The northern South China Sea,including the Zhujiangkou Basin and the Beibuwan Basin,developed high-quality lacustrine source rocks during the Eocene rifting period.These source rocks are vital for hydrocarbon generati...The northern South China Sea,including the Zhujiangkou Basin and the Beibuwan Basin,developed high-quality lacustrine source rocks during the Eocene rifting period.These source rocks are vital for hydrocarbon generation in the northern South China Sea.The ZhuⅠdepression in the Zhujiangkou Basin and the Beibuwan Basin typically exhibit high abundance of C_(30)4-methyl steranes.However,shales in the Eocene Wenchang Formation in the ZhuⅢdepression of the Zhujiangkou Basin contains lower quantities of high-quality lacustrine source rocks with 4-methyl steranes,which often co-elute with some pentacyclic triterpanes in gas chromatography-mass spectrometry(GC-MS).Therefore,the single 4-methylsterane parameter based on GC-MS cannot accurately distinguish organic source in the deep to semi-deep water lacustrine source rocks of the Wenchang Formation from other source rocks,thus impeding the recognition of their contributions to petroleum reservoirs.In this study,GC-MS of aliphatic hydrocarbons,palynofacies and algal identification,as well as stable carbon isotope data of organic matter were used to identify the algal species and construct the paleoclimate during deposition of the Wenchang Formation source rocks in the ZhuⅢdepression of the Zhujiangkou Basin.It is suggested that during the Wenchang Formation period,freshwater green algae prevailed in the lake,which is likely account for the relatively low content of 4-methyl steranes in the high-quality lacustrine source rocks.Controlled by the algal species,it is proposed that the content of C_(30)tetracyclic polyprenoids(TPP)can better indicate the quality of the Wenchang source rocks than C_(30)4-methyl steranes.Consequently,a relationship between the TPP index and the quality of the lacustrine source rocks in the Wenchang Formation of the ZhuⅢdepression was established.A higher TPP index indicates higher organic matter abundance and hydrogen index of the lacustrine source rocks.When applied to the origin analysis of oils in the ZhuⅢdepression,it is believed that the organic-rich deep lacustrine source rocks in the Wenchang Formation made great contribution to the transitional zone crude oils in the Wenchang A and Wenchang B depressions.展开更多
Methylobacterium species,the representative bacteria distributed in phyllosphere region of plants,often synthesize carotenoids to resist harmful UV radiations.Methylobacterium extorquens is known to produce a caroteno...Methylobacterium species,the representative bacteria distributed in phyllosphere region of plants,often synthesize carotenoids to resist harmful UV radiations.Methylobacterium extorquens is known to produce a carotenoid pigment and recent research revealed that this carotenoid has a C_(30) backbone.However,its exact structure remains unknown.In the present study,the carotenoid produced by M.extorquens AM1 was isolated and its structure was determined as 4-[2-O-11Z-octadecenoyl-β-glucopyranosyl]-4,4′-diapolycopenedioc acid(1),a glycosylated C_(30) carotenoid.Furthermore,the genes related to the C_(30)carotenoid synthesis were investigated.Squalene,the precursor of the C_(30) carotenoid,is synthesized by the co-occurrence of META1p1815,META1p1816 and META1p1817.Further overexpression of the genes related to squalene synthesis improved the titer of carotenoid 1.By using gene deletion and gene complementation experiments,the glycosyltransferase META1p3663 and acyltransferase META1p3664 were firstly confirmed to catalyze the tailoring steps from 4,4′-diapolycopene-4,4′-dioic acid to carotenoid 1.In conclusion,the structure and biosynthetic genes of carotenoid 1 produced by M.extorquens AM1 were firstly characterized in this work,which shed lights on engineering M.extorquens AM1 for producing carotenoid 1 in high yield.展开更多
Moldowan first reported the identification of C<sub>30</sub>-steranes. He is of opinion that C<sub>30</sub>-steranes are novel markers for marine petroleum and sedimentary rocks. Subsequently, ...Moldowan first reported the identification of C<sub>30</sub>-steranes. He is of opinion that C<sub>30</sub>-steranes are novel markers for marine petroleum and sedimentary rocks. Subsequently, the same author, in another paper, further suggested that as a reduced product of early diagenesis, the C<sub>30</sub>-steranes may be principally derived from propylidene-cholesterol widespread in marine organisms such as diatom,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The Basic Prospective Research Project of China National Offshore Oil Corporation under contract No.KJQZ-2024-2003.
