Studies On Isolation, Identification And Characterization Of A Bacteria Strain With High Efficiency To Degrade Linear Alkylbenzene Sulfonates

A bacterial strain, designated as S1, which could utilize Linear AlkylbenzeneSulfonates（LAS） as sole carbon and energy for growth, was isolated fromWangxiaoying sewage. A preliminary research was done on the strain S1includingmorphology, physiology, biochemical characteristics and phylogenetic position. StrainS1was a straight-rod gram negative bacterium, colony diameter2-4mm, edge smooth,colony opaque milk-white, tastes of earth. Physiological and biochemicalcharacteristics were as following: starch hydrolysis test, gelatin hydrolysis test, glucosefermentation tests, VP test, citric acid salt test, indoles test, urea hydrolysis test,produce ammonia test, catalase test and motility test reactions being positive; methylred test, oxidase test and nitrate reducing test being negative. In order to identify thebacteria phylogenetic position16S rRNA molecular identification was done. PCRamplification got a1.5kb gene fragment. The part16S rRNA sequences weredetermined, analyzed and the phylogenetic tree was built according to the homology of16S rRNA sequences. Sequences analysis revealed that strain S1exhibited98.5%similarity to Ochrobactrum anthropi （AM114409）, and the isolated strain S1wasidentified as Ochrobactrum anthropi according to the above molecuar biology,morphological, physiological and biochemical identification results,.The optimum growth conditions of S1strain were pH7.0,30℃and80-100ml/250mL, respectively. The influence of different metallic ion on the growth ofstrain S1were remarkable. Ca²⁺, Na⁺and Mn²⁺promoted the growth of S1；Cu²⁺andFe²⁺slowed the growth of S1；K⁺and Mg²⁺did not have obvious function. The optimalconditions for the growth of strain S1were100ml medium in250ml flask, pH7.0andpeptone0.5g/L. The influence of various factors that affected the growth of S1were astemperature> nitrogen source> the aeration.Strain S1could degradate more than80%of LAS when LAS concentration waslower than1000mg/L, and could still grow when the concentration of LAS reached upto3500mg/L.The supernatant of the growth medium of S1strain had no degradation activity,but the cell disruption degraded LAS. So the enzymes degrading LAS was lacatedinside the bacterium cells.No plasmid was detected by the alkali pyrolysis method, but a plasmid greaterthan20kb was found by Kado method and Agarose electrophoresis. The gelatin degradation test showed that strain S1could use various aromaticcompounds.