Rana A Y K M Masud, Islam Safaiatul, Kamal Abu Hena Mostofa, Narumi Issay
Molecular Radiobiology and Biodosimetry Division, Institute of Food and Radiation Biology, Atomic Energy Research Establishment, Savar, Dhaka 1349, Bangladesh.
Molecular Radiobiology and Biodosimetry Division, Institute of Food and Radiation Biology, Atomic Energy Research Establishment, Savar, Dhaka 1349, Bangladesh.
Infect Genet Evol. 2025 Sep;133:105796. doi: 10.1016/j.meegid.2025.105796. Epub 2025 Jul 8.
This study isolated a radiation-resistant Bacillus species from the pool water of a Co gamma irradiator. The bacterium was motile, a spore-former, rod-shaped, Gram-positive, and capable of withstanding 5 kGy of gamma radiation. Based on 16S rRNA gene sequencing, MLST, and gyrB gene phylogeny, the isolate was classified within the B. cereus group. Comparative whole-genome analysis demonstrated a high level nucleotide identity with B. cereus AH820 (99.49 %), B. anthracis (98.59-98.81 %), and B. cereus type strain ATCC 14579 (91.70 %). Despite the chromosomal similarity to B. cereus AH820, the isolate lacked the emetic toxin-producing plasmid (PER_AH820) and phenotypic traits of B. anthracis, such as enterotoxin production and penicillin resistance. In silico DNA-DNA hybridization (DDH) assays showed 88.4 % genome similarity to B. anthracis, while showing a lower similarity (44.7 %) to B. cereus. Detection of non-B. anthracis ancestral "G" allele in the plcR gene further excluded its identification as B. anthracis. Whole-genome phylogenetic analysis clustered the isolate with B. cereus strains previously identified from the International Space Station (ISS) and pathogenic variants of B. cereus. The isolate was designated as B. cereus strain mrbd.
本研究从钴源伽马辐照器的池水中分离出一种抗辐射芽孢杆菌。该细菌具有运动性，能形成芽孢，呈杆状，革兰氏阳性，能够耐受5千戈瑞的伽马辐射。基于16S rRNA基因测序、多位点序列分型（MLST）和gyrB基因系统发育分析，该分离株被归类于蜡样芽孢杆菌群。比较全基因组分析表明，其与蜡样芽孢杆菌AH820（99.49%）、炭疽芽孢杆菌（98.59 - 98.81%）和蜡样芽孢杆菌模式菌株ATCC 14579（91.70%）具有高度的核苷酸同一性。尽管该分离株在染色体上与蜡样芽孢杆菌AH820相似，但它缺乏产呕吐毒素的质粒（PER_AH820）以及炭疽芽孢杆菌的表型特征，如产肠毒素和对青霉素耐药。电子DNA - DNA杂交（DDH）分析显示，其与炭疽芽孢杆菌的基因组相似性为88.4%，而与蜡样芽孢杆菌的相似性较低（44.7%）。在plcR基因中检测到非炭疽芽孢杆菌祖先的“G”等位基因，进一步排除了将其鉴定为炭疽芽孢杆菌的可能性。全基因组系统发育分析将该分离株与先前从国际空间站（ISS）鉴定出的蜡样芽孢杆菌菌株以及蜡样芽孢杆菌的致病变体归为一类。该分离株被命名为蜡样芽孢杆菌菌株mrbd。
