Aldehyde-degradation Function Analysis And Application Evaluation Of Deep-sea Bacterium Halomonas Axialensis ACH-L-8

Aldehydes are widely used in industrial production,although aldehydes could be formed endogenously,some typical aldehydes like formaldehyde and acetaldehyde are cytotoxic and mutagenic compounds to organisms,also a kind of the major environmental pollutants.Many acetaldehyde-degradation strains of deep-sea microbial from the enrichment sample of deep sea water were isolated by my colleague.Acetaldehyde tolerability of Halomonas axialensis strain ACH-L-8 is up to 1.5 g/L,and can grow with acetaldehyde as the sole carbon source,also degrade propionaldehyde and butyraldehyde.In this paper,strain ACH-L-8 has carried on the thorough research,include function analysis of aldehyde degradation,draft genome of strain ACH-L-8,and aldehydes degradation mechanism was analyzed.NADP+-linked aldehyde dehydrogenase?ALDH?was purified and characterized,cells immobilized of strain ACH-L-8 were preliminary studied.The major conclusions are shown below:?1?Strain ACH-L-8 culture in 50 mL basic seawater culture medium with 500 mg/L acetaldehyde,and with 4% inoculum size,while entered logarithmic phase in 32 h,the degradation rate of acetaldehyde reached 85%,the biggest biomass OD600 was 2.5.?2?Draft genome of strain ACH-L-8 was performed,generated to reach a 239-fold depth of coverage.The genome contained 155 scaffolds consist of 183 contigs with a total size of 3,618,231 bp.The genome encoding 3,352 proteins,51 t RNAs and 3 rRNAs.Genome contains 20 ALDH superfamily genes,which 3 genes encoding aldehyde dehydrogenase,to participate in the 14 aldehydes degradation related metabolic pathways,including glycolysis way,amino acid metabolism and fat acid metabolism way and so on.?3?Aldehyde dehydrogenase with 60 kDa molecular weight of Halomonas axialensis ACH-L-8 was purified to homogeneity with electrophoretic grade by steps of ammonium sulfate precipitation,DEAE-Sepharose chromatography and Sephacryl S-200 HR.The enzyme was purified about 241-fold and had a specific activity of 52.44 U/mg,the recovery rates was 5.1%.This aldehyde dehydrogenase got optimally active at 40 °C and pH 7.0,it was stable at temperature below 40°C and showed good stability under pH range of 7.0-8.0.K⁺,Na⁺,Li⁺ and Ca²⁺ was found to slightly enhance the enzymatic activity,while Ni⁺,Mn²⁺ and Zn²⁺ showed inhibition effect in different degrees.This ALDH showed high degradation rate of acetaldehyde,propionaldehyde and butyraldehyde.?4?The strain ACH-L-8 cells were immobilized by sodium alginate embedding method.The degradation rate of acetaldehyde in 24 h of immobilized particles made of 12 h cultivate cells was 73%.The acetaldehyde degradation efficiency of immobilized cell particles of 24 h was significantly higher than that immobilized cell particles of 12 h,with 100% degradation rate in 24 h.Immobilization particles of 12 h cultivate cells place for 15 d,the degradation efficiency of acetaldehyde was 58%,is significantly less than place for 0 d.Strain ACH-L-8 as one source of marine microorganisms,the aldehydes degradation ability is outstanding,has great application potential in the environment pollution treatment of aldehydes.Genome sequencing and the purification of aldehyde dehydrogenase provides a theoretical basis for the specific application of this strain,immobilized study provide a feasible method on treatment of aldehyde pollutants of environment,laid the groundwork for putting this strain into practical application.