Alicyclobacillus acidoterrestris is a spore-forming bacterium of importance to the fruit juice industry due to its remarkable heat resistance and production of guaiacol taint. Whole genome sequencing analysis reveals species demarcation corresponds to the two major genotypic groups to which A. acidoterrestris isolates belong. Heat resistance was significantly different between genotypic groups 1 and 2 with D₉₀ values of 15.5 and 9.3 min, respectively (p < 0.01). Comparison of squalene-hopene cyclase (shc) encoding sequences reveals non-synonymous changes and the alteration of glutamine residues. Glutamine absence may link to the stability reinforcement of the enzyme structure against thermal denaturation. Genomic islands harbouring heavy metal resistance genes are found in the majority of genotypic group 1 genomes (63%) but occurs in only one genome (5%) of genotypic group 2. Distribution of the genomic islands in the genotypic groups 1 and 2 is also consistent with phylogenetic trees and ANI and dDDH values. Subsequently, we propose genotypic group 1 as a new species closely related to A. acidoterrestris that possesses enhanced heat resistance.

酸热脂环酸杆菌是一种形成孢子的细菌，对果汁行业具有重要意义，因为它具有出色的耐热性和愈创木酚味。全基因组测序分析显示，物种分界对应于嗜酸曲霉分离株所属的两个主要基因型组。基因型组1和2之间的耐热性显着不同，D ₉₀值分别为15.5和9.3 min（p <0.01）。角鲨烯-戊环化酶（shc）的比较编码序列揭示了非同义的变化和谷氨酰胺残基的改变。谷氨酰胺的缺乏可能与酶结构抗热变性的稳定性增强有关。携带重金属抗性基因的基因组岛在大多数基因型组1基因组中被发现（63％），但仅在基因型组2的一个基因组中出现（5％）。基因组岛在基因型组1和2中的分布也是与系统树和ANI和d DDH值一致。随后，我们提出基因型组1作为与耐热增强的酸曲霉紧密相关的新物种。