The present study investigated the relationship between N-acyl-homoserine lactone（AHL）-based quorum sensing（QS） and the physico-chemical properties of aerobic granules.Stable mature granules were observed in SBR2 ...The present study investigated the relationship between N-acyl-homoserine lactone（AHL）-based quorum sensing（QS） and the physico-chemical properties of aerobic granules.Stable mature granules were observed in SBR2 and SBR3 with average diameters of 0.96,and1.49 mm,respectively. The sludge densities of aerobic granules in SBR2 and SBR3 were1.0246,and 1.0201 g/mL,respectively,which were higher than that of flocculent sludge in SBR1（1.0065 g/mL）. The results showed that the activity of AHL-based QS in SBR2 and SBR3 amounted to 2.4- and 2.1-fold induction,however,that in SBR1 with flocculent sludge was1.6-fold induction. In addition,the results also showed that the activity of AHL-based QS in the three reactors rose in the feast condition,and then dropped with the consumption of substrate. However,the activity of AHL-based QS in these three reactors recovered again in prolonged starvation. Furthermore,the results showed that the enhancement of AHL-based QS favored the extracellular polymeric substance production of microorganisms in activated sludge. Thus,it could be concluded that aerobic granules showed higher AHL-based QS than flocculent sludge,which resulted from the higher sludge density of aerobic granules than flocculent sludge. AHL-based QS was related to the metabolism energy in the feast condition; however,in prolonged starvation,microorganisms would emit more AHL-like molecules to protect themselves to resist starvation. Moreover,the enhancement of AHL-based QS favored the EPS component productivity of the microorganisms in activated sludge,which contributed to maintain the aerobic granular structure.展开更多
As a special biofilm structure,microbial attachment is believed to play an important role in the granulation of aerobic granular activated sludge（AGAS）.This experiment was to investigate the biological effect of Ca^...As a special biofilm structure,microbial attachment is believed to play an important role in the granulation of aerobic granular activated sludge（AGAS）.This experiment was to investigate the biological effect of Ca^2＋,Mg^2＋,Cu^2＋,Fe^2＋,Zn^2＋,and K＋which are the most common ions present in biological wastewater treatment systems,on the microbial attachment of AGAS and flocculent activated sludge（FAS）,from which AGAS is always derived,in order to provide a new strategy for the rapid cultivation and stability control of AGAS.The result showed that attachment biomass of AGAS was about 300%higher than that of FAS without the addition of metal ions.Different metal ions had different effects on the process of microbial attachment.FAS and AGAS reacted differently to the metal ions as well,and in fact,AGAS was more sensitive to the metal ions.Specifically,Ca^2＋,Mg^2＋,and K＋could increase the microbial attachment ability of both AGAS and FAS under appropriate concentrations,Cu^2＋,Fe^2＋,and Zn^2＋were also beneficial to the microbial attachment of FAS at low concentrations,but Cu^2＋,Fe^2＋,and Zn^2＋greatly inhibited the attachment process of AGAS even at extremely low concentrations.In addition,the acylated homoserine lactone（AHL）-based quorum sensing system,the content of extracellular polymeric substances and the relative hydrophobicity of the sludges were greatly influenced by metal ions.As all these parameters had close relationships with the microbial attachment process,the microbial attachment may be affected by changes of these parameters.展开更多
Twelve putative"Chantransia"isolates were collected from six locations across Hubei,Shanxi,Guizhou,and Henan Provinces in China.Their morphological characters were evaluated via the Ward’s method of hierarc...Twelve putative"Chantransia"isolates were collected from six locations across Hubei,Shanxi,Guizhou,and Henan Provinces in China.Their morphological characters were evaluated via the Ward’s method of hierarchical cluster analysis in SPSS software to classify phylogenetic relationships among the isolates.The morphological data revealed that isolate HN31(called group"MALL")was distinct from the other specimens being macroscopic with large vegetative cells and monosporangia(>20μm in diameter).The 11 other isolates were grouped into three clusters,corresponding to the species Audouinella tenella,A.hermannii,and A.pygmaea.The morphological"Chantransia"stage of the species,reportedly belonging to the orders Batrachospermales,Thoreales,and the phylogenetically distant genus Audouinella,are very similar,resulting in the di fficulty to distinguish them based just on morphology.Therefore,molecular analysis of rbc L,UPA,and COI-5 P was conducted to infer the phylogenetic position of all isolates in this study.All"A.tenella"and"A.hermannii"sequences belong to order Batrachospermales,while the isolate HN31 was the"Chantransia"of Thorea hispida.The six other specimens varied morphologically,but they were within the circumscription of"A.pygmaea".All three molecular markers show that all"pygmaea"isolates also represent the"Chantransia"of T.hispida.Furthermore,results from this investigation proposed a new species—Sheathia qinyuanensis,corresponding to the isolates QY1 and QY2.展开更多
