Probiotic potential of lactic acid bacteria obtained from fermented curly kale juice

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ORIGINAL PAPER

Probiotic potential of lactic acid bacteria obtained from fermented curly kale juice Julia Szutowska1   · Daniela Gwiazdowska1  Received: 4 August 2020 / Revised: 6 October 2020 / Accepted: 13 October 2020 © The Author(s) 2020

Abstract The aim of the paper was to analyse changes in lactic acid bacteria (LAB) populations during spontaneous fermentation of green curly kale juice (Brasicca oleracea L. var. acephala L.) and to determine the probiotic potential of LAB isolates. The analyses revealed that changes in LAB populations were specific for spontaneously fermented vegetable juices. The initial microbiota, composed mostly of Leuconostoc mesenteroides bacteria, was gradually replaced by Lactobacillus species, mainly Lactobacillus plantarum, Lactobacillus sakei, and Lactobacillus coryniformis. Screening tests for the antimicrobial properties and antibiotic susceptibility of isolates allowed for the selection of 12 strains with desirable characteristics. L. plantarum isolates were characterized by the widest spectrum of antimicrobial interactions, both towards Gram-positive and Gram-negative bacteria. Also, L. plantarum strains exhibited the best growth abilities under low pH conditions, and at different NaCl and bile salt concentrations. All strains showed different levels of antibiotic sensitivity, although they were resistant to vancomycin and kanamycin. The present study has shown that bacterial isolates obtained from spontaneously fermented kale juice could constitute valuable probiotic starter cultures, which may be used in fermentation industry. Keywords  Non-dairy fermented juice · Spontaneous fermentation · MALDI-TOF spectrometry · Antimicrobial properties · Antibiotic susceptibility assay · Functional properties

Introduction In recent years, the number of studies involving the isolation of autochthonous plant microorganisms, especially LAB, and determination of their functional properties has been growing, both in the fermented food industry and in scientific research. In this context, many scientific explorations involved intensive investigation of novel fermented plant materials, such as curly kale, cactus pear, red dragon fruit, or cherry, as well as traditional fermented foods, e.g. kimchi or sauerkraut. Both novel and traditional plant materials constitute promising sources of new unique probiotic candidates (Beganović et al. 2014; Filannino et al. 2015; Michalak et al. 2018; Verón et al. 2019; Yien Ong et al. 2012). Basically, Communicated by Erko Stackebrandt. * Julia Szutowska [email protected] 1



Department of Natural Science and Quality Assurance, Institute of Quality Science, Poznań University of Economics and Business, Poznań, Poland

autochthonous microorganisms may be isolated from raw, unfermented plants, as well as during different stages of spontaneous fermentation. The population of microorganisms is characteristic for a specific plant niche and depends on numerous factors like weather, geographical location, harvesting conditions, or plant maturity stage (