The effect of wild lactic acid bacteria on the production of goat’s milk soft cheese

Effect of Essential Oils and Dried Herbs on the Shelf Life of Fresh Goat Lump Cheese

In recent years, the use of natural preservatives in food products has gained significant attention due to their potential health benefits and effectiveness. A standardized microbiological analysis was conducted on Slovak farm-produced lump goat cheese samples to determine the antibacterial activity of dry herbs and essential oils added to vacuum-packed goat cheese. We employed five dried herbs and five essential oils derived from the same plants. The microbiological quality of 145 fresh and vacuum-packed goat cheese samples was assessed. The number of coliform bacteria, total viable count, lactic acid bacteria, and microscopic filamentous fungi were examined in raw cheese samples stored for 12 days at 4 °C. All cheese samples were vacuum-packed (control samples were packed without vacuum). This study evaluated the potential benefits of using essential oils and dried herbs from thyme (Thymus serpyllum L.), black pepper (Piper nigrum L.), clove (Eugenia caryophyllus Thunb.), mint (Mentha × piperita L.), and basil (Ocimum basilicum L.) as preservatives. The essential oils were obtained from Hanus Ltd., Nitra, Slovakia, and were applied at a concentration of 2%. The dried herbs were obtained from Popradský čaj (Poprad, Slovakia) and Mäspoma Ltd. (Zvolen, Slovakia). The results showed that all microorganism groups were significantly reduced in cheese samples following the application of essential oils throughout the entire storage period. During the preservation of cheese samples in polyethylene bags used for vacuum packing food, Lactococcus garvieae, L. lactis, Enterobacter cloacae, and Serratia liquefaciens were the most frequently isolated microbiota. Essential oils and dried herbs demonstrated antimicrobial potential during the storage of vacuum-packed goat cheese.

Probiotic Lactic Acid Bacteria from Goat’s Milk Potential Producer of Bacteriocin: Evidence from Liquid Chromatography-Mass Spectrometry

The diverse microbial populations in milk produce a range of antimicrobial compounds that confer preservative action. Goat milk characterized by high nutritional value, medicinal properties and hypoallergenic in nature, constitutes the most prevalent non-bovine milk consumed globally. Lactic acid bacteria (LAB), renowned for their probiotic properties, are important constituents of goat milk microflora. In this study, bacterial strains with probiotic potential were isolated and characterized from milk samples of indigenous Indian goat breeds. On MRS medium, Gram-positive rods were observed after anaerobic culture. Based on 16s rRNA technique LAB from goat milk were identified to belong to Enterococcus durans and Lactobacuillus plantarum. Antimicrobial activities were observed against known pathogens (Staphylococcus aureus, Klebsiella pneumoniae, Escherichia. coli and Salmonella typhimurium) and minimum inhibitory concentration was found to be low (6.5 mg/ml) for most of the isolates. High resistance to both acidic condition (pH 2.0) and 0.3% bile salts was observed along with marginal increase in cell counts in some isolates. Adherence to Caco-2 cell lines was observed in all the four identified LABs and was higher in case of Enterococcus durans compared to Lactobacillus plantarum. LC-MS analysis revealed the presence of lacticin as one of the key component of cell free extracts (CFE) of selected isolate. Goat milk as a source of possible LAB probiotics opens up a whole new avenue of probiotics from non-bovine milk sources. LAB strains isolated in this study are potential probiotic candidates that can be employed as antimicrobial agents in food and pharmaceutical industries.

Use of Calcium Amino Acid Chelate in the Production of Acid-Curd Goat Cheese

Amino acid chelates are a new group of compounds approved for food enrichment, however there is no previous research using calcium amino acid chelate to enrich goat's milk products. The purpose of this research was to evaluate the possibility of using calcium amino acid chelate to produce goat's acid-curd cheese. In this study, four types of acid-curd cheeses from goat's milk subjected to 85 °C/5 min treatment were produced: control cheeses-made from milk without calcium addition and cheeses from milk enriched with 30, 35 and 40 mg of Ca (in 100 g of milk) in the form of calcium amino acid chelate. Goat cheese with calcium amino acid chelate had a higher moisture content, and a lower fat content. More fat was separated with the whey. In cheeses made from the milk with calcium amino acid chelate there was no goaty taste. Enrichment with 35 mg of Ca in 100 g of goat milk increased the calcium content in cheese by 60.5% in comparison to the control sample. However, the enrichment of goat milk with 40 mg Ca (in 100 g of processed milk) increased the calcium content in cheese by only 63.29%.

Synergistic antibacterial and anti-biofilm activity of nisin like bacteriocin with curcumin and cinnamaldehyde against ESBL and MBL producing clinical strains

Bacteriocins are small peptides that can inhibit the growth of a diverse range of microbes. There is a need to identify bacteriocins that are effective against biofilms of resistant clinical strains. The present study focussed on the efficacy of purified nisin like bacteriocin-GAM217 against extended spectrum β-lactamase (ESBL) and metallo-beta-lactamase (MBL) producing clinical strains. Bacteriocin-GAM217 when combined with curcumin and cinnamaldehyde, synergistically enhanced antibacterial activity against planktonic and biofilm cultures of Staphylococcus epidermidis and Escherichia coli. Bacteriocin-GAM217 and phytochemical combinations inhibited biofilm formation by >80%, and disrupted the biofilm for selected ESBL and MBL producing clinical strains. The anti-adhesion assay showed that these combinatorial compounds significantly lowered the attachment of bacteria to Vero cells and that they elicited membrane permeability and rapid killing as viewed by confocal microscopy. This study demonstrates that bacteriocin-GAM217 in combination with phytochemicals can be a potential anti-biofilm agent and thus has potential for biomedical applications.

