Objective Bioremediation technology has gained importance because microbes could be the convenient source of bio-absorption/bioaccumulation of metals from effluent streams. Methods The nickel-resistant bacterial isola...Objective Bioremediation technology has gained importance because microbes could be the convenient source of bio-absorption/bioaccumulation of metals from effluent streams. Methods The nickel-resistant bacterial isolates （NiRBI） were selected from various bacterial isolates from industrial effluent and grown in nutrient broth containing different concentrations of nickel sulfate （0.3-3.0 mmol/L） and their capability of accumulating metal from the medium. Results Well-defined growth of NiRBI was observed in the medium containing up to 2.5 mmol/L of nickel. The isolate was identified using 16S rRNA and closely related to Pseudomonas fragi. Maximum accumulation of nickel （0.59 mg/g dry weight of bacterial cells） was observed when NiRBI was grown in media containing 2 mmol/L of nickel. The protein profile of the NiRBI cellular extract by SDS-PAGE showed two metal stress-induced proteins of molecular weight 48 KD and 18 KD with a simultaneous down regulation of four proteins of 46.7 KD, 42.2 KD, 19.7 KD, and 4.0 KD. Conclusion 48 KD and 18 KD proteins play a role in metal resistance mechanism by NiRBI.展开更多
AIM: Anaerobic bacteria can cause ocular infections. We tested the OxyPlateTM Anaerobic System (OXY) to isolate pertinent anaerobic bacteria that can cause ocular disease.METHODS: OXY, which does not require direct an...AIM: Anaerobic bacteria can cause ocular infections. We tested the OxyPlateTM Anaerobic System (OXY) to isolate pertinent anaerobic bacteria that can cause ocular disease.METHODS: OXY, which does not require direct anaerobic conditions (i.e. bags, jars), was compared to conventional isolation of incubating culture media in anaerobic bags. Standard colonies counts were performed on anaerobic ocular bacterial isolates under aerobic and anaerobic conditions (anaerobic bags) using agar media: 1) OXY (aerobic only), 2) 5% sheep blood (SB), 3) Chocolate, and 4) Schaedler. The bacteria tested were de-identified ocular isolates cultured from endophthalmitis and dacryocystitis that include 10 Propionibacterium acnes and 3 Actinomyces species. The colony counts for each bacteria isolate, on each culturing condition, were ranked from largest to smallest, and non-parametrically compared to determine the best culturing condition.RESULTS: All anaerobic conditions were positive for all of the anaerobic isolates. SB and Schaedler’s agar under aerobic conditions did not support the growth of anaerobic bacteria. Sparse growth was noted on chocolate agar with Propionibacterium acnes . As an anaerobic system, SB in an anaerobic bag isolated higher colony counts than OXY (P=0.0028) and chocolate agar (P=0.0028).CONCLUSION: Although OXY did not test to be more efficient than other anaerobic systems, it appears to be a reasonable alternative for isolating anaerobic bacteria from ocular sites. The use of an agar medium in a specially designed plate, without the requirement of an anaerobic bag, rendered OXY as an advantage over other anaerobic systems.展开更多
Hospital laboratory wastewater has been considered to significantly change the degree of contamination of especially the hospital wastewater. The present study investigated the hospital clinical laboratory wastewater ...Hospital laboratory wastewater has been considered to significantly change the degree of contamination of especially the hospital wastewater. The present study investigated the hospital clinical laboratory wastewater and the pollution loads were assessed for pathogens, heavy metals, and organic materials. Composite samples were collected from clinical laboratory wastewater of a 350-bed hospital for a six-month period. Analyses for pH, TSS (Total Suspended Solid), BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), PO4-P, and Cl as well as heavy metals (Cd, Pb, Zn, Cu, Cr, Co, Ni, Al, and Mn) were made in order to physiochemical