High throughput screening of technological and biopreservation traits of a large set of wild lactic acid bacteria from Brazilian artisanal cheeses

Effects of a Sorghum Beverage with Lacticaseibacillus paracasei on Body Composition, Lipid Profiles, and Intestinal Health in Overweight and Obese Adults: A Randomized Single-Blind Pilot Study

(1) Background: This study aimed to evaluate the effect of an extruded whole-grain sorghum beverage containing L. paracasei on body composition, lipid profiles, and intestinal health in overweight and obese adults. (2) Methods: A chronic, single-blind randomized controlled pilot study was conducted with 30 volunteers allocated to three groups (n = 10/group): extruded sorghum beverage (ESB), extruded sorghum beverage with L. paracasei (ESPB), and control beverage (CB) (waxy maize starch). The chemical composition of the beverages was analyzed. Volunteers consumed the beverages for ten weeks at breakfast, along with individual dietary prescriptions. Body composition, biochemical markers, gastrointestinal symptoms, stool consistency, intestinal permeability, short-chain fatty acids, fecal pH, and stool L. paracasei DNA concentration were analyzed at the beginning and end of the intervention period. (3) Results: The ESB showed better composition than the CB, particularly in terms of resistant starch content, total phenolic compounds, condensed tannins, and antioxidant capacity. Both the ESB and the ESPB had an effect on body composition (estimated total visceral fat and waist volume), biochemical markers (Castelli index I), and intestinal health (Bristol scale, diarrhea score, valeric acid, and L. paracasei DNA concentration). No changes were observed in the CB group after the intervention. (4) Conclusions: Whole-grain sorghum beverages demonstrated good nutritional value, and consumption of these beverages, with or without L. paracasei, provided health benefits, including improvements in body composition, Castelli index I scores, and intestinal health, in overweight and obese adults.

Risk factor-based clustering of Listeria monocytogenes in food processing environments using principal component analysis

Listeria monocytogenes has a range of strategies that allow it to persist as biofilms in food processing environments (FPE), making it a pathogen of concern to the food industry. The properties of these biofilms are highly variable among strains, and this significantly affects the risk of food contamination. The present study therefore aims to conduct a proof-of-concept study to cluster strains of L. monocytogenes by risk potential using principal component analysis, a multivariate approach. A set of 22 strains, isolated from food processing environments, were typed by serogrouping and pulsed-field gel electrophoresis, showing a relatively high diversity. They were characterized in terms of several biofilm properties that might pose a potential risk of food contamination. The properties studied were tolerance to benzalkonium chloride (BAC), the structural parameters of biofilms (biomass, surface area, maximum and average thickness, surface to biovolume ratio and roughness coefficient) measured by confocal laser scanning microscopy and (3) transfer of biofilm cells to smoked salmon. The PCA correlation circle revealed that the tolerance of biofilms to BAC was positively correlated with roughness, but negatively with biomass parameters. On the contrary, cell transfers were not related to three-dimensional structural parameters, which suggests the role of other variables yet unexplored. Additionally, hierarchical clustering grouped strains into three different clusters. One of them included the strains with high tolerance to BAC and roughness. Another one consisted of strains with enhanced transfer ability, whereas the third cluster contained those that stood out for the thickness of biofilms. The present study represents a novel and effective way to classify L. monocytogenes strains according to biofilm properties that condition the potential risk of reaching the consumer through food contamination. It would thus allow the selection of strains representative of different worst-case scenarios for future studies in support of QMRA and decision-making analysis.

