Rhodopseudomonas palustris, one of purple nonsulfur photosynthetic bacteria, fixes carbon dioxide via Calvin-Benson cycle and has been shown previously to express form I and form II ribulose-1,5-bisphosphate carboxyla...Rhodopseudomonas palustris, one of purple nonsulfur photosynthetic bacteria, fixes carbon dioxide via Calvin-Benson cycle and has been shown previously to express form I and form II ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). The gene cbbM, which encodes the form II enzyme from Rhodopseudomonas palustris, has been subcloned and sequenced. The deduced amino acid sequence is highly with the form II RubisCO from photosynthetic bacteria, including Rhodospirillum rubrum (PDB ID: 9rub), but appears to be more distantly related to the large subunit of the form I RubisCO found in photosynthetic bacteria, chemoautotrophic bacteria and higher plants. Several regions highly conserved among L 8S 8 and L x enzymes correspond with regions previously implicated in catalytic activity and subunit interactions.展开更多
Carbon fixation by soil autotrophic microbes is an overlooked process in organic carbon anabolism,which is potentially affected by biochar.In this study,we quantified the abundance of functional genes cbbL and cbbM,ke...Carbon fixation by soil autotrophic microbes is an overlooked process in organic carbon anabolism,which is potentially affected by biochar.In this study,we quantified the abundance of functional genes cbbL and cbbM,key components of the widely distributed Calvin cycle,and combined this with Ribulose-1,5-bisphosphate carboxylase/oxygenase(RubisCO)enzyme activity assays and high-throughput sequencing of cbbL-and cbbM-harboring microbial communities to investigate the carbon fixation potential,activity,and community structure under biochar application in paddy and upland soils.Results showed that cbbL consistently dominated over cbbM in both paddy and upland soils,with higher abundances in paddy soils,driven by biochar amendment,rice growth stage,and rhizosphere effects.The rhizosphere acted as a hotspot for cbbL and cbbM genes and RubisCO activity in paddy soil.In upland soils,nitrogen availability(NH_(₄)^(+),dissolved organic nitrogen-DON),microbial biomass carbon,and labile carbon and nitrogen pools(dissolved organic carbon,N-acetyl-β-D-glucosaminidase)were consistently associated with cbbL abundance,underscoring their ecological role in soil CO_(2)fixation.In paddy soils,inorganic nitrogen(NH_(₄)^(+),NO_(3)^(⁻),NO_(2)^(⁻)),redox potential(Eh),and urease activity were the main predictors of cbbL abundance and the cbbL/16S ratio,while pH and nitrogen availability(NO_(2)^(⁻),DON)was mostly associated with cbbM/16S ratio.Biochar was the primary driver reshaping the structure of autotrophic microbial communities harboring cbbL and cbbM genes across different soil compartments,including surface soil,rhizosphere,and bulk soil.Pseudomonadota,Cyanobacteriota,Actinomycetota and Chloroflexota were dominant cbbL carriers,while Pseudomonadota,Actinomycetota and Myxococcota predominated in cbbM assemblages across soils.Biochar induced functional differentiation of facultative autotrophic taxa under different RubisCO forms by enhancing the abundance of Rhodopseudomonas in cbbM-bearing communities while decreasing it in cbbL-bearing ones.Furthermore,Calvin cycle-mediated CO_(2)fixation was found to couple with pathways including methylotrophy,methanotrophy,iron oxidation and respiration,nitrogen fixation and reduction,and arsenate reduction and detoxification.Collectively,the results of this study emphasize the importance of soil type,micro-environmental conditions,nitrogen status and the impact of biochar in shaping microbial carbon assimilation via the Calvin cycle pathway and the cbbL and cbbM-harboring microbial community.展开更多
文摘Rhodopseudomonas palustris, one of purple nonsulfur photosynthetic bacteria, fixes carbon dioxide via Calvin-Benson cycle and has been shown previously to express form I and form II ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO). The gene cbbM, which encodes the form II enzyme from Rhodopseudomonas palustris, has been subcloned and sequenced. The deduced amino acid sequence is highly with the form II RubisCO from photosynthetic bacteria, including Rhodospirillum rubrum (PDB ID: 9rub), but appears to be more distantly related to the large subunit of the form I RubisCO found in photosynthetic bacteria, chemoautotrophic bacteria and higher plants. Several regions highly conserved among L 8S 8 and L x enzymes correspond with regions previously implicated in catalytic activity and subunit interactions.
基金the National Natural Science Foundation of China(Grant No.42177107,42307043,21607125)Natural Science Foundation of Anhui Province,China(Grant No.2108085MC85).
文摘Carbon fixation by soil autotrophic microbes is an overlooked process in organic carbon anabolism,which is potentially affected by biochar.In this study,we quantified the abundance of functional genes cbbL and cbbM,key components of the widely distributed Calvin cycle,and combined this with Ribulose-1,5-bisphosphate carboxylase/oxygenase(RubisCO)enzyme activity assays and high-throughput sequencing of cbbL-and cbbM-harboring microbial communities to investigate the carbon fixation potential,activity,and community structure under biochar application in paddy and upland soils.Results showed that cbbL consistently dominated over cbbM in both paddy and upland soils,with higher abundances in paddy soils,driven by biochar amendment,rice growth stage,and rhizosphere effects.The rhizosphere acted as a hotspot for cbbL and cbbM genes and RubisCO activity in paddy soil.In upland soils,nitrogen availability(NH_(₄)^(+),dissolved organic nitrogen-DON),microbial biomass carbon,and labile carbon and nitrogen pools(dissolved organic carbon,N-acetyl-β-D-glucosaminidase)were consistently associated with cbbL abundance,underscoring their ecological role in soil CO_(2)fixation.In paddy soils,inorganic nitrogen(NH_(₄)^(+),NO_(3)^(⁻),NO_(2)^(⁻)),redox potential(Eh),and urease activity were the main predictors of cbbL abundance and the cbbL/16S ratio,while pH and nitrogen availability(NO_(2)^(⁻),DON)was mostly associated with cbbM/16S ratio.Biochar was the primary driver reshaping the structure of autotrophic microbial communities harboring cbbL and cbbM genes across different soil compartments,including surface soil,rhizosphere,and bulk soil.Pseudomonadota,Cyanobacteriota,Actinomycetota and Chloroflexota were dominant cbbL carriers,while Pseudomonadota,Actinomycetota and Myxococcota predominated in cbbM assemblages across soils.Biochar induced functional differentiation of facultative autotrophic taxa under different RubisCO forms by enhancing the abundance of Rhodopseudomonas in cbbM-bearing communities while decreasing it in cbbL-bearing ones.Furthermore,Calvin cycle-mediated CO_(2)fixation was found to couple with pathways including methylotrophy,methanotrophy,iron oxidation and respiration,nitrogen fixation and reduction,and arsenate reduction and detoxification.Collectively,the results of this study emphasize the importance of soil type,micro-environmental conditions,nitrogen status and the impact of biochar in shaping microbial carbon assimilation via the Calvin cycle pathway and the cbbL and cbbM-harboring microbial community.