properties of the samples. Bacterial isolation (Pseudomonas aeruginosa, Escherichia coli, Acinetobaumanii, CNS—Coagulase- Negative Staphylococcus) and antigen-antibody analyses were conducted in order to find the microbiological pollution load of the wastewater. As a result of the study it was found that the hospital clinical laboratory wastewater was alkaline and COD/BOD ratio reached to a range of 10 - 12 in the wastewater. It was concluded that although the heavy metal concentrations were within the sewage discharge limits the said levels could pose health risk. It was also found that the wastewater entailed health risk due to pathogens.展开更多
Black soldier fly(BSF),Hermetia illucens(Diptera:Stratiomyidae),is a promi-nent insect for the bioconversion of various organic wastes.As a saprotrophic insect,the BSF inhabits microbe-rich environments.However,the in...Black soldier fly(BSF),Hermetia illucens(Diptera:Stratiomyidae),is a promi-nent insect for the bioconversion of various organic wastes.As a saprotrophic insect,the BSF inhabits microbe-rich environments.However,the influences of the intestinal mi-croorganisms on BSF growth and development are not very clear.In this study,the dy-namics of the intestinal bacterial community of BSF larvae(BSFL)were analyzed using pyrosequencing.Actinobacteria,Bacteroidetes,Firmicutes,and Proteobacteria were the most prevalent bacterial phyla in the intestines of all larval instars.The dynamic changes in bacterial community compositions among different larval instars were striking at the genus level.Klebsiella,Clostridium,Providencia,and Dysgonomonas were the relatively most abundant bacteria in the 1st-to 4th-instar BSFL,respectively.Dysgonomonas and Providencia also dominated the 5th-and 6th-instar larvae,at ratios of 31.1%and 47.2%,respectively.In total,148 bacterial strains affiliated with 20 genera were isolated on differ-ent media under aerobic and anaerobic conditions.Among them,6 bacteria,BSF1-BSF6,were selected for further study.The inoculation of the 6 isolates independently into germ-free BSFL feeding on an artificial diet showed that all the bacteria,except BSF4,sig-nificantly promoted BSF growth and development compared with the germ-free control.Citrobacter,Dysgonomonas,Klebsiella,Ochrobactrum,and Providencia promoted BSF development significantly by increasing the weight gains of larvae and pupae,as well as increasing the prepupae and eclosion rates.In addition,Citrobacter,Klebsiella and Prov-idencia shortened the BSF life cycle significantly.The results illustrate the promotive effects of intestinal bacteria on BSF growth and development.展开更多
Urinary tract infections (UTIs) are one of the most prevalent extra-intestinal bacterial infections. It is a common disease encountered in medical practice affecting people of all ages, from neonate to geriatric age g...Urinary tract infections (UTIs) are one of the most prevalent extra-intestinal bacterial infections. It is a common disease encountered in medical practice affecting people of all ages, from neonate to geriatric age group. These infections are on the increase for outpatients attending Primary Health Centres in Anambra State, Nigeria, therefore the need for this study. The prevalence rate of urinary tract infection, age distribution and influence of sex were determined. Susceptibility pattern of the infectious organisms to antimicrobial agent were examined. Clean-catch midstream urine samples were collected and examined. Out of 3000 urine samples examined, 528 bacterial isolates were recovered and characterized. These include: Escherichia coli (24.2%), Klebsiella spp. (18.2%), Staphylococcus aureus (18.2%), Proteus mirabilis (9.1%), Pseudomonas aeruginosa (9.1%), Enterococcus faecalis (9.1%), Citrobacter intermedius (6.1%) and Staphylococcus saprophyticus (6.1%). More females (52%) were infected than males (48%) and in both sexes, the highest incidence was found amongst the age group, 26 - 38 years. Gram negative rods had the highest incidence in both sexes. Among the towns in Anambra