An erythromycin-resistant strain of probiotic Lactobacillus paracasei ssp. paracasei LBC-1 (LBC-1e) was added to part-skim Mozzarella cheese in alginate-microencapsulated or free form at a level of 10(8) and 10(7)cfu/g, respectively. Survival of LBC-1e and total lactic acid bacteria (LAB) was investigated through the pasta filata process of cheese making (in which the cheese curd was heated to 55 °C and stretched in 70 °C-hot brine), followed by storage at 4 °C for 6 wk and simulated gastric and intestinal digestion. This included incubation in 0.1 M and 0.01 M HCl, 0.9 M H(3)PO(4), and a simulated intestinal juice consisting of pancreatin and bile salts in a pH 7.4 phosphate buffer. Some reductions were observed in both free and encapsulated LBC-1e during heating and stretching, with encapsulated LBC-1e surviving slightly better. Changes in total LAB losses during heating and stretching did not reach statistical significance. During storage, a decrease was observed in total LAB, but no statistically significant decrease was observed in LBC-1e. Survival during gastric digestion in HCl was dependent on the extent of neutralization of HCl by the cheese, with more survival in the weaker acid, in which pH increased to 4.4 after cheese addition. The alginate microcapsules did not provide any protection against the HCl. It is interesting that survival of the encapsulated LBC-1e was greater during incubation in H(3)PO(4) than in the HCl gastric juices. Proper selection of simulated gastric digestion media is important for predicting the delivery of probiotic bacteria into the human intestinal tract. Neither free nor encapsulated LBC-1e was affected by incubation in the pancreatin-bile solution. Based on the level of probiotic bacteria in cheese needed to provide a health benefit and its survival during simulated gastric digestion, as determined in this study, it should theoretically be possible to lower the amount that needs to be ingested in cheese by up to a factor of 10(3) compared with other fermented dairy foods or when consumed as supplements.

The objective of this study was to determine the effect of encapsulation on survival of probiotic Lactobacillus acidophilus ATCC 4356 (ATCC 4356) in yogurt and during artificial gastric digestion. Strain ATCC 4356 was added to yogurt either encapsulated in calcium alginate or in free form (unencapsulated) at levels of 8.26 and 9.47 log cfu/g, respectively, and the influence of alginate capsules (1.5 to 2.5mm) on the sensorial characteristics of yogurts was investigated. The ATCC 4356 strain was introduced into an artificial gastric solution consisting of 0.08 N HCl (pH 1.5) containing 0.2% NaCl or into artificial bile juice consisting of 1.2% bile salts in de Man, Rogosa, and Sharpe broth to determine the stability of the probiotic bacteria. When incubated for 2h in artificial gastric juice, the free ATCC 4356 did not survive (reduction of >7 log cfu/g). We observed, however, greater survival of encapsulated ATCC 4356, with a reduction of only 3 log cfu/g. Incubation in artificial bile juice (6 h) did not significantly affect the viability of free or encapsulated ATCC 4356. Moreover, statistically significant reductions (~1 log cfu/g) of both free and encapsulated ATCC 4356 were observed during 4-wk refrigerated storage of yogurts. The addition of probiotic cultures in free or alginate-encapsulated form did not significantly affect appearance/color or flavor/odor of the yogurts. However, significant deficiencies were found in body/texture of yogurts containing encapsulated ATCC 4356. We concluded that incorporation of free and encapsulated probiotic bacteria did not substantially change the overall sensory properties of yogurts, and encapsulation in alginate using the extrusion method greatly enhanced the survival of probiotic bacteria against an artificial human gastric digestive system.

A Gram-stain positive, rod-shaped, non-spore-forming Lactobacillus species (WDC04T), which may be associated with late gas production in cheese, was isolated from aged Cheddar cheese following incubation on MRS agar (pH 5.2) at 6°C for 35 d. WDC04T had 97% 16S rRNA sequence identity with Lactobacillus hokkaidonensis, Lactobacillus oligofermentans, Lactobacillus danicus, Lactobacillus suebicus strain CECT5917, and Lactobacillus vaccinostercus. API 50 CH carbohydrate fermentation panels indicated WDC04T could only utilize one of the 50 substrates tested, ribose, although it does slowly utilize galactose. In the API ZYM system, WDC04T was positive for leucine arylamidase, valine arylamidase, cysteine arylamidase (weakly), naphthol-AS-BI-phosphohydrolase, and β-galactosidase. Total genomic DNA was sequenced from Lactobacillus sp. WDC04T using a whole-genome shotgun strategy on a 454 GS Titanium pyrosequencer. The sequence was assembled into a 1.90 Mbp draft genome consisting of 105 contigs with preliminary genome annotation performed using the RAST algorithm (rast.nmpdr.org). Genome analysis confirmed the pentose phosphate pathway for ribose metabolism as well as galactose, n-acetylglucosamine, and glycerol fermentation pathways. Genomic analysis places WDC04T in the obligately heterofermentative group of lactobacilli and metabolic results confirm this conclusion. The result of genome sequencing, along with 16S rRNA analysis, indicates WDC04T represents a new Lactobacillus species, for which the name Lactobacillus wasatchensis sp. nov. is proposed. The type strain is WDC04T (=DSM 29958T=LMG 28678T).

