AUTHOR=Li Xin-Dong , Lin Yi-Cen , Yang Rui-Si , Kang Xin , Xin Wei-Gang , Wang Feng , Zhang Qi-Lin , Zhang Wen-Ping , Lin Lian-Bing 

TITLE=Genomic and in-vitro characteristics of a novel strain Lacticaseibacillus chiayiensis AACE3 isolated from fermented blueberry

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1168378

DOI=10.3389/fmicb.2023.1168378

ISSN=1664-302X

ABSTRACT=<p>Numerous different species of LAB are used in different fields due to their unique characteristics. However, <italic>Lacticaseibacillus chiayiensis</italic>, a newly established species in 2018, has limited microorganism resources, and lacks comprehensive evaluations of its properties. In this study, <italic>L. chiayiensis</italic> AACE3, isolated from fermented blueberry, was evaluated by genomic analysis and <italic>in vitro</italic> assays of the properties. The genome identified genes associated with biofilm formation (<italic>luxS</italic>, <italic>ccpA</italic>, <italic>brpA</italic>), resistance to oxidative stress (<italic>tpx</italic>, <italic>trxA</italic>, <italic>trxB</italic>, <italic>hslO</italic>), tolerance to acidic conditions (<italic>dltA</italic>, <italic>dltC</italic>), resistance to unfavorable osmotic pressure (<italic>opuBB</italic>, <italic>gbuA</italic>, <italic>gbuB</italic>, <italic>gbuC</italic>), and adhesion (<italic>luxS</italic>, <italic>dltA</italic>, <italic>dltC</italic>). The AACE3 showed 112 unique genes, relative to the other three <italic>L. chiayiensis</italic> strains. Among them, the presence of genes such as <italic>clpP</italic>, <italic>pepO</italic>, and <italic>feoA</italic> suggests a possible advantage of AACE3 over other <italic>L. chiayiensis</italic> in terms of environmental adaptation. <italic>In vitro</italic> evaluation of the properties revealed that AACE3 had robust antibacterial activity against eight common pathogens: <italic>Streptococcus agalactiae</italic>, <italic>Staphylococcus aureus</italic>, <italic>Escherichia coli</italic>, <italic>Salmonella enteritidis</italic>, <italic>Salmonella choleraesuis</italic>, <italic>Shigella flexneri</italic>, <italic>Pseudomonas aeruginosa</italic>, and <italic>Klebsiella pneumoniae</italic>. In addition, AACE3 showed more than 80% survival rate in all tests simulating gastrointestinal fluid, and it exhibited high antioxidant capacity. Interestingly, the cell culture supernatant was superior to intact organisms and ultrasonically crushed bacterial extracts in all tests of antioxidant capacity. These results suggested that the antioxidant capacity may originate from certain metabolites and extracellular enzymes produced by AACE3. Moreover, AACE3 was a moderate biofilm producer due to the self-agglomeration effect. Taken together, <italic>L. chiayiensis</italic> AACE3 appears to be a candidate strain for combating the growing incidence of pathogen infections and antioxidant production.</p>