state, Umunya in southern province was observed to have the highest incidence rate of UTI. Susceptibility test of the bacterial isolates to antimicrobial agents showed that Staphylococcus aureus was sensitive to Cephalexin, Penicillin V, Erythromycin and Gentamycin while Pseudomonas aeruginosa was resistant to all the antibiotics. Escherichia coli and Klebsiella spp. were resistant to all the antibiotics except Gentamycin while Citrobacter intermedius was resistant only to Cephalexin and Erythromycin. This study provides the evidence of urinary tract infections amongst outpatients of primary health centres and the drugs for their control.展开更多
Aerobic granule is a special microbial aggregate associated with biofilm structure.The formation of aerobic granular sludge is primarily depending on its bacterial community and relevant microbiological properties.In ...Aerobic granule is a special microbial aggregate associated with biofilm structure.The formation of aerobic granular sludge is primarily depending on its bacterial community and relevant microbiological properties.In this experiment,a strain with high microbial attachment was isolated from aerobic granular sludge,and the detailed characteristics were examined.Its high attachment ability could reach 2.34(OD600 nm),while other low attachment values were only around 0.06-0.32,which indicated a big variation among the different bacteria.The strain exhibited a very special morphology with many fibric fingers under SEM observation.A distinctive behaviour was to form a spherical particle by themselves,which would be very beneficial for the formation and development of granular sludge.The EPS measurement showed that its PN content was higher than low attachment bacteria,and 3 DEEM confirmed that there were some different components.Based on the 16 S rRNA analysis,it was identified to mostly belong to Stenotrophomonas.Its augmentation to particle sludge cultivation demonstrated that the strain could significantly promote the formation of aerobic granule.Conclusively,it was strongly suggested that it might be used as a good and potential model strain or chassis organism for the aerobic granular sludge formation and development.展开更多
Ninety-four percent of 336 strains Klebsiellapneumoniae were resistant to ampicillin，while less than 10％were resistant to cefotaxine and ceftazidine.Among all theaminoglycosides tested,amikacin had the strongest act...Ninety-four percent of 336 strains Klebsiellapneumoniae were resistant to ampicillin，while less than 10％were resistant to cefotaxine and ceftazidine.Among all theaminoglycosides tested,amikacin had the strongest activity on K.展开更多
The sulfur-containing odor emitted from sludge composting could be controlled by sulfide oxidizing bacteria, yet mesophilic strains show inactivation during the thermophilic stage of composting. Aimed to investigate a...The sulfur-containing odor emitted from sludge composting could be controlled by sulfide oxidizing bacteria, yet mesophilic strains show inactivation during the thermophilic stage of composting. Aimed to investigate and characterize the thermotolerant bacterium that could oxidize sulfide into sulfate, a heterotrophic strain was isolated from sewage sludge composting and identified as Paenibacillus naphthalenovorans LYH-3. The effects of various environmental factors on sulfide oxidation capacities were studied to optimize the sulfate production, and the highest production rate (27.35%±0.86%) was obtained at pH 7.34, the rotation speed of 161.14 r/min, and the inoculation amount of 5.83%by employing BoxBehnken design. The results of serial sulfide substrates experiments indicated that strain LYH-3 could survive up to 400 mg/L of sulfide with the highest sulfide removal rate (88.79%±0.35%) obtained at 50 mg/L of sulfide. Growth kinetic analysis presented the maximum specific growth rateμm(0.5274 hr-1) after 22 hr cultivation at 50℃. The highest enzyme activities of sulfide quinone oxidoreductase (0.369±0.052 U/mg) and sulfur dioxygenase (0.255±0.014 U/mg) were both obtained at 40℃, and the highest enzyme activity of sulfite acceptor oxidoreductase (1.302±0.035 U/mg) was assessed at 50℃. The results indicated that P. naphthalenovorans possessed a rapid growth rate and efficient sulfide oxidation capacities under thermophilic conditions, promising a potential application in controlling sulfur-containing odors during the thermophilic stage of sludge composting.展开更多
