂fidjel＂ is represented by two species： Ruta Chalepensis L. and Ruta Montana （L.） L. frequently used by local population in a traditional treatment. The water-distilled essential oils from this species yielded 7.23% and 6.104% for Ruta chalepensis L. and Ruta montana （L.） L. respectively. The essential oil of Ruta montana （L.） L. showed a strong antibacterial activity against all bacterial strains tested （Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Mycobacterium kansasii ATCC ! 2478 and Mycobacterium vaccae ATCC 1548314） compared to Ruta chalepensis L. oils which have a moderate effect only on Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853. Therefor, the antibacterial properties of the essential oils of Ruta Chalepensis L. and Ruta Montana （L.） L. are now well established through this study and therefore could justify their future uses in the treatment of nosocomial infections.展开更多
Advanced material with antibacterial properties would be a promising way to improve the disinfection process in food plants. Our objective was to combine the bactericidal effect of TiO2 with the mechanical strength of...Advanced material with antibacterial properties would be a promising way to improve the disinfection process in food plants. Our objective was to combine the bactericidal effect of TiO2 with the mechanical strength of TiN coatings. A TiO2 rutile film was obtained after annealing of a supplied 316 stainless steel with a TiN coating. This TiO2 upperlayer displays a photocatalytic activity under UV light exposure. The substrates with the TiN coating and the TiO2 upperlayer are more hydrophobic than the 316 control. The adhesion of either Listeria or Pseudomonas, on 316-TIN is characterized by the presence of clusters of cells, while the oxidation of the TiN surface leads to a more hydrophilic layer where cells are individualized. After UV illumination of the adherent cells and subsequent growth, the residual bacterial population present on 316-TIO2 is lower than that present on the 316-TIN. The bactericidal effect is more important on Listeria than on Pseudomonas.展开更多
Biosurfactants were synthesized by Pseudomonas aeruginosa （P.A.）, using sugar cane molasses as carbon source. Assays were conducted in a shaker with agitation speed of 200 rpm, temperature of 38 ℃ and aeration rat...Biosurfactants were synthesized by Pseudomonas aeruginosa （P.A.）, using sugar cane molasses as carbon source. Assays were conducted in a shaker with agitation speed of 200 rpm, temperature of 38 ℃ and aeration ratio （Vm/Vf） of 0.4 and 0.6. A concentration of 3.0% was used for the carbon and energy source （molasses） and of 0.3% for the nitrogen source （NaNO3）. Samples were removed at regular times until 96 hours of cultivation. The reduction in surface tension was measured using the ring method; cell concentration was obtained by the dry mass and substrate consumption by the DNS method. The metabolite produced was extracted and quantified by the thioglycolic method. The results showed a maximum surface tension reduction of 46.57% after 60 h, 3.63 g/L of biomass after 8 h （μXmax =0.15 h^-1）, 79.60% of substrate consumption （μs= 0.67 h-1） and 4.47 g/L of rhamnolipid （μp=0.029 h^-1）.展开更多
A new Shift bases was synthesized by the reaction of p-dimetyl-amino-benzylaldehide and α-naftyl-amine. All synthesized compounds were characterized by elemental analysis, IR （infra red） spectroscopy and NMR （nucl...A new Shift bases was synthesized by the reaction of p-dimetyl-amino-benzylaldehide and α-naftyl-amine. All synthesized compounds were characterized by elemental analysis, IR （infra red） spectroscopy and NMR （nuclear magnetic resonance） spectroscopy and evaluated for their in vitro antifungal activities of the compounds tested against Pseudomonas aeruginosa, Mycobacterium lacticolium, Aspergillus niger, Cladasporium resinale, Penicillium chrosegenum, Chastorniurn gloloodium and Trichoderma virideh. These derivatives have vast range of biological activities which benefit us.展开更多
Drinking water may be a risk factor for human infections if the water supply is contaminated with biofilm producing bacteria such as Legionella pneumophilae or Pseudomonas aeruginosa. Several situations have to be con...Drinking water may be a risk factor for human infections if the water supply is contaminated with biofilm producing bacteria such as Legionella pneumophilae or Pseudomonas aeruginosa. Several situations have to be considered when water supply to new buildings is planned. The aim of this paper is to review situations that have to be considered in new buildings and give an example on a new water supply contaminated with biofilm producing water bacteria and the precautions introduced to eliminate the contamination. When new buildings are planned it should be considered where to get the water and what is the microbiological quality of the water. If the water is contaminated there will be