A unicellular-colonial cyanobacterium,designated“BRSZ,”was isolated from a neutral-alkaline hot spring in Thai-land.Morphological characterization revealed distinctive features consistent with those of the genus Glo...A unicellular-colonial cyanobacterium,designated“BRSZ,”was isolated from a neutral-alkaline hot spring in Thai-land.Morphological characterization revealed distinctive features consistent with those of the genus Gloeocapsa.Physiological assessments demonstrated that BRSZ is a moderately thermophilic and halotolerant cyanobacterium with the potential for chemoheterotrophic growth in dark conditions.Molecular phylogenetic analysis based on 16S ribosomal RNA(rRNA)gene sequences placed BRSZ within a well-defined Gloeocapsa clade,a finding cor-roborated by 16S-23S internal transcribed spacer(ITS)rRNA secondary structure analyses.Genome compar-isons,including average nucleotide identity(ANI),genome-to-genome distance(GGD),and digital DNA-DNA hybridization(dDDH),between strain BRSZ and closely related taxa showed an ANI value of 95.45%,near the lower boundary of the species delineation threshold(95-96%).A GGD of 0.0374(>0.0258)and dDDH of 69%(<70%)further supported genomic differentiation.Genome-based analysis revealed a mycosporine-like amino acid biosynthetic gene cluster likely involved in sunscreen compound production.Cultivation-based production of a UV-absorbing compound confirmed the functional relevance of this gene cluster.These findings expand the described diversity within the Gloeocapsa complex and enhance our understanding of the taxonomy of this group.In addition,they underscored the importance of hot spring environments as sources of novel extremophiles.展开更多
Marine fuel oil(MFO)spills in tropical coastal environments are under-characterized despite increasing risk from maritime activities.Microbial and geochemical responses to the June 2024 Marine Honour MFO spill on Sing...Marine fuel oil(MFO)spills in tropical coastal environments are under-characterized despite increasing risk from maritime activities.Microbial and geochemical responses to the June 2024 Marine Honour MFO spill on Singapore's intertidal sediments were analyzed in real time over 185 days.Using metagenomics and hydrocarbon profiling,microbial community shifts and hydrocarbon degradation were quantified across visibly oiled(high-impact)and clean(low-impact)sites.Microbiomes at all sites adapted rapidly to the spill through increased diversity and abundance of genes encoding alkane and aromatic compound degradation,detoxification,and biosurfactant production.The dominant hydrocarbon-degrading bacteria differed markedly from those reported in other crude oil spills and in regions with different climates.Oil deposition intensity strongly influenced microbial succession and hydrocarbon-degrading gene profiles,and this reflected early toxicity constraints in heavily oiled areas.The persistence of hydrocarbon degradation genes beyond hydrocarbon detection in sediments suggested long-term functional priming may occur.The study provides novel genome-resolved insight into the microbial response to MFO pollution,advances understanding of marine environmental biodegradation,and provides urgently needed baseline data for oil spill response strategies in Southeast Asia and beyond.展开更多
基金supported in part by the following research grants:Thai-land Science research and Innovation fund Chulalongkorn University(FOOD_FF_68_121_2300_022)(to RWS)the Singapore Ministry of Ed-ucation MOE-T2EP30123-0007(to RWS&SBP)+1 种基金the Research Institute of Meijo University(to HK)Postdoctoral Fellowship,the Second Century Fund(C2F),Chulalongkorn University(to SS).
文摘A unicellular-colonial cyanobacterium,designated“BRSZ,”was isolated from a neutral-alkaline hot spring in Thai-land.Morphological characterization revealed distinctive features consistent with those of the genus Gloeocapsa.Physiological assessments demonstrated that BRSZ is a moderately thermophilic and halotolerant cyanobacterium with the potential for chemoheterotrophic growth in dark conditions.Molecular phylogenetic analysis based on 16S ribosomal RNA(rRNA)gene sequences placed BRSZ within a well-defined Gloeocapsa clade,a finding cor-roborated by 16S-23S internal transcribed spacer(ITS)rRNA secondary structure analyses.Genome compar-isons,including average nucleotide identity(ANI),genome-to-genome distance(GGD),and digital DNA-DNA hybridization(dDDH),between strain BRSZ and closely related taxa showed an ANI value of 95.45%,near the lower boundary of the species delineation threshold(95-96%).A GGD of 0.0374(>0.0258)and dDDH of 69%(<70%)further supported genomic differentiation.Genome-based analysis revealed a mycosporine-like amino acid biosynthetic gene cluster likely involved in sunscreen compound production.Cultivation-based production of a UV-absorbing compound confirmed the functional relevance of this gene cluster.These findings expand the described diversity within the Gloeocapsa complex and enhance our understanding of the taxonomy of this group.In addition,they underscored the importance of hot spring environments as sources of novel extremophiles.
基金funded by the Singapore Ministry of Education(grant number MOE-T2EP30122-0003)the Singapore National Parks Board for granting a research permit for the work(permit number NP/RP24-155).
文摘Marine fuel oil(MFO)spills in tropical coastal environments are under-characterized despite increasing risk from maritime activities.Microbial and geochemical responses to the June 2024 Marine Honour MFO spill on Singapore's intertidal sediments were analyzed in real time over 185 days.Using metagenomics and hydrocarbon profiling,microbial community shifts and hydrocarbon degradation were quantified across visibly oiled(high-impact)and clean(low-impact)sites.Microbiomes at all sites adapted rapidly to the spill through increased diversity and abundance of genes encoding alkane and aromatic compound degradation,detoxification,and biosurfactant production.The dominant hydrocarbon-degrading bacteria differed markedly from those reported in other crude oil spills and in regions with different climates.Oil deposition intensity strongly influenced microbial succession and hydrocarbon-degrading gene profiles,and this reflected early toxicity constraints in heavily oiled areas.The persistence of hydrocarbon degradation genes beyond hydrocarbon detection in sediments suggested long-term functional priming may occur.The study provides novel genome-resolved insight into the microbial response to MFO pollution,advances understanding of marine environmental biodegradation,and provides urgently needed baseline data for oil spill response strategies in Southeast Asia and beyond.