A newly isolated bacterium, named as AUH-JLC257, was found to be capable of bioconverting isoflavone genistein to 5-hydroxy-equol under anaerobic conditions. The metabolite 5-hydroxy-equol was identified by using UV s...A newly isolated bacterium, named as AUH-JLC257, was found to be capable of bioconverting isoflavone genistein to 5-hydroxy-equol under anaerobic conditions. The metabolite 5-hydroxy-equol was identified by using UV spectrum, electrospray ionization mass spectrometry （ESI-MS） as well as IH and 13C NMR analyses. Chiral stationary-phase high-performance liquid chromatography analysis and specific rotation examination demonstrated that the bio-synthesized 5-hydroxy-equol was just （-）-5-hydroxy-equol. The average bioconverting rate was 83.1%, and the strain AUH-JLC257 could efficiently transform genistein at a maximal substrate concentration of 0.6 mmol/L. We, for the first time, showed that the bio-synthesized 5-hydroxy-equol had 1,1-diphenyl-2-picrylhydrazyl （DPPH） radical-scavenging activity at concentrations as low as 3.3μmol/L. In addition, the 16S rRNA gene sequence （1401 bp） of the bacterium strain AUH-JLC257 showed the highest similarity （99.27%） to that of Slackia equolifaciens strain DZE.展开更多
The soluble microbial products （SMP） in the biological treatment effluent are generally of great amount and are poorly biodegradable. Focusing on the biodegradation of anaerobic SMP, the biological activated carbon ...The soluble microbial products （SMP） in the biological treatment effluent are generally of great amount and are poorly biodegradable. Focusing on the biodegradation of anaerobic SMP, the biological activated carbon （BAC） was introduced into the anaerobic system. The experiments were conducted in two identical lab-scale up-flow anaerobic sludge blanket （UASB） reactors. The high strength organics were degraded in the first UASB reactor （UASB1） and the second UASB （UASB2, i.e., BAC） functioned as a polishing step to remove SMP produced in UASB1. The results showed that 90% of the SMP could be removed before granular activated carbon was saturated. After the saturation, the SMP removal decreased to 60% on the average. Analysis of granular activated carbon adsorption revealed that the main role of SMP removal in BAC reactor was biodegradation. A strain of SMP-degrading bacteria, which was found highly similar to Klebsiella sp., was isolated, enriched and inoculated back to the BAC reactor. When the influent chemical oxygen demand （COD） was 10,000 mg/L and the organic loading rate achieved 10 kg COD/（m 3 ·day）, the effluent from the BAC reactor could meet the discharge standard without further treatment. Anaerobic BAC reactor inoculated with the isolated Klebsiella was proved to be an effective, cheap and easy technical treatment approach for the removal of SMP in the treatment of easily-degradable wastewater with COD lower than 10,000 mg/L.展开更多
The present study focuses on the isolation of bacterial pathogens from waste disposal sites,and examination of their efficiencies for degrading various plastics.Seven bacterial isolates such as E.coli,Corynebacterium ...The present study focuses on the isolation of bacterial pathogens from waste disposal sites,and examination of their efficiencies for degrading various plastics.Seven bacterial isolates such as E.coli,Corynebacterium spp.,Micrococcus spp.,Azotobacter spp.,Pseudomonas spp.,Staphylococcus spp.,and Bacillus spp.were identified.Bacillus spp.exhibited the highest percentage reduction in black plastic weight(47.46%),while Corynebacterium spp.,and E.coli achieved a maximum reduction of 45.76 and 46.42%for pink plastic respectively.Pseudomonas spp.and