Bacillus anthracis are gram-positive, non-mobile spores extracellular and inside their host, they exist as vegetative state.It has a single circular chromosome with base pairs of 5,227,293 per DNA molecule with circular double-stranded DNA plasmids, pXO1 and pXO2. (Read,2003)
Video 1-https://www.youtube.com/watchv=7LRGT098lxc#action=share
The trophic level for B. anthracis is heterotrophic and since it is facultative anaerobe, it can be cultured in media with sources of amino acid, carbon, nitrogen and supplementary methionine and thiamine. A defined medium for B. anthracis culture will include glucose, adenine, guanine, thiamine, uracil, calcium and other amino acid sources. (Koehler, 2009)
The bacteria target the hemoglobin since it bound to iron and it is needed for metabolic processes such as growth and reproduction. B. anthracis utilizes hemophores, siderophores and transporter proteins for iron extraction.
Pathogenic mechanism such as inhibiting the normal function of the immune system ,Cytoloysis etc. of B.anthracis. courtesy of https://jamanetwork.com/journals/jama/article-abstract/194886
Inside a host cell, B. anthracis release lysosomal enzymes that lysed the host’s red blood cells, releasing its content, hence the bacterial hemophore takes up the iron released and transfer to their cytosol. Outside of a cell, at low iron levels, B. anthracis produce bacillibactin and petrobactin(siderophores) that have high affinity to iron. The minimal iron available readily binds to the siderophores and are transported via transporter proteins.(Eremenko, 2017; Koppisch et al, 2005; Cendrowski, S. et al, 2004)
B. anthracis thrives best at a temperature of 37°C and at temperatures above 43°C, bacterial growth is halted. At optimum temperature of 37°C, the Cell doubling times range from 30 minutes to 60 minutes in a complex media. (Charlton et al., 2007)
B. anthracis is the causative agent of anthrax, and the type of anthrax is determined by the spore entry into the host. The classification of Anthrax includes cutaneous, gastrointestinal and pulmonary and injection anthrax. (Cendrowski, S. et al,2004) (video 1) When conditions are not favorable, the infectious endospores of B. anthracis are produced .The dormant spores are ideal for bioterrorism since they can withstand any harsh conditions and are easily dispersed without trace.
The sporulation process of Bacillus anthracis.
http://slideplayer.com/slide/5677854/18/images/73/Bacterial+cell+structure+Endospores+(spores)+–+Sporulation.jpg
Binary fission occurs when bacteria g the copied DNA into two and it finally closes off, by forming a cross-wall. The two-daughter cell separate, and they are identical to the mother cell. B. anthracis undergo gene transfer by close contact via conjugation. The virulence plasmids pXO12 and pXO1 can be transferred during conjugation, the bacterial cell with the plasmids become the donor. (Green et al,1989)
We could go, on and on about this amazing bacteria, but time and cyberspace wouldn’t allow.
Bye for now.
Reference:
1. Cendrowski, S., MacArthur, W. and Hanna P. (2004), Bacillus anthracis requires siderophore biosynthesis for growth in macrophages and mouse virulence. Molecular Microbiology, 51: 407-417. doi:10.1046/j.1365-2958.2003.03861.x
2.Charlton, S. , Herbert, M. , McGlashan, J. , King, A. , Jones, P. , West, K. , Roberts, A. , Silman, N. , Marks, T. , Hudson, M. and Hallis, B. (2007), A study of the physiology of Bacillus anthracis Sterne during manufacture of the UK acellular anthrax vaccine. Journal of Applied Microbiology, 103: 1453-1460. doi:10.1111/j.1365-2672.2007.03391.x
3. Eremenko, E.I. (2017)A Bacillus anthracis system for acquisition of heme-bound iron. Microbiol. Virol. (2017) 32: 1. https://doi.org/10.3103/S0891416817010037
4. Koehler T. M. (2009). Bacillus anthracis physiology and genetics. Molecular aspects of medicine, 30(6), 386–396. doi:10.1016/j.mam.2009.07.004
5.Koppisch, A.T., Browder, C.C., Moe, A.L. et al. Biometals (2005) 18: 577. https://doi.org/10.1007/s10534-005-1782-6
6.Read, T. et al (2003) The genome sequence of Bacillus anthracis Ames and comparison to closely related bacteria .NATURE | VOL 423 | © 2003 Nature Publishing Group 81 | www.nature.com/nature. https://deepblue.lib.umich.edu/bitstream/handle/2027.42/62580/nature01586.pdf?sequence=1&isAllowed=y