troubles from the beginning. The material for the pipes should be considered as biofilm which is produced in greater amounts and faster in PEG pipes than in stainless steel pipes. The choice of material depends on the expected lifetime of the building, the dimensions of the pipes, and the choice of forceps, how often the taps are used and thereby the flow in the system. The higher flow the less and slower biofilm formation. It is important to reduce the number of taps to a minimum to ovoid ＂dead ends＂ if they are not or only seldom used. Alternatively all taps could be opened automatically regularly. It is important to establish precautions to ovoid contamination of the water system in the period from when it is established until the building is taken in use. The period can be several months during which the system can act as a ＂dead end＂ if no precautions, such as regularly opening of all taps, are taken. The microbiological quality of the water in the system should be controlled before the building is taken in use. In a new building, where the water supply and the water in the building was not controlled before the building was taken in use, extremely high total and Legionella germ counts were found. The water was disinfected with low concentrations of chloride with very little effect. After disinfection with high concentrations of chloride for few hours and placing a sterile filter at the water entrance both the total and Legionella germ count decreased to an acceptable level.展开更多
基金supported by the National Natural Science Foundation of China(No.31301587)Key Laboratory of Aquatic Product Processing,Ministry of Agriculture,China
文摘Aquatic products are extremely perishable food commodities. Developing methods to keep the freshness of fish represents a major task of the fishery processing industry. Application of Lactic Acid Bacteria(LAB) as food preservative is a novel approach. In the present study, the possibility of using lactic acid bacteria in freshness keeping of tilapia fillets as sashimi was examined. Fish fillets were dipped in Lactobacillus plantarum 1.19(obtained from China General Microbiological Culture Collection Center) suspension as LAB-treated group. Changes in K-value, APC, sensory properties and microbial flora were analyzed. Results showed that LAB treatment slowed the increase of K-value and APC in the earlier storage, and caused a smooth decrease in sensory score. Gram-negative bacteria dominated during refrigerated storage, with Pseudomonas and Aeromonas being relatively abundant. Lactobacillus plantarum 1.19 had no obvious inhibitory effect against these Gram-negatives. However, Lactobacillus plantarum 1.19 changed the composition of Gram-positive bacteria. No Micrococcus were detected and the proportion of Staphylococcus decreased in the spoiled LAB-treated samples. The period that tilapia fillets could be used as sashimi material extended from 24 h to 48 h after LAB treatment. The potential of using LAB in sashimi processing was confirmed.
基金financial support from Zhang Zidao Sland Group Co.,Ltd. for the project (99801214)
文摘Bacterial community presumably plays an essential role in inhibiting pathogen colonization and maintaining the health of scallop larvae, but limiting data are available for Yesso scallop （Patinopecten yessoensisis Jay, 1857） larval development stages. The aim of this study was to characterize and compare the bacterial communities associating with Yesso scallop larval development at fertilized egg S l, trochophora S2, D-shaped larvae S3, umbo larvae S4, and juvenile scallop S5 stages by Illumina high-throughput sequencing. Genomic DNA was extracted from the larvae and their associating baetera, and a gene segment covering V3-V4 region of 16S rRNA gene was amplified and sequenced using an Illumina Miseq sequencer. Overall, 106760 qualified sequences with an average length of 449 bp were obtained. Sequences were compared with those retrieved from 16S rRNA gene databases, and 4 phyla, 7 classes, 15 orders, 21 families, 31 genera were identified. Proteobacteria was predominant phylum, accounting for more than 99%, at all 5 larval development stages. At genus level, Pseudomonas was dominant at stages S1 （80.60%）, S2 （87.77%） and S5 （68.71%）, followed by Photobacterium （17.06%） and Aeromonas （1.64%） at stage S1, Serratia （6.94%）, Stenotrophomonas （3.08%） and Acinetobacter （1.2%） at stage S2, Shewanella （25.95%） and Pseudoalteromonas （4.57%） at stage S5. Moreover, genus Pseudoal- teromonas became dominant at stages S3 （44.85%） and S4 （56.02%）, followed by Photobacterium （29.82%）, Pseudomonas （11.86%）, Aliivibrio （8.60%） and Shewanella （3.39%） at stage S3, Pseudomonas （18.16%）, Aliivibrio （14.29%）, Shewanella （4.11%）, Psychro- monas （4.04%） and Psychrobacter （1.81%） at stage S4. From the results, we concluded that the bacterial community changed sig- nificantly at different development stages of Yesso Scallop larvae.
