Characterization of bacteriocinogenic strains of lactic acid bacteria in fowl and fish intestines and mushroom

The purpose of the current study was to investigate the biogenic amine production of lactic acid bacteria (LAB) strains (Lactobacillus pentosus, Lactobacillus plantarum, Pediococcus acidilactici, Lactobacillus paraplantarum, Lactobacillus fermentum, Lactococcus raffinolactis, Pediococcus pentosaceus and Leuconostoc mesenteroides) which in fermented foodstuff. Biogenic amine production of LAB strains was monitored in histidine decarboxylase broth using HPLC method. Significant differences were observed on ammonia (AMN) and biogenic amines accumulation among LAB strains (p<0.05). Although P. acidilactici produced lesser AMN than other LAB, it was observed that all LAB strains produced high amount of AMN. LAB strains produced all amines in amounts between 1.48 and 1187.50 mg/L. Histamine production by LAB was in range from 17.20 mg/L by P. acidilactici to 126.26 mg/L by Lb. fermentum. The lowest tyramine concentration was observed by P. acidilactici with value of 14.66 mg/L whilst the highest tyramine production was found by L. raffinolactis with value of 64.43 mg/L.

Background: Lactic acid bacteria (LAB) are reported to have immune activating property. The genetically modified LAB strains producing interleukin (IL) -10 were under consideration for the treatment of inflammatory bowel diseases (IBD). Soybean is rich in necessary nutrients, and the fermented soybean products are known for its health benefits. Aims and Objectives: The current study was aimed to screen LAB with the immune activating property, and production and evaluation of LAB mediated fermented soymilk product. Materials and Methods: Screening of LAB from the fermented foods collected in Chiang Mai. To select a potent LAB strain, the LAB isolates were scrutinized for acid tolerant, bile tolerant, growth rate, antimicrobial ability, adhesion property, and induction of IL-10 production. The physical properties of fermented soymilk (FSM) were evaluated, and in vitro activation of IL-10 by FSM was assessed using Caco-2 cell line. Results: About 742 LAB, strains were isolated from 335 fermented food samples. Based on the tested properties, LAB33 was selected as a potent LAB strain, and used for the fermentation of soymilk for 30 days. The LAB33 FSM was superior in quality regarding probiotic nature and microbiological safety. Conclusion: The results of the study suggested that LAB33 is the potent probiotic strain for the production of soymilk-based fermented functional food supplements for the betterment of IBD patients. Further, strain identification is required to register the strain in a public repository, and sustainable utilization for the benefit of mankind.

In this study, lactic acid bacteria (LAB) strains were isolated from fermented grains of traditional Chinese Baijiu, and their probiotic properties were characterized. Eleven out of 29 LAB strains showed good tolerance to the gastrointestinal tract and bile salts. The surface characteristics (auto-aggregation, co-aggregation, hydrophobicity), safety (hemolytic and antibiotic sensitivity), antibacterial activity against three foodborne pathogens, and antioxidant and hypoglycemic properties of the 11 LAB strains were investigated. Principal component analysis (PCA) was used to comprehensively evaluate LAB strains and their probiotic properties. It was found that Weissella cibaria (OP288150), Pediococcus acidilactici (OP288151), Pediococcus pentosaceus (OP288154), Pediococcus pentosaceus (OP288156) and Levilactobacillus brevis (OP288158) showed high probiotic properties, with potential for commercial development. The results also demonstrated that fermented grains of Chinese Baijiu can be used as a source of high-quality probiotics.

