Biofilm forming bacteria are omnipresent in the marine environment.Pseudoalteromonas is one of the largest within the γ-proteobacteria class,and a member of marine bacteria.Species of Pseudoalteromonas are generally ...Biofilm forming bacteria are omnipresent in the marine environment.Pseudoalteromonas is one of the largest within the γ-proteobacteria class,and a member of marine bacteria.Species of Pseudoalteromonas are generally found in association with marine eukaryotes.In this work,we present the isolation and characterization of two strains forming biofilm on rock surface and associated with marine sponge.They were identified using 16SrDNA as Pseudoalteromonas prydzensis alex,and Pseudoalteromonas sp.alex.They showed the highest titer in biofilm formation quantified using the test tube method using crystal violet.展开更多
Surfaces submerged in seawater are colonized by various microorganisms,resulting in the formation of heterogenic marine biofilms.This work aims to evaluate the biofilm formation by Cobetia marina alex and doing a comp...Surfaces submerged in seawater are colonized by various microorganisms,resulting in the formation of heterogenic marine biofilms.This work aims to evaluate the biofilm formation by Cobetia marina alex and doing a comparative study between this promising strain with the two bacterial strains isolated previously from the Mediterranean seawater,Alexandria,Egypt.Three strains;Cobetia marina alex,Pseudoalteromonas sp.alex,and Pseudoalteromonas prydzensis alex were screened for biofilm formation using the crystal violet(CV)quantification method in a single culture.The values of biofilm formed were OD600=3.0,2.7,and 2.6,respectively leading to their selection for further evaluation.However,factors affecting biofilm formation by C.marina alex were investigated.Biofilm formation was evaluated in single and multispecies consortia.Synergistic and antagonistic interactions proved in this work lead to the belief that these bacteria have the capability to produce some interesting signal molecules N-acyl Homoserine Lactones(AHLs).展开更多
Agar is an essential polysaccharide that has been utilized in numerous fields.Many kinds of literature have been published regarding agarolytic microorganisms’isolation and agarases biochemical studies.In this search...Agar is an essential polysaccharide that has been utilized in numerous fields.Many kinds of literature have been published regarding agarolytic microorganisms’isolation and agarases biochemical studies.In this search,a local marine agarolytic bacterium associated with marine alga Ulva lactuca surface was isolated and identified as Pseudoalteromonas sp.MHS.The agarase production was parallel to the growth of Pseudoalteromonas sp.MHS as cells displayed a lag phase(2 h),subsequently an exponential growth that prolonged till 10 h where maximum growth(OD550nm=3.9)was achieved.The enzyme activity increased rapidly as cells increased exponentially where the maximum activity of 0.22 U/mL was achieved after 8h and remained constant till 12 h during the stationary phase of growth.Agarase production was optimized using Plackett-Burman statistical design by measuring enzyme activity as a response and the design was validated using a verification experiment;the activity of the enzyme increased from 0.22 U/mL to 0.29 U/mL.Pseudoalteromonas sp.MHS agarase was partially purified and its molecular weight(MW)was determined by SDS-PAGE(15-25 kDa).Agarase showed approximately 94% of its activity at 40℃.The enzyme stability decreased as the temperature increased;the enzyme could retain about 98,90,80,75,and 60% of its activity at 20,30,40,50,and 60℃,respectively.Biomass of the red alga Pterocladia capillacea proved to be a suitable substrate for agarase production using Pseudoalteromonas sp.MHS;the enzyme activity recorded after 24 h of incubation was 0.35 U/mL compared to 0.29 U/mL from the optimized medium.展开更多
文摘Biofilm forming bacteria are omnipresent in the marine environment.Pseudoalteromonas is one of the largest within the γ-proteobacteria class,and a member of marine bacteria.Species of Pseudoalteromonas are generally found in association with marine eukaryotes.In this work,we present the isolation and characterization of two strains forming biofilm on rock surface and associated with marine sponge.They were identified using 16SrDNA as Pseudoalteromonas prydzensis alex,and Pseudoalteromonas sp.alex.They showed the highest titer in biofilm formation quantified using the test tube method using crystal violet.
文摘Surfaces submerged in seawater are colonized by various microorganisms,resulting in the formation of heterogenic marine biofilms.This work aims to evaluate the biofilm formation by Cobetia marina alex and doing a comparative study between this promising strain with the two bacterial strains isolated previously from the Mediterranean seawater,Alexandria,Egypt.Three strains;Cobetia marina alex,Pseudoalteromonas sp.alex,and Pseudoalteromonas prydzensis alex were screened for biofilm formation using the crystal violet(CV)quantification method in a single culture.The values of biofilm formed were OD600=3.0,2.7,and 2.6,respectively leading to their selection for further evaluation.However,factors affecting biofilm formation by C.marina alex were investigated.Biofilm formation was evaluated in single and multispecies consortia.Synergistic and antagonistic interactions proved in this work lead to the belief that these bacteria have the capability to produce some interesting signal molecules N-acyl Homoserine Lactones(AHLs).
文摘Agar is an essential polysaccharide that has been utilized in numerous fields.Many kinds of literature have been published regarding agarolytic microorganisms’isolation and agarases biochemical studies.In this search,a local marine agarolytic bacterium associated with marine alga Ulva lactuca surface was isolated and identified as Pseudoalteromonas sp.MHS.The agarase production was parallel to the growth of Pseudoalteromonas sp.MHS as cells displayed a lag phase(2 h),subsequently an exponential growth that prolonged till 10 h where maximum growth(OD550nm=3.9)was achieved.The enzyme activity increased rapidly as cells increased exponentially where the maximum activity of 0.22 U/mL was achieved after 8h and remained constant till 12 h during the stationary phase of growth.Agarase production was optimized using Plackett-Burman statistical design by measuring enzyme activity as a response and the design was validated using a verification experiment;the activity of the enzyme increased from 0.22 U/mL to 0.29 U/mL.Pseudoalteromonas sp.MHS agarase was partially purified and its molecular weight(MW)was determined by SDS-PAGE(15-25 kDa).Agarase showed approximately 94% of its activity at 40℃.The enzyme stability decreased as the temperature increased;the enzyme could retain about 98,90,80,75,and 60% of its activity at 20,30,40,50,and 60℃,respectively.Biomass of the red alga Pterocladia capillacea proved to be a suitable substrate for agarase production using Pseudoalteromonas sp.MHS;the enzyme activity recorded after 24 h of incubation was 0.35 U/mL compared to 0.29 U/mL from the optimized medium.