Micrococcus spp.demonstrated notable reductions of 46.43%and 56.60%in white and Canteen Stores Department(CSD)biodegradable plastics,respectively.Optical density(OD)measurements revealed that bacterial isolates achieved maximum OD values with CSD plastics,emphasizing their proficiency in plastic degradation.Fourier Transform Infrared Spectroscopy(FTIR)confirmed the degradation process,with a decrease in the peak value from 2916 to 2914 cm^(-1) for pink plastic,signifying alkane,and alkene presence.Three new peaks at 1398,1371,and 1361 cm^(-1) in the FTIR spectrum of CSD plastic indicated presence of alcohol.Scanning Electron Microscopic(SEM)micrographs illustrated bacterial colonization,cracks,and spots on plastic surfaces,while Xray Diffraction(XRD)spectra showed peaks at 4.083,3.705,3.020,and 1.909,suggesting plastic degradation.In conclusion,soil of waste disposal site harbored diverse microbial species,and have highlighted their effectiveness in mitigating environmental pollution by degrading hazardous plastic waste.展开更多
文摘Objective Bioremediation technology has gained importance because microbes could be the convenient source of bio-absorption/bioaccumulation of metals from effluent streams. Methods The nickel-resistant bacterial isolates （NiRBI） were selected from various bacterial isolates from industrial effluent and grown in nutrient broth containing different concentrations of nickel sulfate （0.3-3.0 mmol/L） and their capability of accumulating metal from the medium. Results Well-defined growth of NiRBI was observed in the medium containing up to 2.5 mmol/L of nickel. The isolate was identified using 16S rRNA and closely related to Pseudomonas fragi. Maximum accumulation of nickel （0.59 mg/g dry weight of bacterial cells） was observed when NiRBI was grown in media containing 2 mmol/L of nickel. The protein profile of the NiRBI cellular extract by SDS-PAGE showed two metal stress-induced proteins of molecular weight 48 KD and 18 KD with a simultaneous down regulation of four proteins of 46.7 KD, 42.2 KD, 19.7 KD, and 4.0 KD. Conclusion 48 KD and 18 KD proteins play a role in metal resistance mechanism by NiRBI.
基金Supported in part by The Charles T.Campbell Foundation: The Pennsylvania Lions ClubNational Institutes of Health grant P30EY008098 (Bethesda,MD)+1 种基金Eye and Ear Foundation (Pittsburgh, PA)unrestricted grants from Research to Prevent Blindness(New York, NY)
文摘AIM: Anaerobic bacteria can cause ocular infections. We tested the OxyPlateTM Anaerobic System (OXY) to isolate pertinent anaerobic bacteria that can cause ocular disease.METHODS: OXY, which does not require direct anaerobic conditions (i.e. bags, jars), was compared to conventional isolation of incubating culture media in anaerobic bags. Standard colonies counts were performed on anaerobic ocular bacterial isolates under aerobic and anaerobic conditions (anaerobic bags) using agar media: 1) OXY (aerobic only), 2) 5% sheep blood (SB), 3) Chocolate, and 4) Schaedler. The bacteria tested were de-identified ocular isolates cultured from endophthalmitis and dacryocystitis that include 10 Propionibacterium acnes and 3 Actinomyces species. The colony counts for each bacteria isolate, on each culturing condition, were ranked from largest to smallest, and non-parametrically compared to determine the best culturing condition.RESULTS: All anaerobic conditions were positive for all of the anaerobic isolates. SB and Schaedler’s agar under aerobic conditions did not support the growth of anaerobic bacteria. Sparse growth was noted on chocolate agar with Propionibacterium acnes . As an anaerobic system, SB in an anaerobic bag isolated higher colony counts than OXY (P=0.0028) and chocolate agar (P=0.0028).CONCLUSION: Although OXY did not test to be more efficient than other anaerobic systems, it appears to be a reasonable alternative for isolating anaerobic bacteria from ocular sites. The use of an agar medium in a specially designed plate, without the requirement of an anaerobic bag, rendered OXY as an advantage over other anaerobic systems.
