In this study, the probiotic potential of five bacteriocin-producing lactic acid bacteria (LAB) strains, isolated from meat products, was investigated. They were presumptively identified as Lactococcus lactis subsp. cremoris CTC 204 and CTC 483, L. lactis subsp. hordinae CTC 484, and Lactobacillus plantarum CTC 368 and CTC 469 according to morphological, biochemical, and physiological characteristics. Analysis of genetic variability (random amplified polymorphic (RAPD)-PCR) and whole-cell proteins (SDS-PAGE) revealed similarity between Lactobacillus strains and variability among Lactococcus strains. The evaluation of the probiotic potential showed that the five LAB strains were tolerant to pH 2.0, and only strain CTC 469 was tolerant to the lowest concentration of the bile salts evaluated (0.1%). All strains showed survival or growth ability at 4, 25, and 37 °C, and tolerance at - 20 °C. Although strain CTC 204 in TSB Broth supplemented with MgSO showed the highest intensity of biofilm production, this compound was produced by all of them. The safety assessment showed that no thermonuclease, hemolytic, or gelatinase activities were detected. All strains were resistant to erythromycin and sensitive to amoxicillin and phenoxymethylpenicillin; furthermore, CTC 204 was resistant to chloramphenicol, CTC 368 and CTC 469 to chloramphenicol and vancomycin, CTC 483 to tetracycline and vancomycin, and CTC 484 to clindamycin and chloramphenicol. The evaluated strains showed biogenic amine production; the lowest levels were produced by CTC 204 and CTC 368 strains. It was concluded that CTC 204 and CTC 368 strains have the greatest potential for becoming probiotics.
Biotechnology has been an essential tool in the search for solutions and in the optimization of bioprocesses associated with issues of human, plant, animal, energy and also the balance of ecosystems on planet Earth. The objective of this research was to present an unconventional substrate (cellulose), in abundance on the planet, to be used as a substitute source of carbon and energy for biotechnology processes, with the possibility of increasing industrial production of biomass and energy. As basis for the research, an extensive literature review and quantitative and qualitative analyzes were carried out. Genetic Engineering techniques were used to enable the yeast Saccharomyces cerevisiae for partial cellulose degradation, through the use of genetic transformation methods to insert a plasmid carrying the cellobiohydrolase cDNA. It was found that the recombinant and biologically active cellobiohydrolase protein was expressed and excreted in haploid and diploid laboratory yeast strains. The analyzes allowed the visualization of cellulolysis halos around colonies of recombinant strains grown in solid YPD medium with 1% microgranular cellulose. The recombinant clones derived from the haploid lineage yielded in average of 1.70 mg ART/mL, while recombinant clones derived from the diploid lineage produced in average of 2.05 mg ART/mL.
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