Editing Bacillus cereus (section)

== Microbiology ==
[[File:Bacillus cereus endospore stain.jpg|thumb|''Bacillus cereus'' endospore stain]]
''B. cereus'' is a [[Bacillus (shape)|rod-shaped]] bacterium with a [[Gram-positive bacteria|Gram-positive]] cell envelope. Depending on the strain, it may be [[Aerobic organism|aerobic]] or [[Facultative anaerobic organism|facultatively anaerobic.]] Most strains are [[Mesophile|mesophilic]], having an optimal temperature between 25&nbsp;°C and 37&nbsp;°C, and neutralophilic, preferring neutral pH, but some have been found to grow in environments with much more extreme conditions.<ref name="Drobniewski-1993">{{Cite journal | vauthors = Drobniewski F |date=October 1993 |title=Bacillus cereus and Related Species | doi = 10.1128/CMR.6.4.324 |journal=American Society for Microbiology |volume=6 |issue=4 |pages=324–338|pmid=8269390 |pmc=358292 }}</ref>

These bacteria are both [[Bacterial spore|spore-forming]] and [[biofilm]]-forming, presenting a large challenge to the food industry due to their contamination capability. Biofilms of ''B. cereus'' most commonly form on air-liquid interfaces or on hard surfaces such as glass. ''B. cereus'' display flagellar motility, which has been shown to aid in biofilm formation via an increased ability to reach surfaces suitable for biofilm formation, to spread the biofilm over a larger surface area, and to recruit planktonic, or single, free-living bacteria.<ref name="Involvement of motility and flagell"/> Biofilm formation may also occur while in spore form due to varying adhesion ability of spores.<ref name="Biology and taxonomy of Bacillus ce">{{cite journal | vauthors = Vilas-Bôas GT, Peruca AP, Arantes OM | title = Biology and taxonomy of Bacillus cereus, Bacillus anthracis, and Bacillus thuringiensis | journal = Canadian Journal of Microbiology | volume = 53 | issue = 6 | pages = 673–687 | date = June 2007 | pmid = 17668027 | doi = 10.1139/W07-029 }}</ref>

Their flagella are [[peritrichous]], meaning there are many flagella located all around the cell body that can bundle together at a single location on the cell to propel it. This flagellar property also allows the cell to change directions of movement depending on where on the cell the flagellum filaments come together to generate movement.<ref name="Biology and taxonomy of Bacillus ce"/><ref>{{cite journal | vauthors = Riley EE, Das D, Lauga E | title = Swimming of peritrichous bacteria is enabled by an elastohydrodynamic instability | journal = Scientific Reports | volume = 8 | issue = 1 | pages = 10728 | date = July 2018 | pmid = 30013040 | doi = 10.1038/s41598-018-28319-8 | pmc = 6048115 | arxiv = 1806.01902 | bibcode = 2018NatSR...810728R }}</ref>

Some studies and observations have shown that silica particles the size of a few nanometers have been deposited in a spore coat layer in the extracytoplasmic region of the ''Bacillus cereus'' spore. The layer was first discovered by the use of scanning transmission electron microscopy (STEM), however the images taken did not have resolution high enough to determine the precise location of the silica. Some investigators hypothesize that the layer helps different spores from sticking together. It has also been shown to provide some resistance to acidic environments. The silica coat is related to the permeability of the spore's inner membrane. Strong mineral acids are able to break down spore permeability barriers and kill the spore. However, when the spore has a silica coating, it may reduce the permeability of the membrane and provide resistance to many acids.<ref>{{Cite journal |last1=Hirota |first1=Ryuichi |last2=Hata |first2=Yumehiro |last3=Ikeda |first3=Takeshi |last4=Ishida |first4=Takenori |last5=Kuroda |first5=Akio |date=January 2010 |title=The Silicon Layer Supports Acid Resistance of Bacillus cereus Spores |journal=Journal of Bacteriology |volume=192 |issue=1 |pages=111–116 |doi=10.1128/JB.00954-09 |issn=0021-9193 |pmc=2798246 |pmid=19880606}}</ref>

