Although biofilm formation may promote growth,biofilms are not always beneficial to their hosts.The biofilm formation characteristics of Bacillus cereus WPySW2 and its changes at different temperatures were studied.Re...Although biofilm formation may promote growth,biofilms are not always beneficial to their hosts.The biofilm formation characteristics of Bacillus cereus WPySW2 and its changes at different temperatures were studied.Results show that B.cereus WPySW2 promoted the growth of Neoporphyra haitanensis(an economically cultivated seaweed)at 20℃ but accelerated algal rot at 28℃.Thicker B.cereus WPySW2 biofilms covered the surface of N.haitanensis thalli at 28℃,which hindered material exchange between the algae and surrounding environment,inhibited algal photosynthesis and respiration,and accelerated algal decay.Compared with planktonic bacteria,mature biofilm cells had lower energy consumption and metabolic levels.The biofilm metabolic characteristics of B.cereus WPySW2 changed significantly with temperature.High temperature accelerated biofilm maturation,which made it thicker and more stable,allowing the bacteria to easily adapt to environmental changes and obtain greater benefits from their host.High temperature did not affect the production or increased the abundance of toxic metabolites,indicating that the negative effects of B.cereus WPySW2 on algae were not caused by toxins.This study shows that increased temperature can transform a harmless bacterium into a detrimental one,demonstrating that temperature may change the ecological function of phycospheric bacteria by affecting their morphology and metabolism.展开更多
Abstract Objective To investigate the theoretical model of the three-dimensional structure of mosquitocida Cry3OCa2 and its molecular docking with N-acetylgalactosamine. Methods The theoretical model of Cry30Ca2 was t...Abstract Objective To investigate the theoretical model of the three-dimensional structure of mosquitocida Cry3OCa2 and its molecular docking with N-acetylgalactosamine. Methods The theoretical model of Cry30Ca2 was the Cry4Ba. Docking studies were performed N-acetylgalactosamine on the putative receptor. predicted by homology modeling on the structure of to investigate the interaction of Cry3OCa2 with Results Cry3OCa2 toxin is a rather compact molecule composed of three distinct domains and has approximate overall dimensions of 95 by 75 by 60A. Domain I is a helix bundle, Domain Ⅱ consists of three antiparallel β-sheets, Domain Ⅲ is composed of two β-sheets that adopt a 13-sandwich fold. Residue 32111e in loop1, residues 342Gin 343Thr and 345Gin in loop2, residue 393Tyr in loop3 of Cry3OCa2 are responsible for the interactions with GalNAc via 7 hydrogen bonds, 6 of them were related to the oxygen atoms of hydroxyls of the ligand, and one to the nitrogen of the ligand. Conclusion The 3D structure of Cry3OCa2 resembles the previously reported Cry toxin structures but shows still some distinctions. Several residues in the loops of the apex of domain Ⅱ are responsible for the interactions with N-acetylgalactosamine.展开更多
Since 1996, transgenic Bacillus thuringiensis(Bt) cotton has been commercially grown in numerous countries in an effort to stem the losses caused by key lepidopteran pests. However, the development of pest resistance ...Since 1996, transgenic Bacillus thuringiensis(Bt) cotton has been commercially grown in numerous countries in an effort to stem the losses caused by key lepidopteran pests. However, the development of pest resistance to Bt toxins has jeopardized the continued utilization of Bt cotton. As a strategy designed to circumvent the development of resistance, Bt cotton varieties expressing two or more toxins targeting the same pest have been introduced. Nevertheless, from the perspective of long-term planting of Bt cotton, the potential risk of cross-resistance to these Bt toxins is a threat that cannot be ignored. In this paper, we review current research(including that based on the analysis of protein binding sites and resistance genes) on the resistance of cotton bollworm(Helicoverpa armigera) to the Bt toxins Cry1 Ac and Cry2 Ab and the interrelationship between these toxins. On the basis of existing evidence, we assume that the actions of Cry1 Ac and Cry2 Ab against cotton bollworm are not completely independent, and then propose the "resistance-associated gene mutation potential hypothesis". Although the mechanisms underlying the resistance of pests to Bt toxins are yet to be comprehensively elucidated, this hypothesis could undoubtedly have important implications for adopting "pyramid" strategy in the future. Further research is recommended to devise strategies to retard the development of H. armigera resistance to Bt cotton, either using different Bt toxins or their various combinations.展开更多