Forage preservation for livestock feeding is usually done by drying the plant material and storing it as hay or ensiling it into silage. During the ensiling process, the pH in the system is lowered by the activities of lactic acid-producing bacteria (LAB), inhibiting the growth of spoilage microorganisms and maintaining the quality of the ensiled product. To improve this process, inoculation of LAB could be used as starter cultures to shorten the ensiling time and control the fermentation process. Here, we compared fermentation quality and bacterial dynamics in two plant materials, whole-plant corn (Zea mays L.) and Napier grass (Pennisetum purpureum), with and without starter inoculation. The efficacy of Lactobacillus plantarum, L. brevis, and Pediococcus pentosaceus as starter cultures were also compared in the ensiling system. In whole-plant corn, pH decreased significantly, while lactic acid content increased significantly on Day 3 in both the non-inoculated and LAB-inoculated groups. Prior to ensiling, the predominant LAB bacteria were Weissella, Enterococcus, and Lactococcus, which shifted to Lactobacillus during ensiling of whole-plant corn in both the non-inoculated and LAB inoculated groups. Interestingly, the epiphytic LAB associated with Napier grass were much lower than those of whole-plant corn before ensiling. Consequently, the fermentation quality of Napier grass was improved by the addition of LAB inoculants, especially L. plantarum and a combination of all three selected LAB strains showed better fermentation quality than the non-inoculated control. Therefore, the different abundance and diversity of epiphytic LAB in plant raw materials could be one of the most important factors determining whether LAB starter cultures would be necessary for silage fermentation.

Three beer-spoilage strains of lactic acid bacteria (LAB), Lactobacillus brevis ABBC45, L. lindneri DSM 20690T and L. para-collinoides DSM 15502T, exhibited strong ATP-yielding ability in beer. To investigate energy sources, these beer-spoilage strains were inoculated into beer. After the growth of the strains in beer, utilized components were determined by high performance liquid chromatography (HPLC). As a result, it was shown that citrate, pyruvate, malate and arginine were consumed by beer-spoilage LAB strains examined in this study. The four components induced considerable ATP production even in the presence of hop compounds, accounting for the ATP-yielding ability of the beer-spoilage LAB strains observed in beer. We have further examined the ATP-yielding ability of other strains of bacteria in beer. Beer-spoilage bacteria, including Pectinatus frisingensis and P. cerevisiiphilus, showed strong ATP-yielding abilities, whereas species frequently isolated from brewery environments exhibited low ATP-yielding abilities. Although some of the nonspoilage LAB strains produced substantial amount of ATP in beer, the measurement of ATP-yielding ability was considered to be useful as a rapid pre-screening method for potential beer-spoilage bacteria isolated from brewery environments.

Lactic acid bacteria (LAB) have been isolated from fermented foodstuff and pre-identified using API 50 CHL and confirmed by polymerase chain reaction method to investigate the protective properties against important foodborne pathogens of their cell-free supernatants (CFS) and neutralized cell-free supernatants (NCFS). The antimicrobial activity of CFS and NCFS was determined using agar well diffusion assay. Biogenic amine production of LAB strains were also monitored in tyrosine decarboxylase broth (TDB). The highest and lowest histamine production were obtained by Pediococcus pentosaceus (155.66 mg/L) and Lactobacillus plantarum (5.96 mg/L), respectively. CFS obtained from LAB isolates showed better antimicrobial effects against pathogens than NCFS. The CFS and NCFS obtained from L. plantarum showed a high antimicrobial effect against S. Paratyphi A with inhibition zone diameter 22.5 and 16.5 mm, respectively. The CFS and NCFS of L. raffinolactis showed strong antibacterial activities against Listeria monocytogenes, with zone diameter 23.5 and 24.5 mm. Practical applications Antimicrobial activity of cell-free and neutralized cell-free supernatants obtained from LAB strains was evaluated. Biogenic amine production of LAB strains were also monitored in tyrosine decarboxylase broth. All LAB isolates had the capacity to produce biogenic amines. Cell-free supernatants obtained from LAB isolates showed better antimicrobial effect against pathogens than neutralized cell-free supernatants. Our results showed that cell-free supernatants can be used as a bio-protective agent in the food industry.

