Afifella marina strain ME (KC205142), a purple non-sulfur bacterium was isolated from mangrove habitats of Sabah. The effects of light intensities and photoperiods on proteolytic activity in Afifella marina strain ME ...Afifella marina strain ME (KC205142), a purple non-sulfur bacterium was isolated from mangrove habitats of Sabah. The effects of light intensities and photoperiods on proteolytic activity in Afifella marina strain ME (KC205142) were investigated. Secretion of proteolytic enzymes in Afifella marina was preliminarily assessed by skim milk agarose media. Subsequently, light intensities, such as, dark, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500 and 5000 lux were used to evaluate the effects on proteolytic activity in Afifella marina strain ME under anaerobic condition. After that, the effect of photoperiods on proteolytic activity was monitored under anaerobic light condition (3000 lux) at 0 h (0L/24D), 6 h (6L/18D), 12 h (12L/12D), 18 h (18L/6D) and 24 h (24L/0D) of photoperiod. The highest proteolytic activity of 74.67 U was recorded at 3000 lux illumination light intensity. The proteolytic activity in bacterium Afifella marina strain ME was positively associated with the dry cell weight. The proteolytic activity of 72.67 U in bacterium Afifella marina strain ME at 18 h (18L/6D) photoperiod is not significantly different (p > 0.05) from proteolytic activity of 74.67 U recorded at continuous light (24L/0D) condition. Light intensity of 3000 lux, culture period of 48 h and a photoperiod of 18 h (18L/ 6D) were the optimum parameters for proteolytic activity in bacterium Afifella marina strain ME.展开更多
Halorhodospira(Hlr.)halochloris is a triply extremophilic phototrophic purple sulfur bacterium,as it is thermophilic,alkaliphilic,and extremely halophilic.The light-harvesting-reaction center(LH1–RC)core complex of t...Halorhodospira(Hlr.)halochloris is a triply extremophilic phototrophic purple sulfur bacterium,as it is thermophilic,alkaliphilic,and extremely halophilic.The light-harvesting-reaction center(LH1–RC)core complex of this bacterium displays an LH1-Q_(y)transition at 1,016 nm,which is the lowest-energy wavelength absorption among all known phototrophs.Here we report the cryo-EM structure of the LH1–RC at 2.42?resolution.The LH1 complex forms a tricyclic ring structure composed of 16αβγ-polypeptides and oneαβ-heterodimer around the RC.From the cryo-EM density map,two previously unrecognized integral membrane proteins,referred to as protein G and protein Q,were identified.Both of these proteins are single transmembrane-spanning helices located between the LH1 ring and the RC Lsubunit and are absent from the LH1–RC complexes of all other purple bacteria of which the structures have been determined so far.Besides bacteriochlorophyll b molecules(B1020)located on the periplasmic side of the Hlr.halochloris membrane,there are also two arrays of bacteriochlorophyll b molecules(B800 and B820)located on the cytoplasmic side.Only a single copy of a carotenoid(lycopene)was resolved in the Hlr.halochloris LH1–α3β3 and this was positioned within the complex.The potential quinone channel should be the space between the LH1–α3β3 that accommodates the single lycopene but does not contain aγ-polypeptide,B800 and B820.Our results provide a structural explanation for the unusual Q_(y)red shift and carotenoid absorption in the Hlr.halochloris spectrum and reveal new insights into photosynthetic mechanisms employed by a species that thrives under the harshest conditions of any phototrophic microorganism known.展开更多
Soybean wastewater was used to generate biomass resource by use of purple non-sulfur bacteria（PNSB）. This study investigated the enhancement of PNSB cell accumulation in wastewater by Mg2＋under the light-anaerobic ...Soybean wastewater was used to generate biomass resource by use of purple non-sulfur bacteria（PNSB）. This study investigated the enhancement of PNSB cell accumulation in wastewater by Mg2＋under the light-anaerobic condition. Results showed that with the optimal Mg2＋dosage of 10 mg/L, biomass production was improved by 70% to 3630 mg/L,and biomass yield also was improved by 60%. Chemical Oxygen Demand（COD） removal reached above 86% and hydraulic retention time was shortened from 96 to 72 hr. The mechanism analysis indicated that Mg2＋could promote the content of bacteriochlorophyll in photosynthesis because Mg2＋is the bacteriochlorophyll active center, and thus improved adenosine triphosphate（ATP） production. An increase of ATP production enhanced the conversion of organic matter in wastewater into PNSB cell materials（biomass yield） and COD removal, leading to more biomass production. With 10 mg/L Mg2＋, bacteriochlorophyll content and ATP production were improved by 60% and 33% respectively.展开更多
文摘Afifella marina strain ME (KC205142), a purple non-sulfur bacterium was isolated from mangrove habitats of Sabah. The effects of light intensities and photoperiods on proteolytic activity in Afifella marina strain ME (KC205142) were investigated. Secretion of proteolytic enzymes in Afifella marina was preliminarily assessed by skim milk agarose media. Subsequently, light intensities, such as, dark, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500 and 5000 lux were used to evaluate the effects on proteolytic activity in Afifella marina strain ME under anaerobic condition. After that, the effect of photoperiods on proteolytic activity was monitored under anaerobic light condition (3000 lux) at 0 h (0L/24D), 6 h (6L/18D), 12 h (12L/12D), 18 h (18L/6D) and 24 h (24L/0D) of photoperiod. The highest proteolytic activity of 74.67 U was recorded at 3000 lux illumination light intensity. The proteolytic activity in bacterium Afifella marina strain ME was positively associated with the dry cell weight. The proteolytic activity of 72.67 U in bacterium Afifella marina strain ME at 18 h (18L/6D) photoperiod is not significantly different (p > 0.05) from proteolytic activity of 74.67 U recorded at continuous light (24L/0D) condition. Light intensity of 3000 lux, culture period of 48 h and a photoperiod of 18 h (18L/ 6D) were the optimum parameters for proteolytic activity in bacterium Afifella marina strain ME.