Lactic Bacteria in Artisanal Cheese: Characterization through Metagenomics

Artisanal cheese, produced with raw milk by a predominantly manual approach, has a historical and cultural tradition related to the region of origin. Given its economic and cultural importance, the main objective of this study was to investigate and characterize the diversity of lactic acid bacteria (LAB) of artisanal cheeses produced and traded by family agro-industries in a region of southern Brazil. The LAB composition of artisanal cheese samples, belonging to different municipalities of the Region of Vale do Taquari, were characterized by the next-generation sequencing (NGS) method, amplifying the V3/V4 region of the 16S rRNA gene. A total of 35 LAB species, distributed in seven genera, were identified, and rarefaction analysis suggested that the total diversity assessed by 16S rRNA analysis was high in the analyzed samples. The average Ph ranged from 4.6 to 6.6, and a correlation with the genus Lactococcus (r = 0.62) was the most expressive. The LAB genera identified in the cheese samples were Bavariicococcus, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Marinillactibacillus, and Pediococcus. Lactococcus lactis was the most predominant species, present in all samples. Although some species have been identified in the three altitudes studied, the abundance varied according to geographic environments. Enterococcus italicus is more present at high altitudes, unlike Lactococcus plantarum and Lactococcus raffinolactis at low altitudes. Lactococcus lactis was present in the three geographic environments evaluated, but the highest abundance was observed at high altitudes. The identification of LAB present in fermented cheeses is essential to understand the organoleptic quality during the maturation process as well as to establish the shelf life, including the safety and the overall quality of the cheese. This specific microbiota contributes to the flavor and unique characteristics of the regional dairy products, and on the other hand can be a source of specific starter cultures that guarantee the product’s identity.

In Vitro Probiotic Characterization and Safety Assessment of Lactic Acid Bacteria Isolated from Raw Milk of Japanese-Saanen Goat (Capra hircus)

Two novel probiotic strains of lactic acid bacteria were successfully isolated from the raw milk of dairy Japanese-Saanen goats. Selection criteria for positive candidates were grown on de Man-Rogosa-Sharpe or M17 selective medium at 30, 35, or 42 °C anaerobically, and characterized based on Gram reaction, catalase test, and tolerance to low pH and bile salts. Among the 101 isolated positive candidates, two strains, YM2-1 and YM2-3, were selected and identified as Lacticaseibacillus rhamnosus using 16S rDNA sequence similarity. Culture supernatants of the two strains exhibited antipathogenic activity against Salmonella enterica subsp. enterica serovar. Typhimurium, Shigella sonnei, methicillin-resistant Staphylococcus aureus, methicillin-sensitive Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli O157. The antipathogenic activities were retained to some extent after neutralization, indicating the presence of antipathogenic substances other than organic acids in the culture supernatants. The two strains were sensitive with coincidental minimum inhibition concentrations (indicated in the parentheses hereafter) to ampicillin (0.25 μg/mL), chloramphenicol (4 μg/mL), gentamycin (4 μg/mL), kanamycin (64 μg/mL), streptomycin (16 μg/mL), and tetracycline (4 μg/mL). Furthermore, the two strains were resistant to clindamycin (16 μg/mL) and erythromycin (4 μg/mL). In addition, both YM2-1 and YM2-3 strains showed less unfavorable activities, including bile acid bioconversion, carcinogenic-related enzymes, mucin degradation, plasminogen activation, and hemolysis, than the detection limits of in vitro evaluation methods used in this study. In summary, L. rhamnosus YM2-1 and YM2-3 are highly safe and promising probiotic strains applicable in the dairy industry, and were first isolated from the raw milk of Japanese-Saanen goats.

Application of Cheese Whey Containing Postbiotics of Lactobacillus acidophilus LA5 and Bifidobacterium animalis BB12 as a Preserving Liquid in High-Moisture Mozzarella

High-moisture mozzarella cheese (HMMC) is a highly perishable cheese with a short shelf life. In this study, the effects of UF cheese whey containing postbiotics from Lactobacillus acidophilus LA-5 (P-LA-5), Bifidobacterium animalis BB-12 (P-BB-12), and their combination on the microbial (i.e., psychrophiles, mesophiles, lactic acid bacteria, and mold-yeast population) and sensory properties of HMMC were investigated. Postbiotics were prepared in a cheese whey model medium as a novel growth media and used as a preserving liquid in HMMC. The results demonstrate that postbiotics reduced the growth of all microorganisms (1.5-2 log CFU/g reduction) and P-LA5 and P-BB12 had the highest antibacterial performance on mesophiles and psychrophiles, respectively. Mold and yeast had the highest susceptibility to the postbiotics. Postbiotics showed a significant effect on maintaining the microbial quality of HMMC during storage, proposing postbiotics as a new preserving liquid for HMMC.