Screening,identification and enzymatic characterization of a marine glucose oxidase strain

Abstract:

[Background] There are abundant undeveloped microbial germplasm resources in the ocean,and the enzymes produced by marine microorganisms have attracted attention because of their tolerance to low temperature,high pressure,and high salt,which are different from those produced by terrestrial microorganisms.[Objective] To isolate and screen out the strains producing glucose oxidase (GOD) from the mud samples of the Bohai Sea,and to study its enzymatic properties.[Methods] The GOD-producing strain was preliminarily screened with plate culture method and re-screened based on enzyme activity.The candidate was identified based on morphological,physiological,and phylogenetic characteristics.The enzymatic properties of the GOD produced by the strain screened out were further characterized in detail.[Results] strain No.31 that produced GOD was screened out and initially identified as Basidiomycete sp.based on morphological and phylogenetic characteristics.The GOD produced by strain No.31 had high activity reaching 20 U/mL at 25–35℃.This enzyme had the optimum reaction temperature at 30℃ and still had activity at 0℃.Its activity was stable between pH 5.0 and 7.0 and peaked at pH 7.0.Ni²⁺,Na⁺,Zn²⁺,Mg²⁺ can improve GOD activity,and high concentrations of Ni²⁺,Na⁺,and Zn²⁺ had significant effect.Different concentrations of β-mercaptoethanol,urea,EDTA,Triton-100,sodium hyposulfite,and DTT had significant inhibitory effect on GOD activity.[Conclusion]The experimental results prove that strain No.31 is a valuable strain producing GOD tolerant to low temperature,which provide a good strain resource for the production of GOD,accumulate relevant data for follow-up research,and fill the blank of using this fungus to produce GOD.

Key words:marine microorganisms;glucose oxidase;screening