Table 1_Assessment of genomic and antifungal properties of Lactococcus garvieae ZB15 isolated from Zhenba bacon.docx

IntroductionLactic acid bacteria (LAB) have attracted significant interest as natural antimicrobials for food safety and preservation. Some LAB strains effectively inhibit food-borne molds and yeasts responsible for spoilage and mycotoxin contamination. However, the antifungal effect of Lactococcus garvieae remains largely unexplored.
MethodsThis study investigates the properties of L. garvieae ZB15 isolated from Zhenba bacon, emphasizing its genetic safety and antimicrobial potential. The genomic information and antifungal properties of Lactococcus garvieae strain ZB15 were comprehensively analyzed using whole-genome sequencing and in vitro experiments.
ResultsGenomic analysis confirmed the absence of virulence and antibiotic resistance genes, along with minimal prophage presence, underscoring its safety for application. The strain exhibited strong self-aggregation, co-aggregation, and hydrophobic properties, suggesting its potential for intestinal adhesion. The cell-free supernatant (CFS) of L. garvieae ZB15 demonstrated notable antifungal activity, achieving over 50% inhibition against four fungal strains at 60 mg/mL. The antifungal compounds in the CFS retained high activity after thermal treatment at 100°C for 1 hour, highlighting their thermal stability. Additionally, enzymatic treatments with trypsin, pepsin, and proteinase K, along with neutralization of organic acids, significantly reduced the antifungal activity, indicating the involvement of proteinaceous compounds and organic acids. Catalase treatment partially affected antifungal activity, suggesting hydrogen peroxide as a contributing factor.
DiscussionLactococcus garvieae ZB15 possessed probiotic characteristics, including strong adhesion properties and pathogen exclusion capabilities. The strain’s genetic safety, lack of antibiotic resistance genes, and ability to produce heat-stable antifungal compounds highlighted its potential as a natural food preservative.

引言 乳酸菌（Lactic acid bacteria, LAB）作为用于食品安全与食品保鲜的天然抗菌剂，已受到广泛关注。部分LAB菌株可有效抑制导致食品腐败与真菌毒素污染的食源性霉菌和酵母菌。然而，格氏乳球菌（Lactococcus garvieae）的抗真菌活性迄今仍鲜有研究。方法 本研究针对从镇巴腊肉中分离得到的格氏乳球菌ZB15菌株开展研究，重点解析其遗传安全性与抗菌潜力。通过全基因组测序与体外实验，全面分析格氏乳球菌ZB15的基因组信息与抗真菌特性。结果 基因组分析结果显示，该菌株无毒力基因与抗生素抗性基因，且前噬菌体含量极低，证实其应用安全性良好。该菌株表现出较强的自凝集、共凝集与疏水特性，提示其具备肠道黏附潜力。格氏乳球菌ZB15的无细胞上清液（cell-free supernatant, CFS）展现出显著的抗真菌活性：在浓度为60 mg/mL时，对4种真菌菌株的抑制率均超过50%。该上清液中的抗真菌成分经100℃热处理1小时后仍保持较高活性，表明其热稳定性优异。此外，经胰蛋白酶、胃蛋白酶、蛋白酶K处理，以及中和有机酸后，抗真菌活性显著降低，提示该活性由蛋白类物质与有机酸共同介导；过氧化氢酶处理可部分削弱抗真菌活性，表明过氧化氢也参与了抗真菌过程。讨论 格氏乳球菌ZB15具备多项益生特性，包括较强的黏附能力与病原菌排斥能力。该菌株遗传安全、无抗生素抗性基因，且可产生热稳定的抗真菌成分，表明其具备开发为天然食品防腐剂的应用潜力。