The main aroma component of Luzhou-flavor Liquor is ethyl caproate, which is combined with appropriate amount of ethyl butyrate, ethyl acetate, ethyl lactate and so on. By adding the marine bacillus BC-2 (Accession nu...The main aroma component of Luzhou-flavor Liquor is ethyl caproate, which is combined with appropriate amount of ethyl butyrate, ethyl acetate, ethyl lactate and so on. By adding the marine bacillus BC-2 (Accession number: MK811408) to substrate sludge, the bacillus complex bacterial liquid (pit Mud Functional Bacterial liquid) has been modified. The complex bacterial liquid was used in the production of Luzhou-flavor Liquor and it dramatically promoted the content of health-beneficial ingredients in the new workshop. These results demonstrated that the marine bacillus BC-2 can effectively improve the quality and health benefit of Luzhou-flavor Liquor.展开更多
A strain secreting a strongly acidic polysaccharide flocculating agent was isolated from activated sludge, and identified as Bacillus brevis. The bioflocculant was produced by RL-2 during the late logarithmic growth i...A strain secreting a strongly acidic polysaccharide flocculating agent was isolated from activated sludge, and identified as Bacillus brevis. The bioflocculant was produced by RL-2 during the late logarithmic growth in the batch culture and was recovered from supernatant by ethanol precipitation. The bioflocculant is thermo-stable as its activity remains stable after heated at 100 °C for 45 min. Its flocculating activity with kaolin suspensions was stimulated by the addition of Ca2+, Al3+ and Cu2+. The flocculant consists of glucose, mannose, and galacturonic acid. Its average molecular mass was estimated to be approximately 2.86×105 by the method of viscosity. The flocculant aggregates various inorganic and organic compounds in solution.展开更多
sodA2-encoding manganese-containing superoxide dismutase(MnSOD2)in Bacillus cereus 905 plays an essential role in antioxidative stress,nutrition utilization,rhizosphere and phyllosphere colonization.However,the genes ...sodA2-encoding manganese-containing superoxide dismutase(MnSOD2)in Bacillus cereus 905 plays an essential role in antioxidative stress,nutrition utilization,rhizosphere and phyllosphere colonization.However,the genes involved in regulating the sod A2 expression have not been clearly elucidated in B.cereus.In this study,a genome-wide random insertion mutagenesis was constructed by using transposon TnYLB-1 to identify novel genes regulating the sodA2 expression.Seven mutants that changed the sodA2 expression at both m RNA and protein levels were finally obtained.Sequence analysis and BLAST data showed that the genes disrupted by TnYLB-1 in B.cereus 905 shared high conservations with those in the B.cereus type strain,ATCC 14579.These genes encode heat-inducible transcription repressor,chloride channel protein,recombinase A,ferrous iron transport protein,nucleoside diphosphate kinase,and histidine ammonia-lyase.Besides,we also provided the evidence that the genes regulating the sodA2 expression could influence colonization ability of B.cereus 905 on wheat roots.Specifically,those genes downregulating the sodA2 expression significantly reduced bacterial colonization on wheat roots,and mutants with increased MnSOD2 activities could enhance bacterial population densities on wheat roots to a certain degree.Our work provided information that multiple genes are involved in MnSOD2 production and wheat root colonization.The molecular regulatory pathways through which these genes modulate the sod A2 expression and root colonization need to be investigated extensively in the future.展开更多
基金Supported by the Zhejiang Province Nature Science Foundation of China(No.LY22C190002)the National Natural Science Foundation of China(Nos.31772871,31872540)+4 种基金the Major Scientific and Technological Project of Zhejiang Province(No.2021C02069-9)the Major Scientific and Technological Project of Ningbo(Nos.2021Z004,2021Z103)the Scientific and Technological Project of Ningbo(No.2021S063)the China Agriculture Research System of MOF and MARAthe K.C.Wong Magna Fund of Ningbo University。
文摘Although biofilm formation may promote growth,biofilms are not always beneficial to their hosts.The biofilm formation characteristics of Bacillus cereus WPySW2 and its changes at different temperatures were studied.Results show that B.cereus WPySW2 promoted the growth of Neoporphyra haitanensis(an economically cultivated seaweed)at 20℃ but accelerated algal rot at 28℃.Thicker B.cereus WPySW2 biofilms covered the surface of N.haitanensis thalli at 28℃,which hindered material exchange between the algae and surrounding environment,inhibited algal photosynthesis and respiration,and accelerated algal decay.Compared with planktonic bacteria,mature biofilm cells had lower energy consumption and metabolic levels.The biofilm metabolic characteristics of B.cereus WPySW2 changed significantly with temperature.High temperature accelerated biofilm maturation,which made it thicker and more stable,allowing the bacteria to easily adapt to environmental changes and obtain greater benefits from their host.High temperature did not affect the production or increased the abundance of toxic metabolites,indicating that the negative effects of B.cereus WPySW2 on algae were not caused by toxins.This study shows that increased temperature can transform a harmless bacterium into a detrimental one,demonstrating that temperature may change the ecological function of phycospheric bacteria by affecting their morphology and metabolism.