基金Project (50621063) supported by the National Natural Science Foundation of ChinaProject (2004CB619204) supported by the Major State Basic Research and Development Program of China
文摘Strain E1 with resistance to 18 mmol/L cadmium （Cd）, isolated from Cd-contaminated soil was identified by morphological observation, biochemical and physiological characterization and 16S rDNA sequence analysis. The resistance to heavy metals Cd, Cu, Co, Mn, Pb, Zn and 12 antibiotics was examined. The ability of removing Cd from solution was studied. The characterizations show that strain El is affiliated to Pseudomonas aeruginosa （P aeruginosa）. Strain E1 has high resistance to heavy metals and the order is found to be Cd〉Mn〉Zn〉Cu〉Pb〉Co in solid media. Strain E1 also exhibits the resistance to 12 antibiotics. Both living and non-living cells of strain E1 can remove Cd from solution, and living cell has better biosorption than non-living cell.
文摘The present study identified the properties of porins in the outer membrane in Pseudomonas aeruginosa,and showed the role of outer membrane in determining imipenem diffusion in Pseudomonas aeruginosa The molecular weight of the major outer membrane protein was analyzed by SDS PAGE The purification of the porins in Pseudomonas aeruginosa was achieved by DEAE ion exchange HPLC The purified outer membrane proteins were reconstituted with phosphatidylcholine and dicetylphosphate into membrane vesicles, and were tested by the liposomes swelling method for the diffusion of imipenem The permeability assay showed that OprC (70 kD), OprD 2 (46kD), and OprE(43 kD) were the channel forming proteins But only OprD 2 was thought to be the likely route of imipenem diffusion
文摘Seaweeds are known to exhibit various antimicrobial properties, since it harbours an enormous range of indigenous bioactive compounds. The emergence of drug resistant strains has directed to the identification of prospective metabolites from seaweed and its endophytes, thereby exploiting the properties in resisting bacterial diseases. The current study was aimed to assess the antimicrobial activity of extracts obtained from Ulva reticulate, for which metabolites of Ulva reticulata and its endophytes were extracted and assessed against human pathogens like Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Bacillus subtilis. It was observed that the hexane extract of isolate VITDSJ2 was effective against all the tested pathogens but a significant inhibition was observed for Staphylococcus aureus and Escherichia coli. Further, Gas chromatography coupled with Mass spectroscopy （GC-MS） revealed the existence of phenol, 3, 5-bis （1, 1-dimethylethyl） in the crude hexane extract which is well-known to possess antibacterial activity. The effective isolate VITDSJ2 was identified to be the closest neighbour of Pseudomonas smtzeri by phenotypic and genotypic methods. The crude extracts of the seaweed Ulva reticulata was also screened for antibacterial activity and the hexane extract was effective in showing inhibition against all the tested pathogens. The compound in the crude extract of Ulva reticulata was identified as hentriacontane using GC-MS. The extracts obtained from dichloromethane did not show significant activity in comparison with the hexane extracts. Hence the metabolites of Ulva reticulata and the bacterial secondary metabolites of the endophytes could be used in the treatment of bacterial infections.
基金support provided by the National Natural Science Foundation of China (project No. 50975282)the Natural Science Foundation for Outstanding Youths, Chongqing, China (project No. CSTC,2008BA4037)
文摘A bacterial strain of the genus Pseudomonas aeruginosa was inoculated into a hydrocarbon culture medium and incubated for a definite period of time. The ability of the bacterial strain to biodegrade a hydrocarbon, viz. n-hexadecane, was evaluated through determining the hexadecane concentration in the inoculated culture medium on a gas chromatograph (GC). The effect of pH value on the degrading ability of the bacterial isolate and the impact of temperature on microbial growth were also explored. Test results showed that Pseudomonas aeruginosa was markedly effective in biodegrading n-hexadecane. Furthermore, the ability of Pseudomonas aeruginosa to biodegrade n-hexadecane was different at various pH values. Pseudomonas aeruginosa provided excellent degrading ability at a pH value of 7.0. The microbial cells of Pseudomonas aeruginosa increased with an increasing incubation duration at temperatures ranging from 28 ℃ to 35 ℃, and an exponential phase of microbial growth was observed.
