Gene specific primers and DNA probe were designed based on the sequence of 18S rDNA cloned from the red tide alga Thalassiosira rotula. A real-time fluorescent quantitative PCR （RFQ - PCR） method was developed for q...Gene specific primers and DNA probe were designed based on the sequence of 18S rDNA cloned from the red tide alga Thalassiosira rotula. A real-time fluorescent quantitative PCR （RFQ - PCR） method was developed for quantitative detection of T. rotula. The RFQ - PCR assay data showed that the results obtained with the RFQ - PCR quite good agreement with those with the light microscope （LM） counting method, which suggested that the RFQ - PCR could be a useful method for red tide alga detection.展开更多
Carbon, nitrogen, phosphorus, silicon composition of cultured two different sized phytoplankton common species of Thalazsiosira rotula and Skeletonema costatum from the Jiaozhou Bay were measured. Carbon, nitrogen, ph...Carbon, nitrogen, phosphorus, silicon composition of cultured two different sized phytoplankton common species of Thalazsiosira rotula and Skeletonema costatum from the Jiaozhou Bay were measured. Carbon, nitrogen, phosphorus, silicon contents in cell were obvious higher in T. rotula than in S. costatum, but the percents of nitrogen, phosphorus, sihcon contents in cell dry mass in T. rotula were lower than those in S. costatum. The dry mass concentrations of nitrogen,phosphorus, silicon in S. costatum were much higher than those in T. rotula, particularly silicon, the former was 6. 4 times of the latter, showing that S. costatum could more assimilate these elements. Especially, S. costatum had competitive dominance for assimilating silicon, which is beneficial to its becoming a major dominant species in relative short silicon of the Jiaozhou Bay. There were some differences in numerical value of nutrient ratios both laboratory-cultured phytoplankton and different sized suspended particulates （ mainly phytoplankton） in the Jiaozhou Bay, which was caused by the changes of environment. High contents of carbon, nitrogon and relative low phosporus, sil- icon, high molar ratio of nitrogen to phosphorus （far higher than Redfield value） and low ratio of silicon to phosphorus and silicon to nitrogen （far lower than Redfield values） in the two diatoms and different sized suspended particulates were consistent with those in the seawater. Relative short silicon in the seawater and phytoplankton showed that silicon was possibly affectting phytoplankton growth in the Jiaozhou Bay.展开更多
Objective:To evaluate the anti-bacterial and anti-biofilm activity of ethyl acetate fraction of Rotula aquatica Lour.(EFRA)against clinically isolated uropathogenic Escherichia coli.Methods:In vitro antibacterial and ...Objective:To evaluate the anti-bacterial and anti-biofilm activity of ethyl acetate fraction of Rotula aquatica Lour.(EFRA)against clinically isolated uropathogenic Escherichia coli.Methods:In vitro antibacterial and anti-biofilm studies were employed.The antimicrobial activity of EFRA was assayed by the well diffusion method.The minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)of the active fraction were determined by Resazurin method.The time-kill kinetic assay,acridine orange-ethidium bromide staining,propidium iodide uptake assay,and scanning electron microscopic(SEM)analysis were done to evaluate the efficacy of EFRA in killing uropathogenic Escherichia coli.The anti-biofilm activity was determined by 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2 H-tetrazolium-bromide(MTT)assay and specific biofilm formation assay.Results:The well diffusion assay of EFRA showed a very clear zone of inhibition against Escherichia coli BRL-17.The MIC and MBC of EFRA were 2.5 mg/m L and 5 mg/m L,respectively.The time-kill kinetic assay,fluorescence microscopic analysis,propidium iodide uptake assay,and SEM analysis displayed the effect of EFRA in killing the bacteria.The MTT assay and specific biofilm formation assay showed that EFRA prevented the formation of biofilms.Conclusions:The results of the present study confirm that EFRA could prevent bacterial growth and inhibit its biofilm formation.展开更多
Musk macrolides are a kind of rare flavors structurally featuring 14-16 membered rings in the flavour and fragrance industry.While various chemical synthesis routes for musk macrolides exist,there is a growing interes...Musk macrolides are a kind of rare flavors structurally featuring 14-16 membered rings in the flavour and fragrance industry.While various chemical synthesis routes for musk macrolides exist,there is a growing interest in biocatalytic approaches.In this study,a new biocatalytic approach is proposed for the synthesis of musk macrolides from fatty acids using unspecific peroxygenases(UPOs)in combination with lipase.Specifically,the UPO from Marasmius rotula(MroUPO)was utilized as an oxidation catalyst together with the choline oxidase from Arthrobacter nicotinate(AnChOx)for the in situ generation of H_(2)O_(2).The enzymatic cascade process involved the hydroxylation of fatty acids using MroUPO as a catalyst to prepare terminal hydroxylated fatty acids.Under the optimized conditions,14-hydroxy tetradecanoic acid,15-hydroxy pentadecanoic acid and 16-hydroxy hexadecanoic acid were obtained at concentrations of 11.1,18.2 and17.1 mg/L in a 50-mL reaction system,respectively.These hydroxylated fatty acids were then separated and esterified by lipase Novozymes 435 to produce the desired macrolides.Variousω-hydroxy fatty acids were successfully converted into macrolides,with the concentrations of cyclotetradecanolide,cyclopentadecanolide and cyclohexadecanolide reaching 11,29 and 23 mg/L,respectively,in a 10-mL reaction system.This new biocatalytic approach represents a promising method for synthesizing valuable natural flavour compounds.展开更多
基金The research was supported by the National Natural Science Foundation of China under contract No.40406028the National High Technology Research and Development Program of China under contract No.2001AA635090.