Freshwater brown algae have been acknowledged as the least diverse of all groups of freshwater algae. Morphological and molecular investigation were conducted on a freshwater brown alga collected in this study. Morpho...Freshwater brown algae have been acknowledged as the least diverse of all groups of freshwater algae. Morphological and molecular investigation were conducted on a freshwater brown alga collected in this study. Morphological characterization and phylogenetic tree based on the rbcL gene confirmed its attribution to Heribaudiella fluviatilis. The complete organelle genomes of H. fluviatilis were determined and assembled from high-throughput sequencing. A circular tetrad structure of 128,880 bp was identified for the chloroplast, and the mitochondrial genome was assembled as a circle with 43,657 bp in length. This study provides the first and only record of organelle genomic information of the freshwater Phaeophyceae, which are important for understanding the endosymbiosis theories. Concatenated (Bayesian inference, maximum likelihood under MFP and GHOST models) and coalescent methods were used to construct the phylogenetic relationship among secondary plastid-bearing lineages based on organelle genomes. Obvious conflicts were observed in grouping relationships of chloroplast and mitochondrial genomes, even among different evolutionary models and tree-constructing methods. The transcriptome of H. fluviatilis was sequenced and used to construct the phylogenetic relationship among secondary plastid-bearing lineages. The phylogenetic relationships in nuclear and mitochondrial genomes were consistent in grouping CHSR taxa (cryptophytes, haptophytes, stramenopiles and rhizarians) in an independent branch. The phylogenetic relationship constructed from nuclear transcriptomes was highly reliable by owning robust supporting values on each node and was consistent with the serial endosymbiosis theory on evolution of red secondary plastid-derived lineages.展开更多
Given their varied physiological and ecological attributes, phytoplankton frequently exhibit disparate responses to changes in environmental conditions. Therefore, when studying modifications in the structure of a phy...Given their varied physiological and ecological attributes, phytoplankton frequently exhibit disparate responses to changes in environmental conditions. Therefore, when studying modifications in the structure of a phytoplankton community, it is necessary to consider such differences and investigate the underlying mechanisms. Through a field sampling study of 26 lakes, we found that the differing responses of phytoplankton to changes in environmental factors were partly related to their genome size. The Cyanobacteria and Chrysophyta, which possess smaller genomes, exhibited a relatively low degree of sensitivity to alterations in nutrient concentrations. However, they demonstrated a stronger dependence on the metabolic processes of environmental microorganisms compared to other phytoplankton with larger genomes. Furthermore, the Cyanobacteria and Chrysophyta were more closely associated with environmental nutrients and water chemistry and were more actively involved in interspecific interactions among phytoplankton. By randomly deleting sample points, we verified the generality of the above conclusions. However, more refined grouping analyses indicate that diatoms exhibited different ecological characteristics due to their physiological and morphology. The present study offers new insights into the mechanisms underlying the ecological adaptations of phytoplankton and may provide new guidance for the management of Cyanobacterial blooms. Further studies could take a more refined approach to investigate the effect of phytoplankton “effective genome size” on their adaptive capacity.展开更多
Background Algae play important roles in urban river ecosystems and are the cornerstones of most water quality monitoring programs.Thus,a better understanding of algal community dynamics is needed to support sustainab...Background Algae play important roles in urban river ecosystems and are the cornerstones of most water quality monitoring programs.Thus,a better understanding of algal community dynamics is needed to support sustainable management of water resources in urban rivers.Results In this study,we quantifed the seasonal variations in planktonic and periphytic algal community structure in the highly urban Fenhe River and identifed environmental factors afecting algal community structure and diversity.We monitored planktonic(drifting)and periphytic(attached)algal communities in the Taiyuan section of the Fenhe River over one year.The results indicated that Cyanophyta was the dominant phylum in both communities,followed by Bacillariophyta and Chlorophyta.Signifcant diferences were observed in the composition of the planktonic and periphytic algal communities.In particular,the periphytic algal community was more diverse than the planktonic community.Water temperature and pH were the main environmental factors afecting planktonic and periphytic algal community structure,respectively,while nutrients were the most signifcant factor afecting planktonic and periphytic algal diversity.Ecological modeling indicated that the variations in the algal communities of the Fenhe River are mainly driven by stochastic processes.A co-occurrence network developed for the communities displayed positive interactions between the planktonic and periphytic algae.Conclusions These fndings deepen our understanding of the seasonal interaction between planktonic and periphytic algae and the driving factors afecting community structure in the Fenhe River.They also provide a theoretical basis for the managing and protecting water resources in urban river ecosystems.展开更多