文摘Hospital laboratory wastewater has been considered to significantly change the degree of contamination of especially the hospital wastewater. The present study investigated the hospital clinical laboratory wastewater and the pollution loads were assessed for pathogens, heavy metals, and organic materials. Composite samples were collected from clinical laboratory wastewater of a 350-bed hospital for a six-month period. Analyses for pH, TSS (Total Suspended Solid), BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), PO4-P, and Cl as well as heavy metals (Cd, Pb, Zn, Cu, Cr, Co, Ni, Al, and Mn) were made in order to physiochemical properties of the samples. Bacterial isolation (Pseudomonas aeruginosa, Escherichia coli, Acinetobaumanii, CNS—Coagulase- Negative Staphylococcus) and antigen-antibody analyses were conducted in order to find the microbiological pollution load of the wastewater. As a result of the study it was found that the hospital clinical laboratory wastewater was alkaline and COD/BOD ratio reached to a range of 10 - 12 in the wastewater. It was concluded that although the heavy metal concentrations were within the sewage discharge limits the said levels could pose health risk. It was also found that the wastewater entailed health risk due to pathogens.
基金supported by the National Natural Science Foundation of China(31670004)the Fundamental Research Funds for the Central Universities,Central China Normal University(KJ02072019-0383 and CCNU20CG005).
文摘Black soldier fly(BSF),Hermetia illucens(Diptera:Stratiomyidae),is a promi-nent insect for the bioconversion of various organic wastes.As a saprotrophic insect,the BSF inhabits microbe-rich environments.However,the influences of the intestinal mi-croorganisms on BSF growth and development are not very clear.In this study,the dy-namics of the intestinal bacterial community of BSF larvae(BSFL)were analyzed using pyrosequencing.Actinobacteria,Bacteroidetes,Firmicutes,and Proteobacteria were the most prevalent bacterial phyla in the intestines of all larval instars.The dynamic changes in bacterial community compositions among different larval instars were striking at the genus level.Klebsiella,Clostridium,Providencia,and Dysgonomonas were the relatively most abundant bacteria in the 1st-to 4th-instar BSFL,respectively.Dysgonomonas and Providencia also dominated the 5th-and 6th-instar larvae,at ratios of 31.1%and 47.2%,respectively.In total,148 bacterial strains affiliated with 20 genera were isolated on differ-ent media under aerobic and anaerobic conditions.Among them,6 bacteria,BSF1-BSF6,were selected for further study.The inoculation of the 6 isolates independently into germ-free BSFL feeding on an artificial diet showed that all the bacteria,except BSF4,sig-nificantly promoted BSF growth and development compared with the germ-free control.Citrobacter,Dysgonomonas,Klebsiella,Ochrobactrum,and Providencia promoted BSF development significantly by increasing the weight gains of larvae and pupae,as well as increasing the prepupae and eclosion rates.In addition,Citrobacter,Klebsiella and Prov-idencia shortened the BSF life cycle significantly.The results illustrate the promotive effects of intestinal bacteria on BSF growth and development.
文摘Urinary tract infections (UTIs) are one of the most prevalent extra-intestinal bacterial infections. It is a common disease encountered in medical practice affecting people of all ages, from neonate to geriatric age group. These infections are on the increase for outpatients attending Primary Health Centres in Anambra State, Nigeria, therefore the need for this study. The prevalence rate of urinary tract infection, age distribution and influence of sex were determined. Susceptibility pattern of the infectious organisms to antimicrobial agent were examined. Clean-catch midstream urine samples were collected and examined. Out of 3000 urine samples examined, 528 bacterial isolates were recovered and characterized. These include: Escherichia coli (24.2%), Klebsiella spp. (18.2%), Staphylococcus aureus (18.2%), Proteus mirabilis (9.1%), Pseudomonas aeruginosa (9.1%), Enterococcus faecalis (9.1%), Citrobacter intermedius (6.1%) and Staphylococcus saprophyticus (6.1%). More females (52%) were infected than males (48%) and in both sexes, the highest incidence was found amongst the age group, 26 - 38 years. Gram negative rods had the highest incidence in both sexes. Among the towns in Anambra state, Umunya in southern province was observed to have the highest incidence rate of UTI. Susceptibility test of the bacterial isolates to antimicrobial agents showed that Staphylococcus aureus was sensitive to Cephalexin, Penicillin V, Erythromycin and Gentamycin while Pseudomonas aeruginosa was resistant to all the antibiotics. Escherichia coli and Klebsiella spp. were resistant to all the antibiotics except Gentamycin while Citrobacter intermedius was resistant only to Cephalexin and Erythromycin. This study provides the evidence of urinary tract infections amongst outpatients of primary health centres and the drugs for their control.
