Isolasi dan karakterisasi bakteri asam laktat penghasil bakteriosin dari fermentasi susu jagung

Abstract

Corn milk is one of diversification product in the society as a nutrition source selection than staple food. Corn milk is low durability due to contamination spoilage bacteria. The use of chemical preservatives can be used to keep the spoilage bacteria contamination but these preservatives are very harmfull to humans. The research study purpose is isolation and identification of lactid acid bacteria producing bacteriocin from fermented corn for biopreservatives on corn milk. Isolation of lactid acid bacteria (LAB) from fermented corn was done spontaneously with 3 treatments and 2 replications. The first treatment of the tube was opened and not heated (JMB), the tube was closed and not heated (JMT) and the tube was closed and heated (JMA). Screening LAB performed was used the best flavour as a organoleptic test. The selected LAB as the best organoleptic characteristics, also able to maintain the flavor after 6 months of storage at 40C of temperature. The bacteria was found will be selected by direct antagonism method with stab inoculation againts indicator bacteria strain Staphylococcus aureus and Escherichia coli. The bacteria that produced a clear zone was chosen to next selection by using well diffusion method. The LAB screening results of organoleptic tests and producing antimicrobial compounds then observed of growth phase. The 13 isolates were tested by using well diffusion methods which used S. aureus as microbial test in pH 4, pH 6 after that protease treatments. Consumer acceptance of the BAL inoculation were measured and analyzed using hedonic value based Fredman test. The chosen bacteria was identification by 16S rRNA. Total of 33 isolates were obtained. The first until third treatment obtained 22, 7, and 5 isolates respectively. The selected LAB is a bacteria by the widest clear zone is Lactobacillus JMB 9, Lactobacillus JMB 13 dan Lactobacillus JMT 6. Lactobacillus JMB 4 and Lactobacillus JMB 6 as BAL candidate who can give the best flavor. Direct antagonist screening method obtained 13 isolates that produce inhibitory effects on Sthapylococcus aureus and E.coli. Based on the screening results obtained Lactobacillus JMB 6 has the ability to produce inhibition in pH 6. The addition of protease make a disturb of bacteriocins activity. The antimicrobial substance produced by Lactobacillus JMB 6 can be concluded as a bacteriocins. The addition of bacteriocins treatment and inoculation of lactic acid bacteria showed preference value not significantly different scents. Bacteriocins added and bacterial selected inoculation on corn milk showed that all treatments have the ability to retain flavor. Identification bacterial based on 16 sRNA was showed 97% similarity LAB JMB 4 with Lactobacillus plantarum.