Probiotic characterisation of lactic acid bacteria isolated from pickles and their potential application as presumptive probiotic starter culture in cucumber pickles

Abstract

This study aimed to isolate lactic acid bacteria (LAB) from traditional pickles, analyse their probiotic properties, identify them and evaluate their potential use in the production of cucumber pickles. The majority of the isolates (65) demonstrated survival at pH 3.0, while only three isolates exhibited this ability at pH 2.0. All isolates were resistant to 0.3% and 1% bile salts and survived at 1.5% (v/v) NaCl. However, the majority of isolates exhibited survival at 10% (v/v) NaCl (73 isolates), phenol (0.4%) (64 isolates), and pepsin (81 isolates) and pancreatin presence (78 isolates). The majority of the isolates demonstrated susceptibility to antibiotics and exhibited antimicrobial activities. Furthermore, some isolates demonstrated limited proteolytic and β-galactosidase activities, with the limited proteolytic activity being particularly beneficial for contributing to positive sensorial properties in this study. Following the evaluation of the probiotic test results, selected isolates were identified as Lactiplantibacillus plantarum, Lactiplantibacillus pentosus, Levilactobacillus brevis, Lentilactobacillus parabuchneri and Pediococcus parvulus based on 16S rRNA sequence analysis. Cucumber pickles were then produced with presumptive probiotics (L. brevis T7, L. parabuchneri T10, L. plantarum T12, and P. parvulus T13) in both single and mixed cell forms, fermented for 15 days and stored at 4 °C for 5 weeks. The results demonstrated that cucumber pickles contained > 6 log CFU/g of presumptive probiotics at the end of fermentation. Sensory analysis results showed that cucumber pickles enriched with presumptive probiotics were acceptable compared to the negative control sample (spontaneously fermented). The findings also highlight the functional potential of the samples, with PS3 offering benefits for lactose-intolerant individuals and PS2 demonstrating antimicrobial activity. It is possible to offer cucumber pickles to consumers as an alternative probiotic product; however, further research is required to ascertain the viability of probiotics over an extended period.