基金supported by the National Natural Science Found of China (No.51078036)
文摘The present study investigated the relationship between N-acyl-homoserine lactone（AHL）-based quorum sensing（QS） and the physico-chemical properties of aerobic granules.Stable mature granules were observed in SBR2 and SBR3 with average diameters of 0.96,and1.49 mm,respectively. The sludge densities of aerobic granules in SBR2 and SBR3 were1.0246,and 1.0201 g/mL,respectively,which were higher than that of flocculent sludge in SBR1（1.0065 g/mL）. The results showed that the activity of AHL-based QS in SBR2 and SBR3 amounted to 2.4- and 2.1-fold induction,however,that in SBR1 with flocculent sludge was1.6-fold induction. In addition,the results also showed that the activity of AHL-based QS in the three reactors rose in the feast condition,and then dropped with the consumption of substrate. However,the activity of AHL-based QS in these three reactors recovered again in prolonged starvation. Furthermore,the results showed that the enhancement of AHL-based QS favored the extracellular polymeric substance production of microorganisms in activated sludge. Thus,it could be concluded that aerobic granules showed higher AHL-based QS than flocculent sludge,which resulted from the higher sludge density of aerobic granules than flocculent sludge. AHL-based QS was related to the metabolism energy in the feast condition; however,in prolonged starvation,microorganisms would emit more AHL-like molecules to protect themselves to resist starvation. Moreover,the enhancement of AHL-based QS favored the EPS component productivity of the microorganisms in activated sludge,which contributed to maintain the aerobic granular structure.
基金supported by the National Natural Science Foundation of China (No. 51578069)
文摘As a special biofilm structure,microbial attachment is believed to play an important role in the granulation of aerobic granular activated sludge（AGAS）.This experiment was to investigate the biological effect of Ca^2＋,Mg^2＋,Cu^2＋,Fe^2＋,Zn^2＋,and K＋which are the most common ions present in biological wastewater treatment systems,on the microbial attachment of AGAS and flocculent activated sludge（FAS）,from which AGAS is always derived,in order to provide a new strategy for the rapid cultivation and stability control of AGAS.The result showed that attachment biomass of AGAS was about 300%higher than that of FAS without the addition of metal ions.Different metal ions had different effects on the process of microbial attachment.FAS and AGAS reacted differently to the metal ions as well,and in fact,AGAS was more sensitive to the metal ions.Specifically,Ca^2＋,Mg^2＋,and K＋could increase the microbial attachment ability of both AGAS and FAS under appropriate concentrations,Cu^2＋,Fe^2＋,and Zn^2＋were also beneficial to the microbial attachment of FAS at low concentrations,but Cu^2＋,Fe^2＋,and Zn^2＋greatly inhibited the attachment process of AGAS even at extremely low concentrations.In addition,the acylated homoserine lactone（AHL）-based quorum sensing system,the content of extracellular polymeric substances and the relative hydrophobicity of the sludges were greatly influenced by metal ions.As all these parameters had close relationships with the microbial attachment process,the microbial attachment may be affected by changes of these parameters.
基金Supported by the National Natural Science Foundation of China(Nos.31670208,41871037 to Shulian XIE,and No.31800172 to Fangru NAN)the Fund for Shanxi“1331 Project”Key Innovative Research Team。
文摘Twelve putative"Chantransia"isolates were collected from six locations across Hubei,Shanxi,Guizhou,and Henan Provinces in China.Their morphological characters were evaluated via the Ward’s method of hierarchical cluster analysis in SPSS software to classify phylogenetic relationships among the isolates.The morphological data revealed that isolate HN31(called group"MALL")was distinct from the other specimens being macroscopic with large vegetative cells and monosporangia(>20μm in diameter).The 11 other isolates were grouped into three clusters,corresponding to the species Audouinella tenella,A.hermannii,and A.pygmaea.The morphological"Chantransia"stage of the species,reportedly belonging to the orders Batrachospermales,Thoreales,and the phylogenetically distant genus Audouinella,are very similar,resulting in the di fficulty to distinguish them based just on morphology.Therefore,molecular analysis of rbc L,UPA,and COI-5 P was conducted to infer the phylogenetic position of all isolates in this study.All"A.tenella"and"A.hermannii"sequences belong to order Batrachospermales,while the isolate HN31 was the"Chantransia"of Thorea hispida.The six other specimens varied morphologically,but they were within the circumscription of"A.pygmaea".All three molecular markers show that all"pygmaea"isolates also represent the"Chantransia"of T.hispida.Furthermore,results from this investigation proposed a new species—Sheathia qinyuanensis,corresponding to the isolates QY1 and QY2.
基金funded by the National Natural Science Foundation of China(No.31800172 to F.R.Nan,No.32170204 to S.L.Xie,No.32270220 and U22A20445 to J.Feng)the Excellent Achievement Cultivation Project of Higher education in Shanxi(No.2020KJ029).