基金supported by the National Natural Science Foundation of China(No.51578069)Beijing Science and Technology Commission Project(No.Z171100000717012)。
文摘Aerobic granule is a special microbial aggregate associated with biofilm structure.The formation of aerobic granular sludge is primarily depending on its bacterial community and relevant microbiological properties.In this experiment,a strain with high microbial attachment was isolated from aerobic granular sludge,and the detailed characteristics were examined.Its high attachment ability could reach 2.34(OD600 nm),while other low attachment values were only around 0.06-0.32,which indicated a big variation among the different bacteria.The strain exhibited a very special morphology with many fibric fingers under SEM observation.A distinctive behaviour was to form a spherical particle by themselves,which would be very beneficial for the formation and development of granular sludge.The EPS measurement showed that its PN content was higher than low attachment bacteria,and 3 DEEM confirmed that there were some different components.Based on the 16 S rRNA analysis,it was identified to mostly belong to Stenotrophomonas.Its augmentation to particle sludge cultivation demonstrated that the strain could significantly promote the formation of aerobic granule.Conclusively,it was strongly suggested that it might be used as a good and potential model strain or chassis organism for the aerobic granular sludge formation and development.
文摘Ninety-four percent of 336 strains Klebsiellapneumoniae were resistant to ampicillin，while less than 10％were resistant to cefotaxine and ceftazidine.Among all theaminoglycosides tested,amikacin had the strongest activity on K.
基金supported by the National Natural Science Foundation of China(No. 51878216)。
文摘The sulfur-containing odor emitted from sludge composting could be controlled by sulfide oxidizing bacteria, yet mesophilic strains show inactivation during the thermophilic stage of composting. Aimed to investigate and characterize the thermotolerant bacterium that could oxidize sulfide into sulfate, a heterotrophic strain was isolated from sewage sludge composting and identified as Paenibacillus naphthalenovorans LYH-3. The effects of various environmental factors on sulfide oxidation capacities were studied to optimize the sulfate production, and the highest production rate (27.35%±0.86%) was obtained at pH 7.34, the rotation speed of 161.14 r/min, and the inoculation amount of 5.83%by employing BoxBehnken design. The results of serial sulfide substrates experiments indicated that strain LYH-3 could survive up to 400 mg/L of sulfide with the highest sulfide removal rate (88.79%±0.35%) obtained at 50 mg/L of sulfide. Growth kinetic analysis presented the maximum specific growth rateμm(0.5274 hr-1) after 22 hr cultivation at 50℃. The highest enzyme activities of sulfide quinone oxidoreductase (0.369±0.052 U/mg) and sulfur dioxygenase (0.255±0.014 U/mg) were both obtained at 40℃, and the highest enzyme activity of sulfite acceptor oxidoreductase (1.302±0.035 U/mg) was assessed at 50℃. The results indicated that P. naphthalenovorans possessed a rapid growth rate and efficient sulfide oxidation capacities under thermophilic conditions, promising a potential application in controlling sulfur-containing odors during the thermophilic stage of sludge composting.
