Isolation Identification And Characteristics Of Salt-Resistant Lactic Acid Bacteria In Jinzhou Pickled Cucumber

Lactic acid bacteria (LAB) have an important influence on aroma and textureof pickled vegetable products. The excellent LAB strains were screened fromJinzhou pickled cucumber and various fermentant properies of strains werestudied. The main results were as follows:1. The20LAB strains were isolated from all41strains of8pickledcucumber samples, and6salt-resistant strains were screened using salt-resistanttest. Strain L3and L4were identified as Enterococcus sp. and strain L5, L7, L15,L16were identified as Lactobacillus sp. using physiological and biochemicaltests.2. A variety of properties for6LAB strains were studied, such as acid-producing abilitis, antibacterial effects, antioxidant activities, and aroma-productions. The results showed that all strains had diverse acid-producingabilities and the ability of strain L7(the percent of acidproduction1.03%, pH5.54)was the highest of6strains. Different inhibitory effects were exhibited againstEscherichia coli, Salmonella typhi, Staphylococcus aureus, and Penicillum spp.,and strong inhibitions of L7, L15, and L5were displayed against Gram-negative,Gram-positive bacteria and Penicillium, respectively. The results of the scavengehydroxyl radical experiments (13.38-38.56%) revealed that all strains hadscavenging capacities and the scavenging effects of L3, L4, L7were above30%;the results of1,1-diphenyl-2-picryl-hydrazyl free radical scavenging tests showedthat the supernatants of all strains differently had scavenging activities(14.35-40.29%), especially of L16(40.29%). It was found that the supernatants ofstrains mainly played antioxidant role in scavenging effects; the results of ferric(Fe＋3) reducing antioxidant powers (FRAP) assaies revealed that all strainsdistinctly had FRAP, and that of the supernatants for L3(OD value1.591) waseffective and powerful, followed by lower FRAP of L7; the results of superoxideanion scavenging assaies (9.55-36.65%) also abserved that the supernatants of all strains presented the scavenging activities and that of L7(36.65%) was effective.Through analysing two indexs of ethylal and diacetyl (2.70-5.79μg/mL,0.02-3.65μg/mL, respectively) producted by all strains during fermentation, a highlever was displayed on the measured values of L16and L7(ethylal5.79μg/mL,diacetyl3.65μg/mL, respectively) among these.3. Acidproduction of strain L7was optimized with L39(3) orthogonal test,results indicated that lactose was the best carbon source and soya peptone was thebest nitrogen source, the percent of acidproduction for L7was increased to1.60%,and there was a significant increase (16.78%) in acid-producting properties.The salt-resistant LAB strains with excellent fermenting properties werescreened from the Jinzhou pickls, to have some value in theory and application forimproving product quality.