Native grasses possess rich diversity and contribute to enhancing the nutritional value of silage, promoting digestion and absorption, thus improving the health of livestock such as cattle and sheep. However, in northern China, the silage fermentation process occurs at relatively low temperatures, necessitating the use of cold-tolerant lactic acid bacteria (LAB). This study examined the effect of Pediococcus acidilactici (L10), a strain selected for its low-temperature tolerance, added to native grass silage at 5°C (LT), 15°C (MT), and room temperature 25°C (CK) for 60 days. The organization of the microbial community and the metabolomic profiles were examined. The results showed that temperature significantly (P < 0.05) influenced the pH, lactic acid (LA) concentration, and LAB populations of the silage after 60 days. The water-soluble carbohydrates (WSC) and crude protein (CP) contents in the LT treatment were significantly higher than those in the CK treatment, and the pH in the LT treatment was significantly lower than in the CK treatment. In terms of the dynamic alterations within the microbial community, Pediococcus acidilactici prevailed in the LT treatment, whereas Lactobacillus plantarum was the major genus in the MT treatment, and the CK treatment was characterized by the dominance of Lactobacillus plantarum and Levilactobacillus brevis. The study also revealed that bacterial behavior and metabolism were influenced by two-component systems and quorum sensing. At 5°C the upregulation of citric acid, salicylic acid, and L-proline was ascribed to the modification of glycolysis and the tricarboxylic acid cycle. Salicylic acid was significantly (P < 0.05) positively correlated with Lactiplantibacillus plantarum, while L-proline had significantly (P < 0.05) positive correlations with Pediococcus acidilactici, Lactococcus lactis, and Weissella confusa. These findings suggest that the addition of isolated Pediococcus acidilactici can enhance the quality of low-temperature native grass silage by regulating microbial metabolic pathways and community composition.IMPORTANCEThis study aimed to screen and identify low-temperature-resistant lactic acid bacteria (LAB) strains from native fermented silage of grassland pastures, evaluating their impact on silage quality in cold conditions. Under natural conditions, LAB on forage grasses are present in low numbers and exhibit insufficient activity, which is further hindered by low temperatures during ensiling, leading to slow fermentation. The findings highlighted the effects of low temperatures on the microbial community, fermentation characteristics, and metabolomic profiles of silage. After anaerobic fermentation, the main LAB strains at different temperatures were Levilactobacillus brevis, Lactiplantibacillus plantarum, and Pediococcus acidilactici, with Pediococcus acidilactici being dominant at 5°C. Temperature significantly affected the pH, lactic acid content, and water-soluble carbohydrates of silage, indicating an interaction between LAB strains and fermentation temperature. The study suggests that adding Pediococcus acidilactici can enhance silage quality by regulating microbial metabolic pathways and composition under low-temperature conditions.

Lactic acid bacteria (LAB) are the most well-documented, “generally regarded as safe” microorganisms used in food fermentation, cosmetics, and pharmaceuticals. Many probiotic strains are utilized for the production of beneficial metabolites, such as bacteriocins and lactic acid, which influence the preservation, organoleptic characteristics, and nutritional properties of food. However, these strains are usually cultured using complex and expensive media, which significantly contribute to the cost of the final product. Thus, this study aims to develop a low-cost alternative medium (LCAM) for the growth and metabolite production of industrially important LAB strains. After several preliminary experiments, an LCAM containing rice bran extract, waste coconut (mature) water, baker’s yeast extract, table sugar, and salts was subjected to a statistically-guided optimization study for growth support of a model LAB strain Lactobacillus plantarum BS. Based on the second-order response mathematical model, the optimized medium composition was 35% rice bran extract and 58% waste coconut water, 1% baker’s yeast extract, 1% table sugar, and 5% salt solution (LCAM A) plus a modified version without baker’s yeast and table sugar (LCAM B). Predicted values were acceptable at 95% (8.91 and 8.88 log CFU/mL) and highly comparable (102% relativity) with the commercial complex medium used as control. Both LCAM formulations were found to support the growth and metabolite production of different LAB genera (L. plantarum BS, Lactococcus lactis NCDO 497, Enterococcus faecalis M4-3, Streptococcus thermophilus BIOTECH 1555, and Pediococcus acidilactici BIOTECH 1068). The LCAM supported the metabolite production of these LAB strains comparable with the commercial medium but is 7.4–7.6-fold cheaper than the cheapest commercial medium. This significant cost reduction has a huge prospect on the large-scale utilization of LAB. Nevertheless, further studies are necessary to enhance the nutritive composition of LCAM for other genera of LAB.

