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Schematic representation of common acid-resistance mechanisms in microorganisms, shown with examples. (A) Gad system; gadA/B encode glutamate decarboxylase GadA/B, which convert Glu to GABA, and GadC (encoded by gadC), which acts as the Glu/GABA antiporter. (B) Biofilm and cell density; comCDE and luxS are involved in a quorum-sensing system that is essential for biofilm formation, and the las system is necessary for the exogenous Pseudomonoas quinolone-signaling molecule to stimulate biofilm formation. (C) F 1 -F 0 -ATPase; as a proton pump, this complex pumps H + out to increase intracellular pH. (D) Protection of macromolecules; RecA and AP endonuclease are involved in DNA repair, DnaK is a protein repair chaperone, and IrrE is a global regulatory protein that can stimulate recA transcription. (E) Alkali production; urea is transformed into NH 3 by urease to neutralize protons. The Adi and Agd systems can also produce NH 3 through several reactions. Glu = glutamate; Adc = arginine decarboxylase; Agd = agmatine deiminase; Ptc = putative putrescine transcarbamylase; Adi = arginine deiminase; Otc = ornithine transcarbamylase; Ck = carbamate kinase. The figure is reprinted from Liu et al. (2015) with permission from Elsevier.
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The selection of potential probiotic strains that possess the physiological capacity of performing successfully in the gastrointestinal tract (GIT) is a critical challenge. Probiotic microorganisms must tolerate the deleterious effects of various stresses to survive passage and function in the human GIT. Adhesion to the intestinal mucosa is also an...
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Abundant microbiota resides in the organs of the body, which utilize the nutrition and form a reciprocal relationship with the host. The composition of these microbiota changes under different pathological conditions, particularly in response to stress and digestive diseases, making the microbial composition and health of the hosts body interdepend...
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... was found in a single copy of all the examined L. mucosae strains. Bile salt hydrolase is one major mechanism of detoxification of bile salts by their deconjugation [75] which leads to a protective effect against toxic conjugated bile acids during intestinal transit. The presence of BSH is considered to be one of the features of probiotics [76]. ...
Probiotics are crucial components for maintaining a healthy gut microbiota in pigs, especially during the weaning period. Lactic acid bacteria (LAB) derived from the gastrointestinal tract of wild boars can serve as an abundant source of beneficial probiotic strains with suitable properties for use in pig husbandry. In this study, we analyzed and characterized 15 strains of Limosilactobacillus mucosae obtained from the gut contents of wild boars to assess their safety and suitability as probiotic candidates. The strains were compared using pan-genomic analysis with 49 L. mucosae strains obtained from the NCBI database. All isolated strains demonstrated their safety by showing an absence of transferrable antimicrobial resistance genes and hemolysin activity. Based on the presence of beneficial genes, five candidates with probiotic properties were selected and subjected to phenotypic profiling. These five selected isolates exhibited the ability to survive conditions mimicking passage through the host’s digestive tract, such as low pH and the presence of bile salts. Furthermore, five selected strains demonstrated the presence of corresponding carbohydrate-active enzymes and the ability to utilize various carbohydrate substrates. These strains can enhance the digestibility of oligosaccharide or polysaccharide substrates found in food or feed, specifically resistant starch, α-galactosides, cellobiose, gentiobiose, and arabinoxylans. Based on the results obtained, the L. mucosae isolates tested in this study appear to be promising candidates for use as probiotics in pigs.
... The fermented sardine was reported to have biological activities of preventive hyperglycemia in vitro [13]. These biopeptides can offer many advantages compared with traditional synthetic molecular drugs because of the wide spectrum of therapeutic effects, low toxicity, and structural diversity [14]. Although lactic acid bacteria (Lactobacillus species) are currently used to ferment hydrolyzed proteins of various animal and plant proteins (such as seeds, beef meet, and fish), while few reports involved the structural characterization and the effect of fermented hydrolysate protection on ethanol-induced gastric ulcer. ...
