Screening and Identification of Lactic Acid Bacteria with Antimicrobial Activity to Aquatic Products Spoilage Bacteria from Marine Wetland

Lactic acid bacteria(LAB)strains with strong antagonistic activity to Shewanella putrefaciens,Pseudomonas aeruginosa,Vibrio parahaemolyticus were isolated from roots of plants in Jinzhou Bohai coast wetland to develop a biological preparation for the preservation of seafood. LAB with antibacterial activity was isolated from Suaeda glauca roots using the Oxford cup method. The formation process of antibacterial substance was analyzed by growth curve. The antimicrobial activity of cell-free supernatant(CFS)produced by LAB was analyzed from the stability of pH,protease,temperature and NaCl concentration. Strain JP-12 with strong inhibitory activity was obtained from roots of Suaeda glauca,and its antagonistic activity mainly existed in CFS. The growth curve analysis showed that the maximum activity of strain JP-12 was reached after 28 h of incubation. Antibacterial activity of CFS decreased treated by different proteases. And the most sensitive to pepsin,the loss rate of activity was 24.21%. The antagonistic activity of CFS was remained after treatment with 40~121 ℃ for 30 min and kept stable within pH3.0~4.5.CFS possessed strong antibacterial activity at the concentration of NaCl in 3.0% and 3.5%,and its diameter of inhibition zone reached 18.46,18.15 mm,respectively. The strain JP-12 was identified as Lactobacillus plantarum by physiological and biochemical characteristics and 16S rRNA gene sequencing. This study provided a new approach to excavate resource of antagonistic LAB and its application in aquatic products preservation.