基金supported in part by the National Key R&D Program of China(No.2022YFC3401800)National Natural Science Foundation of China(32070264)+5 种基金Shandong Provincial Natural Science Foundation(ZR2019ZD48)the Strategic Priority Research Program of CAS(XDA26050402)the Science&Technology Specific Project in Agricultural High-tech Industrial Demonstration Area of the Yellow River Delta(2022SZX12)the Innovation Center for Academicians of Hainan Provincethe Specific Research Fund of the Innovation Center for Academicians of Hainan Province(No.YSPTZX202309)supported in part by NASA Cooperative Agreement 80NSSC21M0355。
文摘Halorhodospira(Hlr.)halochloris is a triply extremophilic phototrophic purple sulfur bacterium,as it is thermophilic,alkaliphilic,and extremely halophilic.The light-harvesting-reaction center(LH1–RC)core complex of this bacterium displays an LH1-Q_(y)transition at 1,016 nm,which is the lowest-energy wavelength absorption among all known phototrophs.Here we report the cryo-EM structure of the LH1–RC at 2.42?resolution.The LH1 complex forms a tricyclic ring structure composed of 16αβγ-polypeptides and oneαβ-heterodimer around the RC.From the cryo-EM density map,two previously unrecognized integral membrane proteins,referred to as protein G and protein Q,were identified.Both of these proteins are single transmembrane-spanning helices located between the LH1 ring and the RC Lsubunit and are absent from the LH1–RC complexes of all other purple bacteria of which the structures have been determined so far.Besides bacteriochlorophyll b molecules(B1020)located on the periplasmic side of the Hlr.halochloris membrane,there are also two arrays of bacteriochlorophyll b molecules(B800 and B820)located on the cytoplasmic side.Only a single copy of a carotenoid(lycopene)was resolved in the Hlr.halochloris LH1–α3β3 and this was positioned within the complex.The potential quinone channel should be the space between the LH1–α3β3 that accommodates the single lycopene but does not contain aγ-polypeptide,B800 and B820.Our results provide a structural explanation for the unusual Q_(y)red shift and carotenoid absorption in the Hlr.halochloris spectrum and reveal new insights into photosynthetic mechanisms employed by a species that thrives under the harshest conditions of any phototrophic microorganism known.
基金supported by the National Natural Science Foundation of China(No.51278489)
文摘Soybean wastewater was used to generate biomass resource by use of purple non-sulfur bacteria（PNSB）. This study investigated the enhancement of PNSB cell accumulation in wastewater by Mg2＋under the light-anaerobic condition. Results showed that with the optimal Mg2＋dosage of 10 mg/L, biomass production was improved by 70% to 3630 mg/L,and biomass yield also was improved by 60%. Chemical Oxygen Demand（COD） removal reached above 86% and hydraulic retention time was shortened from 96 to 72 hr. The mechanism analysis indicated that Mg2＋could promote the content of bacteriochlorophyll in photosynthesis because Mg2＋is the bacteriochlorophyll active center, and thus improved adenosine triphosphate（ATP） production. An increase of ATP production enhanced the conversion of organic matter in wastewater into PNSB cell materials（biomass yield） and COD removal, leading to more biomass production. With 10 mg/L Mg2＋, bacteriochlorophyll content and ATP production were improved by 60% and 33% respectively.