Encapsulation of Lactobacillus spp. using bovine and buffalo cheese whey and their application in orange juice

The aim of this study was to evaluate and compare the efficiency of bovine (CW) and buffalo cheese whey (BCW) as encapsulating agents for the spray-drying (SD) of endogenous Lactobacillus pentosus ML 82 and the reference strain Lactobacillus plantarum ATCC 8014. Their protective features were also tested for resistance to storage (90 days, 25 °C), simulated gastrointestinal tract (GIT) conditions, and for their application in orange juice. Survival rates after SD were approximately 95% in all samples tested, meaning both CW and BCW performed satisfactorily. After 90 days of storage, both species remained above 7 log Colony Forming Units (CFU)/g. However, CW generally enabled higher bacterial viability throughout this period. CW microcapsule characteristics were also more stable, which is indicated by the fact that BCW had higher moist content. Under GIT conditions, encapsulated lactobacilli had higher survival rates than free cells regardless of encapsulating agent. Even so, results indicate that CW and BCW perform better under gastric conditions than intestinal conditions. Regarding their use in orange juice, coating materials were probably dissolved due to low pH, and both free and encapsulated bacteria had similar survival rates. Overall, CW and BCW are suitable encapsulating agents for lactic acid bacteria, as they provided protection during storage and against harmful GIT conditions.

Comparative Genomics of Lactobacillus acidipiscis ACA-DC 1533 Isolated From Traditional Greek Kopanisti Cheese Against Species Within the Lactobacillus salivarius Clade

Lactobacillus acidipiscis belongs to the Lactobacillus salivarius clade and it is found in a variety of fermented foods. Strain ACA-DC 1533 was isolated from traditional Greek Kopanisti cheese and among the available L. acidipiscis genomes it is the only one with a fully sequenced chromosome. L. acidipiscis strains exhibited a high degree of conservation at the genome level. Investigation of the distribution of prophages and Clustered Regularly Interspaced Short Palindromic Repeats (CRISPRs) among the three strains suggests the potential existence of lineages within the species. Based on the presence/absence patterns of these genomic traits, strain ACA-DC 1533 seems to be more related to strain JCM 10692^T than strain KCTC 13900. Interestingly, strains ACA-DC 1533 and JCM 10692^T which lack CRISPRs, carry two similar prophages. In contrast, strain KCTC 13900 seems to have acquired immunity to these prophages according to the sequences of spacers in its CRISPRs. Nonetheless, strain KCTC 13900 has a prophage that is absent from strains ACA-DC 1533 and JCM 10692^T. Furthermore, comparative genomic analysis was performed among L. acidipiscis ACA-DC 1533, L. salivarius UCC118 and Lactobacillus ruminis ATCC 27782. The chromosomes of the three species lack long-range synteny. Important differences were also determined in the number of glycobiome related proteins, proteolytic enzymes, transporters, insertion sequences and regulatory proteins. Moreover, no obvious genomic traits supporting a probiotic potential of L. acidipiscis ACA-DC 1533 were detected when compared to the probiotic L. salivarius UCC118. However, the existence of more than one glycine-betaine transporter within the genome of ACA-DC 1533 may explain the ability of L. acidipiscis to grow in fermented foods containing high salt concentrations. Finally, in silico analysis of the L. acidipiscis ACA-DC 1533 genome revealed pathways that could underpin the production of major volatile compounds during the catabolism of amino acids that may contribute to the typical piquant flavors of Kopanisti cheese.

Antagonistic lactic acid bacteria isolated from goat milk and identification of a novel nisin variant Lactococcus lactis

Background

The raw goat milk microbiota is considered a good source of novel bacteriocinogenic lactic acid bacteria (LAB) strains that can be exploited as an alternative for use as biopreservatives in foods. The constant demand for such alternative tools justifies studies that investigate the antimicrobial potential of such strains.

Results

The obtained data identified a predominance of Lactococcus and Enterococcus strains in raw goat milk microbiota with antimicrobial activity against Listeria monocytogenes ATCC 7644. Enzymatic assays confirmed the bacteriocinogenic nature of the antimicrobial substances produced by the isolated strains, and PCR reactions detected a variety of bacteriocin-related genes in their genomes. Rep-PCR identified broad genetic variability among the Enterococcus isolates, and close relations between the Lactococcus strains. The sequencing of PCR products from nis-positive Lactococcus allowed the identification of a predicted nisin variant not previously described and possessing a wide inhibitory spectrum.

Conclusions

Raw goat milk was confirmed as a good source of novel bacteriocinogenic LAB strains, having identified Lactococcus isolates possessing variations in their genomes that suggest the production of a nisin variant not yet described and with potential for use as biopreservatives in food due to its broad spectrum of action.