文摘Freshwater brown algae have been acknowledged as the least diverse of all groups of freshwater algae. Morphological and molecular investigation were conducted on a freshwater brown alga collected in this study. Morphological characterization and phylogenetic tree based on the rbcL gene confirmed its attribution to Heribaudiella fluviatilis. The complete organelle genomes of H. fluviatilis were determined and assembled from high-throughput sequencing. A circular tetrad structure of 128,880 bp was identified for the chloroplast, and the mitochondrial genome was assembled as a circle with 43,657 bp in length. This study provides the first and only record of organelle genomic information of the freshwater Phaeophyceae, which are important for understanding the endosymbiosis theories. Concatenated (Bayesian inference, maximum likelihood under MFP and GHOST models) and coalescent methods were used to construct the phylogenetic relationship among secondary plastid-bearing lineages based on organelle genomes. Obvious conflicts were observed in grouping relationships of chloroplast and mitochondrial genomes, even among different evolutionary models and tree-constructing methods. The transcriptome of H. fluviatilis was sequenced and used to construct the phylogenetic relationship among secondary plastid-bearing lineages. The phylogenetic relationships in nuclear and mitochondrial genomes were consistent in grouping CHSR taxa (cryptophytes, haptophytes, stramenopiles and rhizarians) in an independent branch. The phylogenetic relationship constructed from nuclear transcriptomes was highly reliable by owning robust supporting values on each node and was consistent with the serial endosymbiosis theory on evolution of red secondary plastid-derived lineages.
基金funded by the National Natural Science Foundation of China(No.32270220 and U22A20445 to Jia Feng)the Excellent Achievement Cultivation Project of Higher education in Shanxi(No.2020KJ029)the Nature Science Foundation of Shanxi Province(No.202203021211313).
文摘Given their varied physiological and ecological attributes, phytoplankton frequently exhibit disparate responses to changes in environmental conditions. Therefore, when studying modifications in the structure of a phytoplankton community, it is necessary to consider such differences and investigate the underlying mechanisms. Through a field sampling study of 26 lakes, we found that the differing responses of phytoplankton to changes in environmental factors were partly related to their genome size. The Cyanobacteria and Chrysophyta, which possess smaller genomes, exhibited a relatively low degree of sensitivity to alterations in nutrient concentrations. However, they demonstrated a stronger dependence on the metabolic processes of environmental microorganisms compared to other phytoplankton with larger genomes. Furthermore, the Cyanobacteria and Chrysophyta were more closely associated with environmental nutrients and water chemistry and were more actively involved in interspecific interactions among phytoplankton. By randomly deleting sample points, we verified the generality of the above conclusions. However, more refined grouping analyses indicate that diatoms exhibited different ecological characteristics due to their physiological and morphology. The present study offers new insights into the mechanisms underlying the ecological adaptations of phytoplankton and may provide new guidance for the management of Cyanobacterial blooms. Further studies could take a more refined approach to investigate the effect of phytoplankton “effective genome size” on their adaptive capacity.
基金funded by the National Nature Science Foundation of China(Nos.32270220 and U22A20445 to Jia Feng)the Excellent Achievement Cultivation Project of Higher education in Shanxi(No.2020KJ029)the Nature Science Foundation of Shanxi Province(No.202203021211313).
文摘Background Algae play important roles in urban river ecosystems and are the cornerstones of most water quality monitoring programs.Thus,a better understanding of algal community dynamics is needed to support sustainable management of water resources in urban rivers.Results In this study,we quantifed the seasonal variations in planktonic and periphytic algal community structure in the highly urban Fenhe River and identifed environmental factors afecting algal community structure and diversity.We monitored planktonic(drifting)and periphytic(attached)algal communities in the Taiyuan section of the Fenhe River over one year.The results indicated that Cyanophyta was the dominant phylum in both communities,followed by Bacillariophyta and Chlorophyta.Signifcant diferences were observed in the composition of the planktonic and periphytic algal communities.In particular,the periphytic algal community was more diverse than the planktonic community.Water temperature and pH were the main environmental factors afecting planktonic and periphytic algal community structure,respectively,while nutrients were the most signifcant factor afecting planktonic and periphytic algal diversity.Ecological modeling indicated that the variations in the algal communities of the Fenhe River are mainly driven by stochastic processes.A co-occurrence network developed for the communities displayed positive interactions between the planktonic and periphytic algae.Conclusions These fndings deepen our understanding of the seasonal interaction between planktonic and periphytic algae and the driving factors afecting community structure in the Fenhe River.They also provide a theoretical basis for the managing and protecting water resources in urban river ecosystems.
