Screening of high phenyllactic acid producing strain and optimization of soybean meal fermentation process
Using kimchi as raw material,Staphylococcus aureus and Escherichia coli as indicator bacteria,strains with antibacterial effect and high yield of phenyllactic acid were isolated from sauerkraut and primary screened by the calcium dissolution ring method and Oxford cup method and secondary screened by determing phenyllactic acid yield.The strains were applied to fermented soybean meal to evaluate their phenyllactic acid pro-duction performance,and the strains were identified by morphological observation,physiological and biochemical experiments and molecular biolog-ical identification.The results showed that a total of 8 strains with antibacterial effect were obtained,among which the strain R69 had the highest yield of phenyllactic acid(1.25 mg/ml).When phenylpyruvate acid was added,the yield of phenyllactic acid of solid fermented soybean meal was 425.70 mg/kg.The strain R69 was identified as Lactobacillus plantarum.The yield of phenyllactic acid could reach 624.49 mg/kg by using strain R69 for solid fermentation of soybean meal,with protease addition 0.2％,molasses 3％and phenylpyruvate 0.15％,and the growth of E.coli and mold was inhibited effectively.
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