Decoding the anomalies: a genome-based analysis of Bacillus cereus group strains closely related to Bacillus anthracis
IntroductionThe Bacillus cereus group encompasses a complex group of closely related pathogenic and non-pathogenic bacterial species. Key members include B. anthracis, B. cereus, and B. thuringiensis organisms that, despite genetic proximity, diverge significantly in morphology and pathogenic potent...
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Frontiers Media S.A.
2025-02-01
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| Series: | Frontiers in Microbiology |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fmicb.2025.1527049/full |
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| author | Thuto Gomolemo Magome Marius Surleac Marius Surleac Ayesha Hassim Cornelius Carlos Bezuidenhout Henriette van Heerden Kgaugelo Edward Lekota |
| author_facet | Thuto Gomolemo Magome Marius Surleac Marius Surleac Ayesha Hassim Cornelius Carlos Bezuidenhout Henriette van Heerden Kgaugelo Edward Lekota |
| author_sort | Thuto Gomolemo Magome |
| collection | DOAJ |
| description | IntroductionThe Bacillus cereus group encompasses a complex group of closely related pathogenic and non-pathogenic bacterial species. Key members include B. anthracis, B. cereus, and B. thuringiensis organisms that, despite genetic proximity, diverge significantly in morphology and pathogenic potential. Taxonomic challenges persist due to inconsistent classification methods, particularly for B. cereus isolates that resemble B. anthracis in genetic clustering.MethodsThis study investigated B. cereus group isolates from blood smears of animal carcasses in Kruger National Park, uncovering an unusual isolate with B. cereus features based on classical microbiological tests yet B. anthracis-like genomic similarities with an Average Nucleotide Identity (ANI) of ≥95%. Using comparative genomics, pan-genomics and whole genome Single Nucleotide Polymorphism (wgSNP) analysis, a total of 103 B. cereus group genomes were analyzed, including nine newly sequenced isolates from South Africa and a collection of isolates that showed some classification discrepancies, thus classified as “anomalous.”Results and discussionOf the 36 strains identified as B. anthracis in GenBank, 26 clustered phylogenetically with the four confirmed B. anthracis isolates from South Africa and shared 99% ANI. Isolates with less than 99% ANI alignment to B. anthracis exhibited characteristics consistent with B. cereus and/or B. thuringiensis, possessing diverse genetic profiles, insertion elements, resistance genes, and virulence genes features, contrasting with the genetic uniformity of typical B. anthracis. The findings underscore a recurrent acquisition of mobile genetic elements within B. cereus and B. thuringiensis, a process infrequent in B. anthracis.ConclusionThis study highlights the pressing need for standardized taxonomic criteria in B. cereus group classification, especially as anomalous isolates emerge. This study supports the existing nomenclature framework which offers an effective solution for classifying species into genomospecies groups. We recommend isolates with ANI ≥99% to standard reference B. anthracis be designated as typical B. anthracis in GenBank to maintain taxonomic clarity and precision. |
| format | Article |
| id | doaj-art-667236b2372643f8a4505fbd3178c940 |
| institution | Kabale University |
| issn | 1664-302X |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Microbiology |
| spelling | doaj-art-667236b2372643f8a4505fbd3178c9402025-02-05T07:32:04ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2025-02-011610.3389/fmicb.2025.15270491527049Decoding the anomalies: a genome-based analysis of Bacillus cereus group strains closely related to Bacillus anthracisThuto Gomolemo Magome0Marius Surleac1Marius Surleac2Ayesha Hassim3Cornelius Carlos Bezuidenhout4Henriette van Heerden5Kgaugelo Edward Lekota6Unit for Environmental Sciences and Management, Microbiology, North-West University, Potchefstroom, South AfricaThe Research Institute of the University of Bucharest, Bucharest, RomaniaNational Institute for Infectious Diseases “Matei Balș”, Bucharest, RomaniaDepartment of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South AfricaUnit for Environmental Sciences and Management, Microbiology, North-West University, Potchefstroom, South AfricaDepartment of Veterinary Tropical Diseases, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, South AfricaUnit for Environmental Sciences and Management, Microbiology, North-West University, Potchefstroom, South AfricaIntroductionThe Bacillus cereus group encompasses a complex group of closely related pathogenic and non-pathogenic bacterial species. Key members include B. anthracis, B. cereus, and B. thuringiensis organisms that, despite genetic proximity, diverge significantly in morphology and pathogenic potential. Taxonomic challenges persist due to inconsistent classification methods, particularly for B. cereus isolates that resemble B. anthracis in genetic clustering.MethodsThis study investigated B. cereus group isolates from blood smears of animal carcasses in Kruger National Park, uncovering an unusual isolate with B. cereus features based on classical microbiological tests yet B. anthracis-like genomic similarities with an Average Nucleotide Identity (ANI) of ≥95%. Using comparative genomics, pan-genomics and whole genome Single Nucleotide Polymorphism (wgSNP) analysis, a total of 103 B. cereus group genomes were analyzed, including nine newly sequenced isolates from South Africa and a collection of isolates that showed some classification discrepancies, thus classified as “anomalous.”Results and discussionOf the 36 strains identified as B. anthracis in GenBank, 26 clustered phylogenetically with the four confirmed B. anthracis isolates from South Africa and shared 99% ANI. Isolates with less than 99% ANI alignment to B. anthracis exhibited characteristics consistent with B. cereus and/or B. thuringiensis, possessing diverse genetic profiles, insertion elements, resistance genes, and virulence genes features, contrasting with the genetic uniformity of typical B. anthracis. The findings underscore a recurrent acquisition of mobile genetic elements within B. cereus and B. thuringiensis, a process infrequent in B. anthracis.ConclusionThis study highlights the pressing need for standardized taxonomic criteria in B. cereus group classification, especially as anomalous isolates emerge. This study supports the existing nomenclature framework which offers an effective solution for classifying species into genomospecies groups. We recommend isolates with ANI ≥99% to standard reference B. anthracis be designated as typical B. anthracis in GenBank to maintain taxonomic clarity and precision.https://www.frontiersin.org/articles/10.3389/fmicb.2025.1527049/fullBacillus cereus groupBacillus anthraciswhole genome sequencingpan-genomicsaverage nucleotide identity |
| spellingShingle | Thuto Gomolemo Magome Marius Surleac Marius Surleac Ayesha Hassim Cornelius Carlos Bezuidenhout Henriette van Heerden Kgaugelo Edward Lekota Decoding the anomalies: a genome-based analysis of Bacillus cereus group strains closely related to Bacillus anthracis Frontiers in Microbiology Bacillus cereus group Bacillus anthracis whole genome sequencing pan-genomics average nucleotide identity |
| title | Decoding the anomalies: a genome-based analysis of Bacillus cereus group strains closely related to Bacillus anthracis |
| title_full | Decoding the anomalies: a genome-based analysis of Bacillus cereus group strains closely related to Bacillus anthracis |
| title_fullStr | Decoding the anomalies: a genome-based analysis of Bacillus cereus group strains closely related to Bacillus anthracis |
| title_full_unstemmed | Decoding the anomalies: a genome-based analysis of Bacillus cereus group strains closely related to Bacillus anthracis |
| title_short | Decoding the anomalies: a genome-based analysis of Bacillus cereus group strains closely related to Bacillus anthracis |
| title_sort | decoding the anomalies a genome based analysis of bacillus cereus group strains closely related to bacillus anthracis |
| topic | Bacillus cereus group Bacillus anthracis whole genome sequencing pan-genomics average nucleotide identity |
| url | https://www.frontiersin.org/articles/10.3389/fmicb.2025.1527049/full |
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