In this study, the oyster hydrolysates, unfermented hydrolysate with goat milk/milk protein, and fermented oyster hydrolysates (fortified with goat milk/milk protein) were prepared to explore the quality and gastroprotection of different fermented hydrolysates. The content of Lys, Leu, and Val increased after fermentation with goat milk protein (OYF-GP) addition, while unsaturated fatty acids (UFAs) exhibited a downward trend. “Grass,” “acidic,” “milky,” “fishy,” and “metallic” were identified as the key sensory attributes. Forty-two volatiles were totally identified by gas chromatography–mass spectrometry in different fermented oyster hydrolysates. 4-Hexen-1-ol, hexanoic acid, 2-pentenyl-furan, and acetic acid contributed for the aroma profile of OYF-GP. Moreover, OYF-GP possesses potential gastric ulcer prevention activity, which could alleviate oxidative stress and reduce the expression of pro-inflammatory cytokines (TNF-α, IL-β, and NF-κB protein). The research demonstrates the relation of quality and bioactivities in fermented oyster hydrolysates and provides a reference for the intensive processing of oyster industry.
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... Any microorganism to be claimed as a probiotic strain should fulfil the following criteria: "(i) sufficiently characterized; safe for the intended use; (iii) supported by at least one positive human clinical trial conducted according to generally accepted scientific standards or as per recommendations and provisions of local/national authorities when applicable; and (iv) alive in the product at an efficacious dose throughout shelf life'' [9]. As defined by Binda et al. [9], the claimed probiotic organism should be "sufficiently characterized", which includes the confirmation of identifying molecular tools followed by standard tests for probiotic attributes such as survival in low acid and resistance to bile, tolerance to digestive enzymes, adhesion to intestinal wall, antimicrobial activity, anti-carcinogenic activity, cholesterol-reducing effects, stimulation of the immune system, conservation of mucosal stability, antioxidant, auto-aggregation and production of vitamins [10,11]. Probiotics are essentially non-pathogenic microorganisms which confer health beneficial properties to the host, and they are commonly reported from the LAB group such as those belonging to the genus Lactobacillus, Bifidobacterium, Lactococcus and Enterococcus [12]. ...
Consumption of naturally fermented milk (NFM) products is the dietary culture in India. The mountainous people of Arunachal Pradesh in India prepare the assorted artisanal home-made NFM products from cow and yak milk. Previously, we isolated and identified 76 strains of lactic acid bacteria (LAB) from NFM products of Arunachal Pradesh, viz. mar, chhurpi and churkam. We hypothesized that some of these LAB strains may possess probiotic potentials; hence, we investigated the probiotic potentials of these strains. On the basis of in vitro and genetic screening for probiotic attributes including haemolytic ability, 20 LAB strains were selected out of 76 strains, for further analysis. Using in silico analysis, viz. multivariate heatmap and PCA (principal component analysis) biplot, Levilactobacillus brevis AcCh91 was selected as the most promising probiotic strain, which was further characterized by the whole-genome analysis. Lev. brevis AcCh91 showed the highest survival rate of 93.38% in low pH and 86.68 ± 2.69% in low bile and the highest hydrophobicity average of 86.34 ± 5.53%. This strain also showed auto-aggregation and co-aggregation with antimicrobial properties against the pathogens, showed ability to produce beta-galactosidase and cholesterol reduction property and, most importantly, produced GABA, an important psychobiotic element. Genomic analysis of Lev. brevis AcCh91 showed the presence of genes corresponding to GABA, vitamins, amino acids, cholesterol reduction, immunomodulation, bioactive peptides and antioxidant activity. The absence of antimicrobial-resistant genes and virulence factors was observed. Hence, genome analysis supports the probiotic potentials of Lev. brevis AcCh91, which may be further investigated to understand its health-promoting properties.
