Data_Sheet_1_Levilactobacillus brevis, autochthonous to cucumber fermentation, is unable to utilize citric acid and encodes for a putative 1,2-propanediol utilization microcompartment.pdf

The metabolic versatility of Levilactobacillus brevis, a heterofermentative lactic acid bacterium, could benefit environmentally compatible and low salt cucumber fermentation. The biodiversity of Lvb. brevis autochthonous to cucumber fermentation was studied using genotypic and phenotypic analyses to identify unique adjunct cultures. A group of 131 isolates autochthonous to industrial fermentations was screened using rep-PCR-(GTG)5 and a fermentation ability assay under varied combinations of salt (0 or 6%), initial pH (4.0 or 5.2), and temperature (15 or 30°C). No apparent similarities were observed among the seven and nine clusters in the genotypic and phenotypic dendrograms, respectively. A total of 14 isolates representing the observed biodiversity were subjected to comparative genome analysis. The autochthonous Lvb. brevis clustered apart from allochthonous isolates, as their genomes lack templates for citrate lyase, several putative hypothetical proteins, and some plasmid- and phage-associated proteins. Four and two representative autochthonous and allochthonous Lvb. brevis, respectively, were subjected to phenotype microarray analysis using an Omnilog. Growth of all Lvb. brevis strains was supported to various levels by glucose, fructose, gentiobiose, 1,2-propanediol, and propionic acid, whereas the allochthonous isolate ATCC14890 was unique in utilizing citric acid. All the Lvb. brevis genomes encode for 1,2-propanediol utilization microcompartments. This study identified a unique Lvb. brevis strain, autochthonous to cucumber, as a potential functional adjunct culture for commercial fermentation that is distinct in metabolic activities from allochthonous isolates of the same species.

作为一种异型发酵乳酸菌，短乳杆菌（Levilactobacillus brevis）的代谢多样性可助力环境友好型低盐黄瓜发酵。本研究通过基因型与表型分析，对黄瓜发酵体系中土著短乳杆菌的生物多样性展开研究，以筛选独特的辅助发酵剂。研究团队采用重复序列PCR-(GTG)5（rep-PCR-(GTG)5）技术，以及在盐浓度（0%或6%）、初始pH（4.0或5.2）、温度（15℃或30℃）的不同组合条件下开展的发酵能力测定实验，对131株工业发酵体系中分离得到的土著菌株进行了筛选。基因型聚类树与表型聚类树分别划分出7个与9个簇，各簇之间未显现出明显相似性。最终选取14株可代表该物种多样性的菌株开展比较基因组分析。土著短乳杆菌与异源分离株的聚类结果相互分离，究其原因，前者基因组缺失柠檬酸裂解酶的编码模板、多种假定蛋白，以及部分质粒与噬菌体相关蛋白。分别选取4株土著短乳杆菌与2株异源短乳杆菌作为代表菌株，采用Omnilog微生物表型芯片系统开展表型微阵列分析。葡萄糖、果糖、龙胆二糖、1,2-丙二醇与丙酸可在不同程度上支持所有短乳杆菌菌株的生长，而异源分离株ATCC14890则是唯一可利用柠檬酸的菌株。所有短乳杆菌的基因组均编码1,2-丙二醇利用细菌微区室。本研究筛选得到一株独特的黄瓜源土著短乳杆菌，其代谢活性与该物种的异源分离株存在显著差异，可作为商业化发酵的潜在功能性辅助发酵剂。