The COVID-19 pandemic caused by a novel coronavirus (SARS-CoV-2) is a serious health concern in the twenty-first century for scientists, health workers, and all humans. The absence of specific biotherapeutics requires new strategies to prevent the spread and prophylaxis of the novel virus and its variants. The SARS-CoV-2 virus shows pathogenesis by entering the host cells via spike protein and Angiotensin-Converting Enzyme 2 receptor protein. Thus, the present study aims to compute the binding energies between a wide range of bacteriocins with receptor-binding domain (RBD) on spike proteins of wild type (WT) and beta variant (lineage B.1.351). Molecular docking analyses were performed to evaluate binding energies. Upon achieving the best bio-peptides with the highest docking scores, further molecular dynamics (MD) simulations were performed to validate the structure and interaction stability. Protein–protein docking of the chosen 22 biopeptides with WT-RBD showed docking scores lower than −7.9 kcal/mol. Pediocin PA-1 and salivaricin P showed the lowest (best) docking scores of − 12 kcal/mol. Pediocin PA-1, salivaricin B, and salivaricin P showed a remarkable increase in the double mutant’s predicted binding affinity with −13.8 kcal/mol, −13.0 kcal/mol, and −12.5 kcal/mol, respectively. Also, a better predicted binding affinity of pediocin PA-1 and salivaricin B against triple mutant was observed compared to the WT. Thus, pediocin PA-1 binds stronger to mutants of the RBD, particularly to double and triple mutants. Salivaricin B showed a better predicted binding affinity towards triple mutant compared to WT, showing that it might be another bacteriocin with potential activity against the SARS-CoV-2 beta variant. Overall, pediocin PA-1, salivaricin P, and salivaricin B are the most promising candidates for inhibiting SARS-CoV-2 (including lineage B.1.351) entrance into the human cells. These bacteriocins derived from lactic acid bacteria hold promising potential for paving an alternative way for treatment and prophylaxis of WT and beta variants.

Lactobacillus wasatchensis sp. nov. has been studied for growth and gas formation in a control Cheddar cheese and in cheese supplemented with 0.5% ribose, 0.5% galactose, or 0.25% ribose plus 0.25% galactose using regular and accelerated cheese ripening temperatures of 6 and 12°C, respectively. Milk was inoculated with (1) Lactococcus lactis starter culture, or (2) Lc. lactis starter culture plus Lb. wasatchensis (10(4) cfu/mL). In the control cheese with no added Lb. wasatchensis, starter numbers decreased from 10(7) initially to ~10(4) cfu/g over 23 wk of ripening at 6°C. When the cheese was ripened at 12°C, or if Lb. wasatchensis was added, the final starter counts were 1 log lower. In contrast, nonstarter lactic acid bacteria in the cheese increased from <10(2) cfu/g at press to 10(6) to 10(7) cfu/g after 23 wk, with higher numbers being observed with ripening at 12°C. In cheese with no added Lb. wasatchensis, levels of Lb. wasatchensis were initially below the enumeration threshold but counts of up to 10(3) cfu/g were detected after 23 wk. When the cheese was inoculated with Lb. wasatchensis, it could be enumerated throughout ripening, with final levels at 23 wk being dependent on whether ribose had been added to the cheese curd. With added ribose (with or without added galactose), Lb. wasatchensis grew to 10(7) to 10(8) cfu/g after 23 wk, whereas without added ribose it was 1 log lower. In all cheeses with added Lb. wasatchensis, greater gas formation was observed at 12°C, with most gas production occurring after ~16 wk. Very little gas production was detected in cheese without added Lb. wasatchensis ripened at 12°C or in cheese with added Lb. wasatchensis ripened at 6°C. Adding a combination of ribose and galactose caused more gas formation, putatively because of the ability of Lb. wasatchensis to co-utilize both sugars and grow to high numbers, and then produce gas from galactose as ribose levels were depleted. Even without sugar supplementation, gas was observed in cheese with added Lb. wasatchensis after 16 wk. We also observed that Lb. wasatchensis could grow to high cell densities when grown in carbohydrate-restricted broth containing lactococcal cell lysate. This suggests that during cheese ripening, lysis of starter bacteria provides sufficient substrates (such as ribose) to allow growth of Lb. wasatchensis and, if fermentable hexose is available, the cheese will become gassy. We conclude that Lb. wasatchensis is a previously undetected contributor to late gas formation in Cheddar cheese and the defect is more pronounced when elevated ripening temperatures are used.

Antibiotic resistance (AR) in lactic acid bacteria (LAB) has become an emerging concern in the probiotic and food industries. LAB, a key component of the human microbiota and widely used in probiotic products, can harbor antibiotic resistance genes (ARGs), which may transfer to pathogenic microorganisms. This review provides an updated overview of AR in LAB, outlining mechanisms of resistance, both intrinsic and acquired, and their implications for probiotics. Recent studies have reported the presence of resistant LAB strains in food products, highlighting the need for stringent monitoring and regulatory measures. Additionally, the review addresses the declining production of new antibiotics, exacerbating the AR crisis. Advances in bioinformatics offer powerful tools for predicting and identifying ARGs in LAB, providing powerful tools to combat this issue. We also discuss strategies to mitigate AR in LAB, such as the use of nanotechnology, combination therapy, bacteriocins, and the potential role of CRISPR and other genome editing tools.