There has been mounting interest in the health benefits associated with live microorganisms commonly known as probiotics. Many probiotic bacterial species have been identified. However, the potential of yeasts as a source of probiotics has not been well explored. The present study was carried out to screen and identify potential probiotic yeasts from selected dairy sources available in Sri Lanka. Yeasts from raw bovine milk and curd were isolated, purified, selected and phenotypically characterized by performing morphological, physiological and biochemical tests. Isolates were assessed for their ability to survive under simulated gastro-intestinal conditions to explore their probiotic potential. Approximately, 190 colonies similar to yeast were isolated and 45 isolates of the division Ascomycota were selected and coded for convenience (SLDY_001-SLDY_045). Most promising probiotic isolates (20) were genotypically identified to be species of Pichia (55%), Candida (30%), and Kluyveromyces (15%) of the family: Saccharomycetaceae. Considering a threshold of >95% similarity to the type strain, eight different yeast species were identified. Isolates (SLDY_005, SLDY_006 and SLDY_039) of Kluyveromyces marxianus species showed the highest probiotic potential from the pool. The strain confirmation and in-vitro/invivo safety assessment of these isolates will further verify their suitability as probiotic starter cultures to be used in local food and pharmaceutical industries.

No abstract

Purpose: Goat's milk is enriched with many nutrients and diverse lactic acid bacteria (LAB). This research was aimed at isolating and characterizing industrially beneficial probiotic lactic acid bacteria present in goat milk and to investigate their ability to produce lactic acid.Research Method: A total of 100 bacterial isolates were obtained from 20 fresh goat's milk samples from Western and North Western provinces in Sri Lanka. These isolates were characterized based on their colony and cell morphologies, physiological and biochemical characteristics, tolerance to in-vitro gastro intestinal tract (GIT) conditions and industrial properties. Species level identification of the isolates was performed based on the obtained phenotypic properties according to the Bergey's manual of systematic bacteriology. Findings:The selected eight probiotic LAB isolates did not produce hemolytic enzymes, therefore, could primarily consider as safe for live consumption. According to the phenotypic properties, the isolates were of Lactobacillus pentosus, Lactobacillus plantarum, Streptococcus thermophilus, Streptococcus bovis, Lactococcus lactis and Enterococcus faecium species. They were able to coagulate skimmed milk which was indicated by the decrease of final pH (4.8-5.9), tolerate to high (45 o C) and low (15 o C) temperatures, grow in different NaCl concentrations (2%, 4%, and 6.5%) and different pH levels (1.5-3.9). HPLC analysis revealed that, Lactobacillus pentosus (33 mg/L) and Streptococcus thermophiles (14mg/L) possessed the highest lactic acid production abilities. Research Limitations:The species level identification of the isolates should be continued employing genotypic methods. The safety of the isolates for live consumption should confirm with in-vivo methods.Originality/Value: The raw goat milk microbiota is considered as a good source of novel lactic acid bacteria (LAB) strains that can be exploited for use as industrial starters and probiotics. Lactic acid produced by the microorganisms; specifically, lactic acid bacteria is an important commodity chemical having many numbers of applications. However, very less research work has been done on the characterization of beneficial lactic acid bacteria present in goat milk produced in Sri Lanka.

Lactic acid bacteria (LAB) are organisms beneficial to the human beings as probiotics which the organism can remain viable under stress conditions in the gastrointestinal tract.The aim of this study was to characterize and evaluate probiotic properties, and antibiotic resistance of thirteen isolates of lactic acid bacteria obtained from curd. In order to characterize the lactic acid bacteria isolates from curd; Gram's staining, endospore staining, motility, catalase reaction, indole production, methyl red test, Voges-Proskauer test, citrate utilization, oxidase activity, urease activity, H2S production, arginine hydrolysis, growth at different temperatures, gas production from glucose and fermentation pattern of different carbohydrates were performed. In order to screen the probiotic potential of the isolates; tolerance to pH, bile, and phenol, survival in the presence of simulated gastric and pancreatic juices were examined. Antibiotic resistance of selected isolates was evaluated using 12 antibiotics. Results of biochemical tests and physiochemical tests revealed that all thirteen isolates (