Screening And Characterization On Apocynum Venetum L. Degumming Strains

As a kind of wild bast fiber,the studies of bio-degumming on Apocynum venetum L are very important for the effective utilization of renewable resources and environmental protection.And the isolation and identification of strain for Apocynum venetum L degumming,optimization of strain growth and degumming condition,preliminary analyses of pectinase and optimization of pectinase production were studied in this paper.The main results of research were as follows:1.The two strains having a higher yield of alkaline pectinase were isolated from Apocynum venetum L epidermis,they possesed different phenotypic characterization.Based on the traditional and molecular biology identification,the two strains（named S-1 and S-3） were confirmed as Bacillus subtilis and Acinetobacter junii.As degumming strain, Acinetobacter junii hasn’t been repored.Their 16S rDNA were registered in GenBank,the accession number were FM208849 and FM208850 respectively.2.The strain growth culture medium and condition were also optimized,Bacillus subtilis S-1 can grow well in the medium contain:glucose 15g/L,beef extract 15g/L,NaCl 2g/L,pH is 8.0,culured at 37℃.Meanwhile,for Acinetobacter junii S-3,the condition would be soluble starch 10g/L,beef extract 20g/L,NaCl 2g/L,pH 7.0,temperature is 32℃.3.The preliminary analyses for the pectinase of Bacillus subtilis S-1 indicated that its optional reactive temperature is 40℃,its optional reactive pH is 9.5,and its molecular weight is 39.3kD.4.Based on the different temperature for strain growth and enzymic catalytic reaction, the process of bio-degumming for Bacillus subtilis S-1 can be divided into two parts.The degumming conditions were optimized as follows:the amount of K₂HPO₄ was 0.8%,the bath ratio was 1:25,the inoculation amount was 0.5%;with these conditions,degumming was in progress at 37℃for 18h,and then at 45℃for another 0.5h.The lowest residual gum content can achieve at 10.84%,which was decreased by 4.95%in comparison with the method without heating.5.The producing pectase culture medium of Bacillus subtilis S-1 were optimized as follows:pectin 1g/L,glucose 3g/L,beef extract 10g/L,NaCl 2g/L,pH is 10,the best fermentation time is 24h.All the research above could provide theoretical basis to industrial production for the selection of carbon source.