基金National Natural Science Foundation of China(Grant No.31170058)the Service Center for Experts and Scholars of Hebei Province(Grant No.CPRC027)
文摘A newly isolated bacterium, named as AUH-JLC257, was found to be capable of bioconverting isoflavone genistein to 5-hydroxy-equol under anaerobic conditions. The metabolite 5-hydroxy-equol was identified by using UV spectrum, electrospray ionization mass spectrometry （ESI-MS） as well as IH and 13C NMR analyses. Chiral stationary-phase high-performance liquid chromatography analysis and specific rotation examination demonstrated that the bio-synthesized 5-hydroxy-equol was just （-）-5-hydroxy-equol. The average bioconverting rate was 83.1%, and the strain AUH-JLC257 could efficiently transform genistein at a maximal substrate concentration of 0.6 mmol/L. We, for the first time, showed that the bio-synthesized 5-hydroxy-equol had 1,1-diphenyl-2-picrylhydrazyl （DPPH） radical-scavenging activity at concentrations as low as 3.3μmol/L. In addition, the 16S rRNA gene sequence （1401 bp） of the bacterium strain AUH-JLC257 showed the highest similarity （99.27%） to that of Slackia equolifaciens strain DZE.
基金supported by the National Natural Science Foundation of China (No. 50808121)the Program for New Century Excellent Talents in University (No. NCET-11-0320)
文摘The soluble microbial products （SMP） in the biological treatment effluent are generally of great amount and are poorly biodegradable. Focusing on the biodegradation of anaerobic SMP, the biological activated carbon （BAC） was introduced into the anaerobic system. The experiments were conducted in two identical lab-scale up-flow anaerobic sludge blanket （UASB） reactors. The high strength organics were degraded in the first UASB reactor （UASB1） and the second UASB （UASB2, i.e., BAC） functioned as a polishing step to remove SMP produced in UASB1. The results showed that 90% of the SMP could be removed before granular activated carbon was saturated. After the saturation, the SMP removal decreased to 60% on the average. Analysis of granular activated carbon adsorption revealed that the main role of SMP removal in BAC reactor was biodegradation. A strain of SMP-degrading bacteria, which was found highly similar to Klebsiella sp., was isolated, enriched and inoculated back to the BAC reactor. When the influent chemical oxygen demand （COD） was 10,000 mg/L and the organic loading rate achieved 10 kg COD/（m 3 ·day）, the effluent from the BAC reactor could meet the discharge standard without further treatment. Anaerobic BAC reactor inoculated with the isolated Klebsiella was proved to be an effective, cheap and easy technical treatment approach for the removal of SMP in the treatment of easily-degradable wastewater with COD lower than 10,000 mg/L.
基金Deanship of Scientific Research,Qassim University for funding the publication of this project.
文摘The present study focuses on the isolation of bacterial pathogens from waste disposal sites,and examination of their efficiencies for degrading various plastics.Seven bacterial isolates such as E.coli,Corynebacterium spp.,Micrococcus spp.,Azotobacter spp.,Pseudomonas spp.,Staphylococcus spp.,and Bacillus spp.were identified.Bacillus spp.exhibited the highest percentage reduction in black plastic weight(47.46%),while Corynebacterium spp.,and E.coli achieved a maximum reduction of 45.76 and 46.42%for pink plastic respectively.Pseudomonas spp.and Micrococcus spp.demonstrated notable reductions of 46.43%and 56.60%in white and Canteen Stores Department(CSD)biodegradable plastics,respectively.Optical density(OD)measurements revealed that bacterial isolates achieved maximum OD values with CSD plastics,emphasizing their proficiency in plastic degradation.Fourier Transform Infrared Spectroscopy(FTIR)confirmed the degradation process,with a decrease in the peak value from 2916 to 2914 cm^(-1) for pink plastic,signifying alkane,and alkene presence.Three new peaks at 1398,1371,and 1361 cm^(-1) in the FTIR spectrum of CSD plastic indicated presence of alcohol.Scanning Electron Microscopic(SEM)micrographs illustrated bacterial colonization,cracks,and spots on plastic surfaces,while Xray Diffraction(XRD)spectra showed peaks at 4.083,3.705,3.020,and 1.909,suggesting plastic degradation.In conclusion,soil of waste disposal site harbored diverse microbial species,and have highlighted their effectiveness in mitigating environmental pollution by degrading hazardous plastic waste.
