Screening studies on culturable bacteria for degradation of food nutrients and secondary metabolites in the intestinal tract of Paralipsa gularis
Paralipsa gularis(Zeller)(P.gularis)is a serious pest of corn cob found in Yunnan maize production ar-eas in recent years.To clarify the metabolic function of its intestinal culturable bacteria on food nutrients and secondary metabolites,we used the combination method of thylakoid bioassay and high-performance liquid chromatography,to screen and study the degrading bacteria of the larval intestine of P.gularis that can be cultured for starch,cellulose,pro-tein,ferulic acid,vanillin,and p-hydroxybenzoic acid.The results show that 18 bacterial strains are screened from P.gu-laris intestinal culturable bacteria with starch,cellulose,protein,ferulic acid,vanillin,and p-hydroxybenzoic acid degrad-ing power,respectively.Among them,Bacillus subtilis(DH3)has the strongest starch degrading ability,with the ratio of hyaline circle(Hp)and colony diameter(Dp)of 1.70.Bacillus thuringiensis(BS1)has the strongest degradation of cel-lulose,with Hp/Dp of 4.46.Serratia marcescens(BS5)has the strongest protein degradation,with Hp/Dp of 3.46.Ba-cillus.subtilis(DH3)has the strongest degradation of ferulic acid,with a degradation rate of 99.92%.Brucella pseu-dogrignonii(DH5)has the strongest degradation of vanillin,with a degradation rate of 99.82%.Staphylococcus sapro-phyticus(BS2 and BS7),Bacillus stratosphericus(BS4),Serratia marcescens(BS5),Bacillus cereus(BS8),and Bru-cella pseudogrignonensis(DH5)all have a strong ability to degrade p-hydroxybenzoic acid(degradation rates:100%).In summary,the intestinal tract of P.gularis is enriched with bacteria that can degrade maize nutrients and maize second-ary metabolites,and these intestinal bacteria play an important role in the metabolism of nutrients and secondary metabo-lites in P.gularis.The results will provide not only a theoretical basis for the study of the functions of P.gularis intestinal bacteria and the comprehensive control of P.gularis,but also the strain resources for development and utilization of func-tional bacterial strains.