Abstract：
Virgibacillus spp. stand out as a potent starter culture for accelerating the fermention of fish sauces and shrimp pastes. However, the underlying molecular mechanisms responsible for their adaptation and biotechnological potential remain elusive. Therefore, the present study focuses on phenotypic and genomic analyses of a halophilic bacterium Virgibacillus dokdonensis T4.6, derived from Vietnamese high-salt fermented shrimp paste. The draft genome contained 4,096,868 bp with 3780 predicted coding sequences. Genome mining revealed the presence of 143 genes involved in osmotic adaptation explaining its resistant phenotype to 24% (w/v) NaCl. Among them, 37 genes making up the complete ectoine metabolism pathway, confirmed its ability to produce 4.38 ± 0.29 wt% ectoine under 12.5% NaCl stress. A significant finding was the identification of 39 genes responsible for an entire degradation pathway of the toxic biogenic amine histamine, which was in agreement with its histamine degradation rate of 42.7 ± 2.1% in the HA medium containing 5 mM histamine within 10 days at 37 °C. Furthermore, 114 proteolytic and 19 lipolytic genes were detected which might contribute to its survival as well as the nutrient quality and flavor of shrimp paste. Of note, a putative gene vdo2592 was found as a possible novel lipase/esterase due to its unique Glycine-Aspartate-Serine-Leucine (GDSL) sequence motif. This is the first report to reveal the adaptative strategies and related biotechnological potential of Virgibacillus associated with femented foods. Our findings indicated that V. dokdonensis T4.6 is a promising starter culture for the production of fermented shrimp paste products.
摘要：
Virgibacillusspp.作为一种有效的发酵剂，可以加速鱼酱和虾酱的发酵。然而,负责其适应和生物技术潜力的潜在分子机制仍然难以捉摸。因此,本研究的重点是来自越南高盐发酵虾酱的嗜盐细菌dokdonensisT4.6的嗜盐细菌的表型和基因组分析。基因组草案包含4,096,868bp和3780个预测编码序列。基因组挖掘显示存在143个参与渗透适应的基因，解释了其对24％（w/v）NaCl的抗性表型。其中,37个基因组成了完整的异位代谢途径，证实了其在12.5％NaCl胁迫下产生4.38±0.29wt％的异黄酮的能力。一个重要的发现是鉴定了39个负责毒性生物胺组胺整个降解途径的基因，这与在37°C下10天内含有5mM组胺的HA培养基中42.7±2.1%的组胺降解率一致。此外，检测到114个蛋白水解基因和19个脂解基因，这可能有助于其存活以及虾酱的营养品质和风味。值得注意的是，由于其独特的甘氨酸-天冬氨酸-丝氨酸-亮氨酸（GDSL）序列基序，推测的基因vdo2592被发现为可能的新型脂肪酶/酯酶。这是第一份揭示与女性食品相关的Virgibacillus的适应性策略和相关生物技术潜力的报告。我们的发现表明V.dokdonensisT4.6是生产发酵虾酱产品的有前途的发酵剂。