文摘Bioflotation represents one of the growing trends to enhance the selectivity of conventional flotation processes. It utilizes the micro-organisms to replace or to interact with the chemical reagents to increase the gap between surface properties of similar minerals and to enhance the separation selectivity. In this work, dolomite-phosphate separation was investigated using amphoteric collector （dodecyl-N-carboxyethyl-N-hyroxyethyl-imidazoline） in presence of bacteria. Two types of bacteria, Corynebacterium- diphtheriae-intermedius （CDI）, and Pseudomonas aeruginosa （PA）, were used. The collector-bacteria interaction was characterized by Fourier transform infra-red （FTIR）, frothing height and Zeta potential. The results show that the collector-bacteria interaction improves the flotation selectivity. Although, the PA positively affects the separation results, the CDI cannot lower the MgO to less than 1%. A phosphate content of 0.7% MgO and 31.77% P205 with a recovery of 68% at pH 11, 3.0 kg/t amphoteric collector, 4× 10^7 cells of PA is obtained.
基金Project(108100) supported by the Key Program for Science and Technology Research of Ministry of Education of ChinaProjects(50978087, 50908081) supported by the National Natural Science Foundation of China+1 种基金Project(531107011019) supported by the Hunan University Graduate Education Innovation Program, ChinaProject(CX2010B157) supported by the Hunan Provincial Innovation Foundation for Postgraduate students, China
文摘Rhamnolipid production by Pseudomonas aeruginosa ATCC 9027 with waste frying oil as sole carbon source was studied using response surface method. Cultures were incubated in shaking flask with temperature, NO3- and Mg2+ concentrations as the variables. Meanwhile, fed-batch fermentation experiments were conducted. The results show that the three variables are closely related to rhamnolipid production. The optimal cultivation conditions are of 6.4 g/L NaNO3 , 3.1 g/L MgSO4 at 32 ℃, with the maximum rhamnolipid production of 6.6 g/L. The results of fed-batch fermentation experiments show that feeding the oil in two batches can enhance rhamnolipid production. The best time interval is 72 h with the maximum rhamnolipid production of 8.5 g/L. The data are potentially useful for mass production of rhamnolipid on oil waste with this bacterium.
文摘Algal blooms caused by eutrophication in fresh water are one of the major environmental problems in the world. Using biological methods to control algal growth, especially based on allelopathic inhibitory effects of aquatic macrophytes on phytoplankton growth, have been received world-wide attention. In this study, the allelopathic activity of the invasive macrophyte, Eichhornia crassipes （water hyacinth）, on blue-green algae, Microcystis aeruginosa （PCC7806） was investigated using coexistence assay. Our results showed that water hyacinth had disparate effects on the growth ofM~ aeruginosa （PCC7806） under different initial algal densities. Under lower initial algal density （OD650 = 0.10 and OD650 = 0.05）, the algal growth was significantly inhibited by water hyacinth （inhibition ratio was 95.6% and 97.3%, respectively）. While it was stimulated at higher initial algal densities （OD650 = 0.20）. Water hyacinth inhibited the growth of algae mainly through its root system. Culture water from water hyacinth and aqueous methanol extracts from dry roots samples also showed inhibition effects on algal growth. The inhibition effects increased as the increase of crude extract concentration, suggest that water hyacinth may excrete inhibitory substances from root system and show allelopathic inhibitory potential to the growth ofM. aeruginosa.
文摘One possible application for the excess of glycerol, which is an exceeding byproduct in biodiesel industry, was used as carbon and energy sources for bioproducts synthesis. This work aims to evaluate biosurfactant production from glycerol by Pseudomonas aeruginosa EQ 109 isolated from crude oil-contaminated soil. Factorial design 2^3 was utilized to optimize the amount of biosurfactant produced, by using pH （A）, initial biomass concentration （B）, and initial glycerol concentration （C） as independent factors. The experiments were carried out in flasks containing 100 mL of mineral medium. Biosurfactant production was monitored by increase of the emulsification of aviation kerosene （E24） and surface tension reduction （STr）. The results have shown that, at pH = 7.0, in order to increase E24, variables as B and C are the most influential, leading to a maximum value of E24 = 79%, as well as for an increase of GC （GCmax = 49%）. STR was the variable with the best correlation factor for the proposed linear model （R2=0.96） and its maximum value was 48%. Xfwas not significant to the model, although it was influenced by pH and C, with C = 40g/L （Xfmax = 4.56 g/L）.
