Sarjit Amreeta, Ravensdale Joshua T, Coorey Ranil, Fegan Narelle, Dykes Gary A
School of Public Health, Curtin University, Bentley, Western Australia, Australia.
CSIRO Agriculture and Food, Brisbane, Queensland, Australia.
Curr Microbiol. 2021 May;78(5):1741-1751. doi: 10.1007/s00284-021-02443-7. Epub 2021 Mar 18.
Clustered regularly interspaced short palindromic repeats (CRISPR) cas genes have been linked to stress response in Salmonella. Our aim was to identify the presence of CRISPR cas in Salmonella and its response to heat in the presence of iron. Whole genomes of Salmonella (n = 50) of seven serovars were compared to identify the presence of CRISPR cas genes, direct-repeats and spacers. All Salmonella genomes had all cas genes present except S. Newport 2393 which lacked these genes. Gene-specific primers were used to confirm the absence of these genes in S. Newport 2393. The presence/absence of CRISPR cas genes was further investigated among 469 S. Newport genomes from PATRIC with 283 genomes selected for pan-genome analysis. The response of eleven Salmonella strains of various serovars to gradual heat in ferrous and ferric forms of iron was investigated. A total of 32/283 S. Newport genomes that lacked all CRISPR cas genes clustered together. S. Newport 2393 was the most heat-sensitive strain at higher iron levels (200 and 220 pm) in ferrous and ferric forms of iron. The absence of CRISPR cas genes in S. Newport 2393 may contribute to its increase in heat sensitivity and iron may play a role in this. The high reduction in numbers of most Salmonella strains exposed to heat makes it unfeasible to extract RNA and conduct transcription studies. Further studies should be conducted to validate the survival of Salmonella when exposed to heat in the presence/absence of CRISPR cas genes and different iron levels.
成簇规律间隔短回文重复序列（CRISPR）相关的cas基因与沙门氏菌的应激反应有关。我们的目的是确定沙门氏菌中CRISPR cas的存在情况及其在铁存在下对热的反应。比较了七种血清型沙门氏菌（n = 50）的全基因组，以确定CRISPR cas基因、直接重复序列和间隔序列的存在情况。除纽波特沙门氏菌2393株缺乏这些基因外，所有沙门氏菌基因组均存在所有cas基因。使用基因特异性引物证实纽波特沙门氏菌2393株中不存在这些基因。在来自PATRIC的469个纽波特沙门氏菌基因组中进一步研究了CRISPR cas基因的存在/缺失情况，其中283个基因组被选用于泛基因组分析。研究了11株不同血清型沙门氏菌对亚铁和铁离子形式的铁逐渐升温的反应。共有32/283个缺乏所有CRISPR cas基因的纽波特沙门氏菌基因组聚集在一起。在亚铁和铁离子形式的铁含量较高（200和220 pm）时，纽波特沙门氏菌2393株是最热敏的菌株。纽波特沙门氏菌2393株中CRISPR cas基因的缺失可能导致其热敏性增加，铁可能在此过程中发挥作用。大多数暴露于热的沙门氏菌菌株数量大幅减少，使得提取RNA并进行转录研究变得不可行。应进一步开展研究，以验证沙门氏菌在存在/不存在CRISPR cas基因及不同铁含量情况下受热时的存活情况。
