RESUMO
Lactic acid bacteria (LAB) are pivotal in shaping the technological, sensory, and safety aspects of dairy products. The evaluation of proteolytic activity, citrate utilization, milk pH reduction, and the production of organic compounds, acetoin, and diacetyl by cheese associated LAB strains was carried out, followed by Principal Component Analysis (PCA). Citrate utilization was observed in all Leuconostoc (Le.) mesenteroides, Le. citreum, Lactococcus (Lc.) lactis, Lc. garvieae, and Limosilactobacillus (Lm.) fermentum strains, and in some Lacticaseibacillus (Lact.) casei strains. Most strains exhibited proteolytic activity, reduced pH, and generated organic compounds. Multivariate PCA revealed Le. mesenteroides as a prolific producer of acetic, lactic, formic, and pyruvic acids and acetoin at 30 °C. Enterococcus sp. was distinguished from Lact. casei based on acetic, formic, and pyruvic acid production, while Lact. casei primarily produced lactic acid at 37 °C. At 42 °C, Lactobacillus (L.) helveticus and some L. delbrueckii subsp. bulgaricus strains excelled in acetoin production, whereas L. delbrueckii subsp. bulgaricus and Streptococcus (S.) thermophilus strains primarily produced lactic acid. Lm. fermentum stood out with its production of acetic, formic, and pyruvic acids. Overall, cheese-associated LAB strains exhibited diverse metabolic capabilities which contribute to desirable aroma, flavor, and safety of dairy products.
RESUMO
The biodiversity and succession of lactic acid bacteria (LAB) involved in the production and storage of Brazilian buffalo mozzarella cheese were evaluated. The isolates were characterized by Gram staining and catalase test, by the ability to grow at different conditions: temperatures, pH, concentrations of NaCl, and production of CO2 from glucose. The biodiversity and succession of 152 LAB isolated during cheese production were evaluated by 16S rRNA gene sequencing, Random Amplified Polymorphic DNA (RAPD-PCR), and Restriction Fragment Length Polymorphism (RFLP-PCR) techniques. Most of the strains grow well at 30 °C and are tolerant to 6.5% of NaCl, and in general, the best pH for growing was 9.6. Leuconostoc mesenteroides, Lacticaseibacillus casei, Limosilactobacillus fermentum, and Enterococcus sp. were prevalent and present in almost all steps of production. The LAB strains are typically found in the traditional Italian cheese, except the Leuconostoc citreum species. Sixty clusters were obtained by RAPD-PCR with 85% of similarity (114 isolates) while most of the LAB was clustered with 100% of similarity by the RFLP-PCR technique. The applied techniques enabled a valuable elucidation of the LAB biodiversity and succession, contributing to a better understanding of the specific microbial cultures with a technological aptitude of this cheese.