Optimization of Bacterial Concentrate Media for Lactobacillus Sakei

Two strains of lactic acid bacteria were selected for the study (Lactobacillus sakei Lsk-45andLactobacillus sakeiDSM 20017). Bacterial media, based on rice and rice flour, were tested as an alternative to media based on whey. A comparison of the different types of media showed that there was better growth of the selected strains on themedium based on rice flour.Statistical analyses, including factorial experiments and response surface analyses, were used to optimizethe composition of the bacterial medium for Lactobacillus sakei propagation. Bacteriological peptone and rice flour were found to be good growth factors for Lactobacillus sakei.For Lactobacillus sakei Lsk-45,better growth was obtained with the use of 7.75-10 g/L of peptone and 57.5-75 g/L of rice flour. For Lactobacillus sakei DSM 20017, better growth was obtained with the use of 7-10 g/L of peptone and 40-75 g/L of rice flour. Keywords: starters, media, Lactobacillus sakei, fermentation,fish products, bacterial strains, lactic acid bacteria

Development of Active Packaging Based on Agar-Agar Incorporated with Bacteriocin of Lactobacillus sakei

In the search for new biodegradable materials and greater microbiological safety and stability of perishable food products, this study aimed to develop a bioplastic antibacterial film incorporating bacteriocin for application in commercial curd cheese and monitoring of microbiological stability. Films with good handling characteristics as well as physical, barrier, and mechanical properties were obtained. Regarding the antibacterial activity, the microbial reduction was demonstrated in a food matrix, obtaining a reduction of 3 logarithmic cycles for the group of coagulase positive staphylococci and from 1100 to <3.00 MPN/g in the analysis of thermotolerant coliforms. Therefore, the film presented food barrier characteristics with the external environment and adequate migration of the antibacterial compound to the product, contributing to the reduction of contamination of a food with high initial microbial load.

The study of biotechnological potential of Lactobacillus sakei LSK-103

Lactic acid bacteria play an important role in the production of food. Bacterial cultures widely used in the food industry often have a set of characteristics that ensure the stability of the production. The biotechnological properties of Lactobacillus sakei LSK-103 have been studied in the present work. Lactobacillus sakei LSK-103 has shown high biochemical activity on MRS medium. It has been found that after 16 h of cultivation at the end of the exponential growth phase, the number of viable bacterial cells reaches 10 CFU/cm. The study of the effect of different concentrations of sodium chloride on biomass accumulation has shown that Lactobacillus sakei LSK-103 is highly resistant to salt. Increase in NaCl concentration from 2 to 10 % leads to decrease in cell survival from 96.8 to 91.2 %, and in number of bacteria to 10 CFU/cm. Morphological studies indicate that an increase in the concentration of sodium chloride in the medium is accompanied by cell cohesion, the formation of cell conglomerates. Cohesion intensifies intercellular contacts and increases the resistance of Lactobacillus sakei LSK-103 to osmotic stress. The high survival rate of Lactobacillus sakei LSK-103 has been shown in the presence of bile, phenol (0.4 %), high (pH 8.3) and low (pH 3.5) values of active acidity of the medium indicating its probiotic properties. The results of research have shown that the Lactobacillus sakei LSK-103 has high biotechnological potential and can be used as part of bacterial preparations for the production of fermented fish products.