Bioprospecção de Lactobacillus spp. em Queijos Minas Artesanais: um estudo de diversidade genética e propriedades tecnológicas

Abstract

Lactic acid bacteria are mainly responsible for the formation of various sensory aspects of artisanal cheeses, also acting as bioprotectors by inhibiting the growth of unwanted microorganisms. The bioprospection of these bacteria makes it possible to find new strains that are different from the existing commercial ones and adapted to the environmental conditions and specific production characteristics of each location. In this study, autochthonous lactic acid bacteria were isolated from Artisanal Minas Cheeses, forming a genetic resource bank for future technological uses. For the first time, cheese samples from all producing regions were analyzed, including, in an unprecedented way, those from Serras de Ibitipoca region. From five cheese samples from each region, 191 lactic acid bacteria were isolated using MRS and M17 culture media. Of this total, 83 Lactobacillus spp. were identified, and 64 distinct fingerprints were found using the Rep-PCR method. Cluster analyzis showed a great genetic diversity in this population of Lactobacillus spp. and the existence of a specific microbiota for each producing region, reinforcing the high discriminatory power of the Rep-PCR technique for the identification of genetically unrelated strains, including those from different samples. The use of both MRS and M17 media improved the identification of genetically unrelated strains. Six strains could be cultured in both media, but ten genetically distinct Lactobacillus spp. were isolated exclusively from M17. Five Lactobacillus strains can potencially be used as adjunct cultures (CAN687, SER797, SAL815, CER844 and SAL933), according to some technological properties. All five isolates were able to produce EPS, highlighting the isolate SAL933 with highest EPS production from lactose. Only three isolates showed proteolytic capacity and none were able to perform lipolysis. All tested isolates antagonized Listeria monocytogenes ATCC7644, but only isolate SER797 showed the production of a protein-based antimicrobial compund. There are several possibilities for using these bacteria in the food and biopolymer industry, but further studies are necessary to characterize these microorganisms, and proper assess their safety and potential applications.