基金supported by grants from Hunan Provincial Natural Science Foundation of China(No.12JJ3021)the National Natural Science Foundation of China(No.30670052,30570050)863 Program of China(2006AA02Z187)
文摘Abstract Objective To investigate the theoretical model of the three-dimensional structure of mosquitocida Cry3OCa2 and its molecular docking with N-acetylgalactosamine. Methods The theoretical model of Cry30Ca2 was the Cry4Ba. Docking studies were performed N-acetylgalactosamine on the putative receptor. predicted by homology modeling on the structure of to investigate the interaction of Cry3OCa2 with Results Cry3OCa2 toxin is a rather compact molecule composed of three distinct domains and has approximate overall dimensions of 95 by 75 by 60A. Domain I is a helix bundle, Domain Ⅱ consists of three antiparallel β-sheets, Domain Ⅲ is composed of two β-sheets that adopt a 13-sandwich fold. Residue 32111e in loop1, residues 342Gin 343Thr and 345Gin in loop2, residue 393Tyr in loop3 of Cry3OCa2 are responsible for the interactions with GalNAc via 7 hydrogen bonds, 6 of them were related to the oxygen atoms of hydroxyls of the ligand, and one to the nitrogen of the ligand. Conclusion The 3D structure of Cry3OCa2 resembles the previously reported Cry toxin structures but shows still some distinctions. Several residues in the loops of the apex of domain Ⅱ are responsible for the interactions with N-acetylgalactosamine.
基金This study was supported by the National Natural Science Foundation of China(U1803233).The authors thank Prof.Kathreen RUCKSTUHL and Dr.WANG Muyang for their helpful suggestions on this manuscript.
文摘Since 1996, transgenic Bacillus thuringiensis(Bt) cotton has been commercially grown in numerous countries in an effort to stem the losses caused by key lepidopteran pests. However, the development of pest resistance to Bt toxins has jeopardized the continued utilization of Bt cotton. As a strategy designed to circumvent the development of resistance, Bt cotton varieties expressing two or more toxins targeting the same pest have been introduced. Nevertheless, from the perspective of long-term planting of Bt cotton, the potential risk of cross-resistance to these Bt toxins is a threat that cannot be ignored. In this paper, we review current research(including that based on the analysis of protein binding sites and resistance genes) on the resistance of cotton bollworm(Helicoverpa armigera) to the Bt toxins Cry1 Ac and Cry2 Ab and the interrelationship between these toxins. On the basis of existing evidence, we assume that the actions of Cry1 Ac and Cry2 Ab against cotton bollworm are not completely independent, and then propose the "resistance-associated gene mutation potential hypothesis". Although the mechanisms underlying the resistance of pests to Bt toxins are yet to be comprehensively elucidated, this hypothesis could undoubtedly have important implications for adopting "pyramid" strategy in the future. Further research is recommended to devise strategies to retard the development of H. armigera resistance to Bt cotton, either using different Bt toxins or their various combinations.
文摘The main aroma component of Luzhou-flavor Liquor is ethyl caproate, which is combined with appropriate amount of ethyl butyrate, ethyl acetate, ethyl lactate and so on. By adding the marine bacillus BC-2 (Accession number: MK811408) to substrate sludge, the bacillus complex bacterial liquid (pit Mud Functional Bacterial liquid) has been modified. The complex bacterial liquid was used in the production of Luzhou-flavor Liquor and it dramatically promoted the content of health-beneficial ingredients in the new workshop. These results demonstrated that the marine bacillus BC-2 can effectively improve the quality and health benefit of Luzhou-flavor Liquor.
文摘A strain secreting a strongly acidic polysaccharide flocculating agent was isolated from activated sludge, and identified as Bacillus brevis. The bioflocculant was produced by RL-2 during the late logarithmic growth in the batch culture and was recovered from supernatant by ethanol precipitation. The bioflocculant is thermo-stable as its activity remains stable after heated at 100 °C for 45 min. Its flocculating activity with kaolin suspensions was stimulated by the addition of Ca2+, Al3+ and Cu2+. The flocculant consists of glucose, mannose, and galacturonic acid. Its average molecular mass was estimated to be approximately 2.86×105 by the method of viscosity. The flocculant aggregates various inorganic and organic compounds in solution.
基金the grants from the National Natural Science Foundation of China(31701860)the Program of Science and Technology of Beijing,China(Z191100004019025)。
文摘sodA2-encoding manganese-containing superoxide dismutase(MnSOD2)in Bacillus cereus 905 plays an essential role in antioxidative stress,nutrition utilization,rhizosphere and phyllosphere colonization.However,the genes involved in regulating the sod A2 expression have not been clearly elucidated in B.cereus.In this study,a genome-wide random insertion mutagenesis was constructed by using transposon TnYLB-1 to identify novel genes regulating the sodA2 expression.Seven mutants that changed the sodA2 expression at both m RNA and protein levels were finally obtained.Sequence analysis and BLAST data showed that the genes disrupted by TnYLB-1 in B.cereus 905 shared high conservations with those in the B.cereus type strain,ATCC 14579.These genes encode heat-inducible transcription repressor,chloride channel protein,recombinase A,ferrous iron transport protein,nucleoside diphosphate kinase,and histidine ammonia-lyase.Besides,we also provided the evidence that the genes regulating the sodA2 expression could influence colonization ability of B.cereus 905 on wheat roots.Specifically,those genes downregulating the sodA2 expression significantly reduced bacterial colonization on wheat roots,and mutants with increased MnSOD2 activities could enhance bacterial population densities on wheat roots to a certain degree.Our work provided information that multiple genes are involved in MnSOD2 production and wheat root colonization.The molecular regulatory pathways through which these genes modulate the sod A2 expression and root colonization need to be investigated extensively in the future.
