Isolation And Characteristics Of Propanethiol-degrading Strain And The Analysis Of Biodegradation Metabolites

In this paper,a new propanethiol degrading strain,named S-1,was isolated from the activated sludge of a pharmaceutical factory in Zhejiang using culture enrichment technique.It was identified as Pseudomonas putida by Biolog Gen ? MicroPlates with 0.646 of the similarity index at 24h and 16S rDNA gene sequencesimilarity of 98.4%with Pseudomonas putida NBRC 14164T(GenBank:AP013070).S-1 could degrade 2.5 mg/bottle propanethiol completely in 9 h with a biomass yield of 0.36 g dry weight/g propanethiol and the specific growth rate of 0.19 h-1 were obtained,which indicated S-1 had a high degradation activity.Propanethiol degradation by S-1 influenced by environmental factors were investigated,the results showed that the optimum pH and temperature were 7.0 and 30?,respectively.NH4Cl,Mg2+ concentration had less impact on S-1 growth and propanethiol-degrade,and Ca2+ has some toxic effects on S-1 with a high concentration.When the NaCl concentration was less than 0.85%,it had no influence on propanethiol degradation.This strain could grow well in the poor nutritional condition indicating that the strain has a better competitive in the environment.Propanethiol-degrading conditions were optimized based on response surface methodology.It showed that the interactive influence between temperature and NaCl concentration is significant,and the optimized conditions were:temperature 28.2?,pH 7.2,NaCl concentration 0%.Under these conditions,the propanethiol degradation rate was 62.8%at 6h.The induction process was not required in propanethiol degradation from this investigation.S-1 had a wide substrate spectrum,and could utilize most of volatile organic sulfides,alcohols,aldehydes.And S-1 could degrade the complex pollutant effectively.what's more,these characteristics was not only solved the problems of amplification culture of environmental microbiology,but also ensured the stability of biodegradation used in wastewater or exhaust gas treatment.Furthermore,the intermediates of propanethiol-degrading had been detected by GC/MS and HPLC.Dipropyl disulfide,3-hexanal,3-hexanol,2-hexanal,2-hexanol and S0 were the major possible degrading metabolite.Almost 94.2%of sulfate were released,and C02 production rate was up to 56.0%when propanethiol was degraded proving that the loss of propanethiol was mainly via mineralization and incorporation into cell material.The real-time fluorescent quantitative PCR based on TaqMan probe method was established.According to 16S rRNA sequences of strain S-1,the specific primers and probes were designed,amplified fragment,prepared positive standard plasmid and got the best reaction conditions and reaction system.This experiment could provide foundation to further investigation.