文摘Gene specific primers and DNA probe were designed based on the sequence of 18S rDNA cloned from the red tide alga Thalassiosira rotula. A real-time fluorescent quantitative PCR （RFQ - PCR） method was developed for quantitative detection of T. rotula. The RFQ - PCR assay data showed that the results obtained with the RFQ - PCR quite good agreement with those with the light microscope （LM） counting method, which suggested that the RFQ - PCR could be a useful method for red tide alga detection.
基金The National Natural Science Foundation of China under contract No.40776043the Research Foundation of Chinese Ecosystem Re-search Network(Jiaozhou Bay)the Chinese Academy of Sciences under contract No.KZCX3-SW-214
文摘Carbon, nitrogen, phosphorus, silicon composition of cultured two different sized phytoplankton common species of Thalazsiosira rotula and Skeletonema costatum from the Jiaozhou Bay were measured. Carbon, nitrogen, phosphorus, silicon contents in cell were obvious higher in T. rotula than in S. costatum, but the percents of nitrogen, phosphorus, sihcon contents in cell dry mass in T. rotula were lower than those in S. costatum. The dry mass concentrations of nitrogen,phosphorus, silicon in S. costatum were much higher than those in T. rotula, particularly silicon, the former was 6. 4 times of the latter, showing that S. costatum could more assimilate these elements. Especially, S. costatum had competitive dominance for assimilating silicon, which is beneficial to its becoming a major dominant species in relative short silicon of the Jiaozhou Bay. There were some differences in numerical value of nutrient ratios both laboratory-cultured phytoplankton and different sized suspended particulates （ mainly phytoplankton） in the Jiaozhou Bay, which was caused by the changes of environment. High contents of carbon, nitrogon and relative low phosporus, sil- icon, high molar ratio of nitrogen to phosphorus （far higher than Redfield value） and low ratio of silicon to phosphorus and silicon to nitrogen （far lower than Redfield values） in the two diatoms and different sized suspended particulates were consistent with those in the seawater. Relative short silicon in the seawater and phytoplankton showed that silicon was possibly affectting phytoplankton growth in the Jiaozhou Bay.
基金financial assistance in the form of JRF(to A.Vysakh),from CSIR,Government of India 09/499(0093)/2017-EMR-I
文摘Objective:To evaluate the anti-bacterial and anti-biofilm activity of ethyl acetate fraction of Rotula aquatica Lour.(EFRA)against clinically isolated uropathogenic Escherichia coli.Methods:In vitro antibacterial and anti-biofilm studies were employed.The antimicrobial activity of EFRA was assayed by the well diffusion method.The minimum inhibitory concentration(MIC)and minimum bactericidal concentration(MBC)of the active fraction were determined by Resazurin method.The time-kill kinetic assay,acridine orange-ethidium bromide staining,propidium iodide uptake assay,and scanning electron microscopic(SEM)analysis were done to evaluate the efficacy of EFRA in killing uropathogenic Escherichia coli.The anti-biofilm activity was determined by 3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2 H-tetrazolium-bromide(MTT)assay and specific biofilm formation assay.Results:The well diffusion assay of EFRA showed a very clear zone of inhibition against Escherichia coli BRL-17.The MIC and MBC of EFRA were 2.5 mg/m L and 5 mg/m L,respectively.The time-kill kinetic assay,fluorescence microscopic analysis,propidium iodide uptake assay,and SEM analysis displayed the effect of EFRA in killing the bacteria.The MTT assay and specific biofilm formation assay showed that EFRA prevented the formation of biofilms.Conclusions:The results of the present study confirm that EFRA could prevent bacterial growth and inhibit its biofilm formation.
基金supported by the Key Realm R&D Program of Guangdong Province(2022B0202050003)National Natural Science Foundation of China(31930084,32001633)。
文摘Musk macrolides are a kind of rare flavors structurally featuring 14-16 membered rings in the flavour and fragrance industry.While various chemical synthesis routes for musk macrolides exist,there is a growing interest in biocatalytic approaches.In this study,a new biocatalytic approach is proposed for the synthesis of musk macrolides from fatty acids using unspecific peroxygenases(UPOs)in combination with lipase.Specifically,the UPO from Marasmius rotula(MroUPO)was utilized as an oxidation catalyst together with the choline oxidase from Arthrobacter nicotinate(AnChOx)for the in situ generation of H_(2)O_(2).The enzymatic cascade process involved the hydroxylation of fatty acids using MroUPO as a catalyst to prepare terminal hydroxylated fatty acids.Under the optimized conditions,14-hydroxy tetradecanoic acid,15-hydroxy pentadecanoic acid and 16-hydroxy hexadecanoic acid were obtained at concentrations of 11.1,18.2 and17.1 mg/L in a 50-mL reaction system,respectively.These hydroxylated fatty acids were then separated and esterified by lipase Novozymes 435 to produce the desired macrolides.Variousω-hydroxy fatty acids were successfully converted into macrolides,with the concentrations of cyclotetradecanolide,cyclopentadecanolide and cyclohexadecanolide reaching 11,29 and 23 mg/L,respectively,in a 10-mL reaction system.This new biocatalytic approach represents a promising method for synthesizing valuable natural flavour compounds.