The aim of this study was to isolate lactic acid bacteria (LAB) from sucuk and to determine their antibiotic resistance and biogenic amine production abilities. A total of 65 presumptive LAB were isolated and they were molecularly identified as Pediococcus acidilactici (47.7%), Enterococcus faecium (36.9%), Lactobacillus sakei ssp. carnosus (4.6%), Lactobacillus sakei ssp. sakei (4.6%), Pediococcus pentosaceus (3.1%), Enterococcus faecalis (1.5%) and Weissella viridescens (1.5%) by sequencing 16S rDNA. The LAB were found resistant to clinically relevant antibiotics to cure infections. Sixty‐eight percent of the Enterococcus strains and the other entire LAB displayed resistance from 2 to 8 of the antibiotics tested. All LAB did not decarboxylate histidine, lysine or ornithine. The decarboxylase genes (hdc, ldc and odc) were not detected in LAB. However, 68.0% of the Enterococcus strains decarboxylated tyrosine. The tyrosine decarboxylase gene (tdc) was also detected in these tyraminogenic strains.Practical ApplicationsLactic acid bacteria (LAB) are one of the most important groups of bacteria that are known to be technologically important in the production of dry‐fermented sausages such as sucuk. The present study describes isolation, identification of LAB from sucuk and determines their antibiotic resistance and biogenic amine production abilities. LAB isolated from sucuk samples were found resistant to clinically important antibiotics and most of them have multiple antibiotic resistance patterns. The findings of our study suggest that LAB in sucuk may play a role to spread the antibiotic resistance between other bacteria including pathogens. In addition, most of the Enterococcus strains isolated from sucuk produce tyramine. For these reasons, LAB isolated from sucuk may have a potential risk to consumer health indirectly.

The present study aimed at characterizing lactic acid bacteria (LAB) strains isolated from traditional sourdoughs collected in different regions of Morocco. Isolated strains were firstly identified using Gram staining and catalase reaction test. Presumptive LAB strains were then checked for various phenotypical properties including growth at 45°C, resistance to NaCl, enzyme production, acidification capacity, diacetyl and exopolysaccharide (EPS) production, and antifungal activity. Finally, selected LAB strains were identified using 16S rDNA sequencing. Results showed that 32.1% of the isolates were thermophilic (45°C) and 83.9% were resistant to NaCl (6.5%). Moreover, 51.7 and 37.5% were able to produce diacetyl and EPS, respectively. Regarding enzyme production, 55.3 and 7.1% of the isolates showed lipolytic and proteolytic activities, respectively. Low pH values (3.37-3.76) were obtained after 24h of incubation of LAB strains in de Man, Rogosa and Sharpe (MRS) broth. Antifungal activity test against Aspergillus flavus, Aspergillus niger and Penicillium spp. showed an inhibition rate up to 50%. Bacterial DNA sequencing showed that LAB isolates belong to seven species, chiefly Levilactobacillus brevis, Lentilactobacillus parabuchneri, Lactiplantibacillus plantarum, Pediococcus pentosaceus, Enterococcus hirae, Bifidobacterium pseudocatenulatum, and Companilactobacillus paralimentarius. These findings, for the first time in Moroccan sourdoughs, indicate that the isolated LAB strains have good multifunctional properties and could be suitable as good starters for sourdough bread production under controlled conditions.