=== Metabolism ===
''Bacillus cereus'' has mechanisms for both aerobic and anaerobic respiration, making it a [[Facultative anaerobic organism|facultative anaerobe]].<ref name="microbewiki.kenyon.edu">{{Cite web |title=Bacillus cereus - microbewiki |url=https://microbewiki.kenyon.edu/index.php/Bacillus_cereus#:~:text=substrate%20level%20phosphorylation.-,B.,acids%20for%20growth%20and%20energy. |access-date=2022-11-16 |website=microbewiki.kenyon.edu |language=en}}</ref> Its aerobic pathway consists of three terminal oxidases: cytochrome aa3, cytochrome caa3, and cytochrome bd, the use of each dependent on the amount of oxygen present in the environment.<ref>{{Cite journal |last1=Chateau |first1=Alice |last2=Alpha-Bazin |first2=Béatrice |last3=Armengaud |first3=Jean |last4=Duport |first4=Catherine |date=18 Jan 2022 |title=Heme A Synthase Deficiency Affects the Ability of Bacillus cereus to Adapt to a Nutrient-Limited Environment |journal=International Journal of Molecular Sciences |language=en |volume=23 |issue=3 |pages=1033 |doi=10.3390/ijms23031033 |pmid=35162964 |pmc=8835132 |issn=1422-0067|doi-access=free }}</ref> The ''B. cereus'' genome encodes genes for metabolic enzymes including NADH dehydrogenases, succinate dehydrogenase, complex III, and cytochrome c oxidase, as well as others. ''Bacillus cereus'' can metabolize several different compounds to create energy, including carbohydrates, proteins, peptides, and amino acids.<ref name="microbewiki.kenyon.edu" />

The Embden-Meyerhof pathway is the predominant pathway used by ''Bacillus cereus'' to catabolize glucose at every stage of the cell's development, according to estimates of a radiorespirometric method of glucose catabolism. This is true at times of germinative phases, as well as sporogenic phases. At the filamentous, granular, forespore, and transitional stages, the Embden-Meyerhof pathway was responsible for the catabolism of 98% of the cell's glucose. The remainder of the glucose was catabolized by the hexose monophosphate oxidative pathway.<ref>{{Cite journal |last1=Goldman |first1=Manuel |last2=Blumenthal |first2=Harold J. |title=Pathways of Glucose Catabolism in Bacillus Cereus |date=February 1964 |journal=Journal of Bacteriology |volume=87 |issue=2 |pages=377–386 |doi=10.1128/jb.87.2.377-386.1964 |issn=0021-9193 |pmid=14151060|pmc=277019 }}</ref>

Analysis of the core genome of ''B. cereus'' reveals a limited presence of enzymes meant for breakdown of [[polysaccharide]]s and a prevalence of [[protease]]s and amino acid degradation and transport pathways, indicating that their preferred diet consists of proteins and their breakdown products.<ref>{{cite journal |display-authors=6 |vauthors=Ivanova N, Sorokin A, Anderson I, Galleron N, Candelon B, Kapatral V, Bhattacharyya A, Reznik G, Mikhailova N, Lapidus A, Chu L, Mazur M, Goltsman E, Larsen N, D'Souza M, Walunas T, Grechkin Y, Pusch G, Haselkorn R, Fonstein M, Ehrlich SD, Overbeek R, Kyrpides N |date=May 2003 |title=Genome sequence of Bacillus cereus and comparative analysis with Bacillus anthracis |journal=Nature |volume=423 |issue=6935 |pages=87–91 |doi=10.1038/nature01582 |pmid=12721630|bibcode=2003Natur.423...87I |s2cid=4361366 |doi-access=free }}</ref>

An isolate of a bacterium found to produce [[Polyhydroxybutyrate|PHBs]] was identified as ''B. cereus'' through analysis of 16S rRNA sequences as well as similarity of morphological and biochemical characteristics. PHBs may be produced when there is excess carbon or limited essential nutrients present in the environment, and they are later broken down by the microbe as a fuel source under starvation conditions. This indicates the potential role of ''B. cereus'' in producing biodegradable plastic substitutes. PHB production was highest when provided with glucose as a carbon source.<ref>{{cite journal | vauthors = Hamdy SM, Danial AW, Gad El-Rab SM, Shoreit AA, Hesham AE | title = Production and optimization of bioplastic (Polyhydroxybutyrate) from Bacillus cereus strain SH-02 using response surface methodology | journal = BMC Microbiology | volume = 22 | issue = 1 | pages = 183 | date = July 2022 | pmid = 35869433 | pmc = 9306189 | doi = 10.1186/s12866-022-02593-z | doi-access = free }}</ref>