文摘Ruta genus is a member of the family Rutaceae that has been cultivated widely in many regions of the world because of its medicinal properties. In Tessala Mountain （Sidi Bel Abbes Country, North-Western of Algeria）, the Ruta genus commonly known by ＂fidjel＂ is represented by two species： Ruta Chalepensis L. and Ruta Montana （L.） L. frequently used by local population in a traditional treatment. The water-distilled essential oils from this species yielded 7.23% and 6.104% for Ruta chalepensis L. and Ruta montana （L.） L. respectively. The essential oil of Ruta montana （L.） L. showed a strong antibacterial activity against all bacterial strains tested （Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Mycobacterium kansasii ATCC ! 2478 and Mycobacterium vaccae ATCC 1548314） compared to Ruta chalepensis L. oils which have a moderate effect only on Staphylococcus aureus ATCC 25923 and Pseudomonas aeruginosa ATCC 27853. Therefor, the antibacterial properties of the essential oils of Ruta Chalepensis L. and Ruta Montana （L.） L. are now well established through this study and therefore could justify their future uses in the treatment of nosocomial infections.
文摘Advanced material with antibacterial properties would be a promising way to improve the disinfection process in food plants. Our objective was to combine the bactericidal effect of TiO2 with the mechanical strength of TiN coatings. A TiO2 rutile film was obtained after annealing of a supplied 316 stainless steel with a TiN coating. This TiO2 upperlayer displays a photocatalytic activity under UV light exposure. The substrates with the TiN coating and the TiO2 upperlayer are more hydrophobic than the 316 control. The adhesion of either Listeria or Pseudomonas, on 316-TIN is characterized by the presence of clusters of cells, while the oxidation of the TiN surface leads to a more hydrophilic layer where cells are individualized. After UV illumination of the adherent cells and subsequent growth, the residual bacterial population present on 316-TIO2 is lower than that present on the 316-TIN. The bactericidal effect is more important on Listeria than on Pseudomonas.
文摘Biosurfactants were synthesized by Pseudomonas aeruginosa （P.A.）, using sugar cane molasses as carbon source. Assays were conducted in a shaker with agitation speed of 200 rpm, temperature of 38 ℃ and aeration ratio （Vm/Vf） of 0.4 and 0.6. A concentration of 3.0% was used for the carbon and energy source （molasses） and of 0.3% for the nitrogen source （NaNO3）. Samples were removed at regular times until 96 hours of cultivation. The reduction in surface tension was measured using the ring method; cell concentration was obtained by the dry mass and substrate consumption by the DNS method. The metabolite produced was extracted and quantified by the thioglycolic method. The results showed a maximum surface tension reduction of 46.57% after 60 h, 3.63 g/L of biomass after 8 h （μXmax =0.15 h^-1）, 79.60% of substrate consumption （μs= 0.67 h-1） and 4.47 g/L of rhamnolipid （μp=0.029 h^-1）.
文摘A new Shift bases was synthesized by the reaction of p-dimetyl-amino-benzylaldehide and α-naftyl-amine. All synthesized compounds were characterized by elemental analysis, IR （infra red） spectroscopy and NMR （nuclear magnetic resonance） spectroscopy and evaluated for their in vitro antifungal activities of the compounds tested against Pseudomonas aeruginosa, Mycobacterium lacticolium, Aspergillus niger, Cladasporium resinale, Penicillium chrosegenum, Chastorniurn gloloodium and Trichoderma virideh. These derivatives have vast range of biological activities which benefit us.
文摘Drinking water may be a risk factor for human infections if the water supply is contaminated with biofilm producing bacteria such as Legionella pneumophilae or Pseudomonas aeruginosa. Several situations have to be considered when water supply to new buildings is planned. The aim of this paper is to review situations that have to be considered in new buildings and give an example on a new water supply contaminated with biofilm producing water bacteria and the precautions introduced to eliminate the contamination. When new buildings are planned it should be considered where to get the water and what is the microbiological quality of the water. If the water is contaminated there will be troubles from the beginning. The material for the pipes should be considered as biofilm which is produced in greater amounts and faster in PEG pipes than in stainless steel pipes. The choice of material depends on the expected lifetime of the building, the dimensions of the pipes, and the choice of forceps, how often the taps are used and thereby the flow in the system. The higher flow the less and slower biofilm formation. It is important to reduce the number of taps to a minimum to ovoid ＂dead ends＂ if they are not or only seldom used. Alternatively all taps could be opened automatically regularly. It is important to establish precautions to ovoid contamination of the water system in the period from when it is established until the building is taken in use. The period can be several months during which the system can act as a ＂dead end＂ if no precautions, such as regularly opening of all taps, are taken. The microbiological quality of the water in the system should be controlled before the building is taken in use. In a new building, where the water supply and the water in the building was not controlled before the building was taken in use, extremely high total and Legionella germ counts were found. The water was disinfected with low concentrations of chloride with very little effect. After disinfection with high concentrations of chloride for few hours and placing a sterile filter at the water entrance both the total and Legionella germ count decreased to an acceptable level.