文摘The northern South China Sea,including the Zhujiangkou Basin and the Beibuwan Basin,developed high-quality lacustrine source rocks during the Eocene rifting period.These source rocks are vital for hydrocarbon generation in the northern South China Sea.The ZhuⅠdepression in the Zhujiangkou Basin and the Beibuwan Basin typically exhibit high abundance of C_(30)4-methyl steranes.However,shales in the Eocene Wenchang Formation in the ZhuⅢdepression of the Zhujiangkou Basin contains lower quantities of high-quality lacustrine source rocks with 4-methyl steranes,which often co-elute with some pentacyclic triterpanes in gas chromatography-mass spectrometry(GC-MS).Therefore,the single 4-methylsterane parameter based on GC-MS cannot accurately distinguish organic source in the deep to semi-deep water lacustrine source rocks of the Wenchang Formation from other source rocks,thus impeding the recognition of their contributions to petroleum reservoirs.In this study,GC-MS of aliphatic hydrocarbons,palynofacies and algal identification,as well as stable carbon isotope data of organic matter were used to identify the algal species and construct the paleoclimate during deposition of the Wenchang Formation source rocks in the ZhuⅢdepression of the Zhujiangkou Basin.It is suggested that during the Wenchang Formation period,freshwater green algae prevailed in the lake,which is likely account for the relatively low content of 4-methyl steranes in the high-quality lacustrine source rocks.Controlled by the algal species,it is proposed that the content of C_(30)tetracyclic polyprenoids(TPP)can better indicate the quality of the Wenchang source rocks than C_(30)4-methyl steranes.Consequently,a relationship between the TPP index and the quality of the lacustrine source rocks in the Wenchang Formation of the ZhuⅢdepression was established.A higher TPP index indicates higher organic matter abundance and hydrogen index of the lacustrine source rocks.When applied to the origin analysis of oils in the ZhuⅢdepression,it is believed that the organic-rich deep lacustrine source rocks in the Wenchang Formation made great contribution to the transitional zone crude oils in the Wenchang A and Wenchang B depressions.
基金the National Key R&D Program of China(grant No.2021YFC2103500)National Natural Science Foundation of China(grant No.22078169)+1 种基金Natural Science Foundation of Shandong Province,China(ZR2021MC074,ZR2020MC008)Shandong Provincial Key Research and Development Plan(2021ZDSYS28).
文摘Methylobacterium species,the representative bacteria distributed in phyllosphere region of plants,often synthesize carotenoids to resist harmful UV radiations.Methylobacterium extorquens is known to produce a carotenoid pigment and recent research revealed that this carotenoid has a C_(30) backbone.However,its exact structure remains unknown.In the present study,the carotenoid produced by M.extorquens AM1 was isolated and its structure was determined as 4-[2-O-11Z-octadecenoyl-β-glucopyranosyl]-4,4′-diapolycopenedioc acid(1),a glycosylated C_(30) carotenoid.Furthermore,the genes related to the C_(30)carotenoid synthesis were investigated.Squalene,the precursor of the C_(30) carotenoid,is synthesized by the co-occurrence of META1p1815,META1p1816 and META1p1817.Further overexpression of the genes related to squalene synthesis improved the titer of carotenoid 1.By using gene deletion and gene complementation experiments,the glycosyltransferase META1p3663 and acyltransferase META1p3664 were firstly confirmed to catalyze the tailoring steps from 4,4′-diapolycopene-4,4′-dioic acid to carotenoid 1.In conclusion,the structure and biosynthetic genes of carotenoid 1 produced by M.extorquens AM1 were firstly characterized in this work,which shed lights on engineering M.extorquens AM1 for producing carotenoid 1 in high yield.
文摘Moldowan first reported the identification of C<sub>30</sub>-steranes. He is of opinion that C<sub>30</sub>-steranes are novel markers for marine petroleum and sedimentary rocks. Subsequently, the same author, in another paper, further suggested that as a reduced product of early diagenesis, the C<sub>30</sub>-steranes may be principally derived from propylidene-cholesterol widespread in marine organisms such as diatom,
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)
