Comparative genetic and physiological characterisation of Pectinatus species reveals shared tolerance to beer-associated stressors but halotolerance specific to pickle-associated strains. Pectinatus frisingensis strain:MB139 | isolate:MB139

Obligate anaerobic bacteria from the genus Pectinatus have been known to cause beer spoilage for over 40 years. Whole genome sequencing was performed on eleven beer spoilage strains (nine Pectinatus frisingensis, one Pectinatus cerevisiiphilus and one Pectinatus haikarae isolate), as well as two pickle spoilage species (Pectinatus brassicae and Pectinatus sottacetonis) and the tolerance of all species to a range of environmental conditions was tested. Exploration of metabolic pathways for carbohydrates, amino acids and vitamins showed little difference between beer spoilage- and pickle spoilage-associated species. However, genes for certain carbohydrate and sulphur-containing amino acid associated enzymes were only present in the beer spoilage group and genes for specific transporters and regulatory genes were uniquely found in the pickle spoilage group. Transporters for compatible solutes, only present in pickle-associated strains, likely explain their experimentally observed higher halotolerance compared to the beer spoilers. Genes involved in biofilm formation and ABC-transporters potentially capable of exporting hop-derived antimicrobial compounds were found in all strains. All species grew in the presence of alcohol up to 5% alcohol by volume (ABV) and hops extract up to 80 ppm. Therefore, the species isolated from pickle processes may pose novel hazards in brewing.

专性厌氧果胶杆菌属（Pectinatus）细菌引发啤酒变质的现象已被学界认知超过40年。本研究对11株啤酒变质菌株（9株弗氏果胶杆菌（Pectinatus frisingensis）、1株啤酒果胶杆菌（Pectinatus cerevisiiphilus）与1株海卡拉果胶杆菌（Pectinatus haikarae）），以及2株泡菜变质菌株（芸苔果胶杆菌（Pectinatus brassicae）和索氏乙酸果胶杆菌（Pectinatus sottacetonis））完成了全基因组测序，并检测了所有供试菌株对一系列环境条件的耐受能力。针对碳水化合物、氨基酸及维生素的代谢通路进行探究后发现，啤酒变质相关菌株与泡菜变质相关菌株的代谢特征差异微弱。不过，部分与碳水化合物及含硫氨基酸相关的酶编码基因仅存在于啤酒变质菌株类群中，而特定转运蛋白编码基因与调控基因则仅在泡菜变质菌株类群中被检出。仅在泡菜相关菌株中存在的相容性溶质转运蛋白，或可解释实验观测到的其相较于啤酒变质菌株更高的耐盐性。所有供试菌株中均检出参与生物膜形成的基因，以及可介导啤酒花来源抗菌物质输出的ABC转运蛋白（ABC-transporter）编码基因。所有菌株均可在体积分数最高达5%的乙醇（Alcohol by Volume, ABV）环境，以及浓度最高达80 ppm的啤酒花提取物中生长。因此，从泡菜加工流程中分离得到的果胶杆菌属菌株，可能在酿造工业中构成新型食品安全风险。