Exploring the impact of lactic acid bacteria on the biocontrol of toxigenic Fusarium spp. and their main mycotoxins

Microorganisms cause considerable losses of ensiled animal fodder. Anaerobic deterioration is mediated principally by bacteria but this can be minimised by careful practice during silage making. Aerobic deterioration is however difficult to control, especially when ambient temperatures are high and feeding rates are low as in a mild winter for example. The principal cause of this type of spoilage is the growth of yeast and, to a lesser extent, moulds. The development of strategies to control this would thus be advantageous. Previously we have screened several strains of lactic acid bacteria for production of antifungal compounds without success. In this study, strains of Bacillus were screened for the production of compounds inhibiting growth of yeast. Many species of Bacillus produce antibiotics of which Gramicidin S and Tyrocidine are the best characterised. Antifungal peptides are also known to be produced. The major family of these are lipopeptides which comprise iturins (Delcambe & Devignat, 1957), surfactins (Kluge et al., 1988), bacillomycins (Peypouxet al., 1981) and mycosubtilins (Besson & Michel, 1990). Most of these compounds are cyclic peptides containing a sequence of D and L amino acids closed by a beta-amino acid carrying a long aliphatic chain. They all appear to be active against fungi and yeasts. Although there are numerous lipopeptidic antibiotics produced by B.subtilis strains only few hydrophilic and antifungal metabolites have been reported in the literature, including the dipeptides bacilysin (Walker & Abraham, 1970) and chlorotetain (Rapp et al., 1988). Another similar substance, previously named Rhizoctonia factor (Michener & Snell, 1949), has recently been identified as a hydrophilic phosphono-oligopeptide usually existing as a dipeptide and named rhizocticin (Rapp et al., 1988). Some isolates of B.licheniformis have been found to produce bacilysin (Kugler et al., 1990), but there are no other reports on the production of di- and tri-peptides in this organism.

Wastewater from the production of lactic acid bacteria as feedstock in anaerobic digestion

We investigated the suitability of rice flour for fermented beverage production using various strains of lactic acid bacteria. Fermentation led to a decrease in pH from 5.04&amp;ndash;5.17 to 3.74&amp;ndash;4.35. At the same time, total acidity increased (1.28&amp;ndash;2.59&amp;nbsp;g/l) due to lactic acid (0.59&amp;ndash;2.76 g/l) and acetic acid (0.11&amp;ndash;0.30 g/l) production. Fermentation of rice beverages also caused a gradual decrease in glucose and fructose concentration. Lactic acid bacteria proliferated in the first phases of fermentation, and cell counts reached a maximum after 12 h. The highest growth rate (v&lt;sub&gt;LAB&lt;/sub&gt; = 0.44 Log&lt;sub&gt;10&lt;/sub&gt; CFU/ml/h) was observed in a sample with the culture of Lactobacillus brevis CCM 1815. Viscosity of beverages decreased significantly after 24&amp;nbsp;h of fermentation. The highest values of sensory parameters were observed in a monoculture of Lactobacillus plantarum CCM 7039 and in a sample with a mixed culture of Lactobacillus plantarum CCM 7039 and Bifidobacterium longum CCM 4990.

To investigate the characteristics of different LAB strains isolated from subtropics and their effects on Napier grass (Pennisetum purpureum Schum.) silage with two dry matter (DM) levels, sugar fermentation pattern, and growth profiles of three screened lactic acid bacteria (LAB) strains [Pediococcus pentosaceus (PP04), Weissella cibaria (WC10), and Lactobacillus plantarum (LP694)] were characterized, and then used either individually or in combination at 1.0×106 cfu g-1 fresh weight to inoculate grass having 15% or 25% DM. Treatments were applied: (1) no inoculant (control); (2) PP04; (3) WC10; (4) LP694; (5) M-1 (PP04: WC10=2:1); (6) M-2 (PP04: LP694=1:2); (7) M-3 (WC10: LP694=2:1); (8) M-4 (PP04: WC10: LP694=2:1:1). The results showed that all inoculations increased LAB, DM recovery, and lactic acid (LA) concentration, while decreasing pH, the ammonia nitrogen/total nitrogen (NH3-N/TN), and butyric acid (BA) concentration compared to control group in both DM. However, the effect of inoculations was very limited at 15% DM. Silages with inoculants achieved higher silage quality at 25% DM than 15% DM. The different LAB inoculants result in significant differences in silage quality, while W. cibaria decreased the pH and inhibited the growth of undesirable bacteria and those characteristics were not affected by the DM content.