Twenty-nine facultative anaerobic cellulose-degrading bacteria were isolated from soil, rumen fluid, rumen residues and diet of dairy cow. Based on 16 Sr DNA analysis by BLAST algorithm method, the results showed that...Twenty-nine facultative anaerobic cellulose-degrading bacteria were isolated from soil, rumen fluid, rumen residues and diet of dairy cow. Based on 16 Sr DNA analysis by BLAST algorithm method, the results showed that most of the strains were Bacillus genera, and six of the 29 strains were bigger than 10 mm of diameter of clear zones. For them, two strains were isolated from rumen fluid(L5 and L7) and other two were isolated from rumen residue(N5 and N9), while others were isolated from soil(T1) and diet(S6), respectively. Strains from rumen fluid and residue had higher activities of FPCase and CMCase, but lower β-glucosidases.展开更多
The human intestinal microbiota that comprise over 1,000 species thrive in dark and anaerobic environments.They are recognized for the production of diverse low-molecular-weight metabolites crucial to human health and...The human intestinal microbiota that comprise over 1,000 species thrive in dark and anaerobic environments.They are recognized for the production of diverse low-molecular-weight metabolites crucial to human health and diseases.Carotenoids,low-molecular-weight pigments known for their antioxidative activity,are delivered to humans through oral intake.However,it remains unclear whether human intestinal bacteria biosynthesize carotenoids as part of the in-situ microbiota.In this study,we investigated carotenoid synthesis genes in vari-ous human gut and probiotic bacteria.As a result,novel candidates,the crtM and crtN genes,were identified in the carbon monoxide-utilizing gut anaerobe Eubacterium limosum and the lactic acid bacterium Leuconostoc mesenteroides subsp.mesenteroides.These gene candidates were isolated,introduced into Escherichia coli,which synthesized a carotenoid substrate,and cultured aerobically.Structural analysis of the resulting carotenoids re-vealed that the crtM and crtN gene candidates of E.limosum and L.mesenteroides mediate the production of 4,4′-diaponeurosporene through 15-cis-4,4′-diapophytoene.Evaluation of the crtE-homologous genes in these bacteria indicated their non-functionality for C40-carotenoid production.E.limosum and L.mesenteroides,along with the known carotenogenic lactic acid bacterium Lactiplantibacillus plantarum,were observed to produce no carotenoids under strictly anaerobic conditions.The two lactic acid bacteria synthesized detectable levels of 4,4′-diaponeurosporene under semi-aerobic conditions.The findings highlight that the obligate anaerobe E.limo-sum retains aerobically functional C30-carotenoid biosynthesis genes,potentially with no immediate self-utility,suggesting an evolutionary direction in carotenoid biosynthesis.(229 words)展开更多
基金Supported by Northeast Agricultural University Innovation Funding for Postgraduate(yjscx14007)China Agriculture Research System(CARS-37)
文摘Twenty-nine facultative anaerobic cellulose-degrading bacteria were isolated from soil, rumen fluid, rumen residues and diet of dairy cow. Based on 16 Sr DNA analysis by BLAST algorithm method, the results showed that most of the strains were Bacillus genera, and six of the 29 strains were bigger than 10 mm of diameter of clear zones. For them, two strains were isolated from rumen fluid(L5 and L7) and other two were isolated from rumen residue(N5 and N9), while others were isolated from soil(T1) and diet(S6), respectively. Strains from rumen fluid and residue had higher activities of FPCase and CMCase, but lower β-glucosidases.
文摘The human intestinal microbiota that comprise over 1,000 species thrive in dark and anaerobic environments.They are recognized for the production of diverse low-molecular-weight metabolites crucial to human health and diseases.Carotenoids,low-molecular-weight pigments known for their antioxidative activity,are delivered to humans through oral intake.However,it remains unclear whether human intestinal bacteria biosynthesize carotenoids as part of the in-situ microbiota.In this study,we investigated carotenoid synthesis genes in vari-ous human gut and probiotic bacteria.As a result,novel candidates,the crtM and crtN genes,were identified in the carbon monoxide-utilizing gut anaerobe Eubacterium limosum and the lactic acid bacterium Leuconostoc mesenteroides subsp.mesenteroides.These gene candidates were isolated,introduced into Escherichia coli,which synthesized a carotenoid substrate,and cultured aerobically.Structural analysis of the resulting carotenoids re-vealed that the crtM and crtN gene candidates of E.limosum and L.mesenteroides mediate the production of 4,4′-diaponeurosporene through 15-cis-4,4′-diapophytoene.Evaluation of the crtE-homologous genes in these bacteria indicated their non-functionality for C40-carotenoid production.E.limosum and L.mesenteroides,along with the known carotenogenic lactic acid bacterium Lactiplantibacillus plantarum,were observed to produce no carotenoids under strictly anaerobic conditions.The two lactic acid bacteria synthesized detectable levels of 4,4′-diaponeurosporene under semi-aerobic conditions.The findings highlight that the obligate anaerobe E.limo-sum retains aerobically functional C30-carotenoid biosynthesis genes,potentially with no immediate self-utility,suggesting an evolutionary direction in carotenoid biosynthesis.(229 words)
