Bacillus subtilis is a rod-shaped, Gram-positive bacterium commonly found in soil. It forms endospores that allow it to survive harsh environmental conditions. While traditionally considered an aerobe, recent studies have shown it can also grow anaerobically using various electron acceptors. B. subtilis is a model organism used to study processes like chromosome replication, cellular differentiation, and sporulation. It is also used industrially to produce secreted enzymes on a large scale.

1. Bacillus subtilis:
o Bacillus subtilis, alsoknown as the haybacillus orgrass bacillus.
o It isa Gram-positive,catalase-positivebacterium.
o Its foundinsoil andthe gastrointestinal tractof ruminantsandhumans.
o A memberof the genus Bacillus,
o These are endosporesproducingbacteria.
o These endosporesprotectsthe bacteria fromtolerate extreme environmental conditions.
o B.Bubtilis are obligativeaerobe.
o B. subtilis has historicallybeenclassifiedasan obligate aerobe,thoughevidence existsthatitis
a facultative aerobe.
o B. subtilis isconsideredthe beststudiedGram-positivebacterium.
o B.Subtilisis model organism tostudybacterial chromosome replicationandcell differentiation.
o It isone of the bacterial championsinsecretedenzyme productionandusedonanindustrial
scale by biotechnology
There wasa long-heldbelief thatthe gram-positive soilbacterium Bacillussubtilisisastrictaerobe.But
recentstudieshave shownthatB. subtiliswill grow anaerobically,eitherbyusingnitrate ornitrite asa
terminal electronacceptor,orbyfermentation.
In termsof popularityasa laboratorymodel organism, B.subtilisisoftenusedasthe Gram-
positive equivalentof Escherichiacoli,anextensivelystudied Gram-negativebacterium.
The most well knowndisease causedbybacilliis anthrax,causedbyBacillus anthracis.Anthrax has a
longhistorywithhumans.
Bacillussubtilisare rod-shapedbacteriathatare Gram-positive (Perez2000). The cell wall isa rigid
structure outside the cell.Itiscomposedof peptidoglycan,whichisapolymerof sugarsand amino
acids. The peptidoglycanthatisfoundinbacteriaisknownas murein.
 cientific classifSication
Kingdom : Bacteria
Phylum: Firmicutes
Class: Bacilli
Order: Bacillates
Family: Bacillaceae
Genes : Bacillus pumilus
Binomial name: Bacillus pumilus

2.  Description:
Bacillus subtilis is a Gram-positive bacterium, rod-shapedandcatalase-positive.Itwasoriginally
namedVibrio subtilis by ChristianGottfriedEhrenberg,andrenamed Bacillussubtilis by Ferdinand
Cohnin 1872. B. subtilis cellsare typicallyrod-shaped,andare about4-10 micrometers(μm) longand
0.25–1.0 μm in diameter,withacell volume of about4.6fL at stationaryphase. Asothermembersof
the genus Bacillus, itcan forman endospore,tosurvive extremeenvironmentalconditionsof
temperature anddesiccation.
B. subtilis isa facultative anaerobeandhadbeenconsideredasan obligate aerobe until 1998. B.
subtilis isheavily flagellated,whichgivesitthe abilitytomove quicklyinliquids. B.subtilis has proven
highlyamenable to geneticmanipulation,andhasbecome widelyadoptedasa model organism for
laboratorystudies,especiallyof sporulation,whichisasimplifiedexampleof cellulardifferentiation.In
termsof popularityasa laboratorymodel organism, B.subtilis isoftenconsideredasthe Gram-
positive equivalentof Escherichia coli, an extensivelystudied Gram-negative bacterium.
 Habitat:
Thisspeciesis commonlyfoundinthe upperlayersof the soil,andevidence existsthat B.subtilis is
a normal gut commensal inhumans.A 2009 studycomparedthe densityof sporesfoundinsoil (about
106
sporespergram) to thatfoundinhuman feces(about104
sporespergram).The numberof spores
foundinthe humangut was too highto be attributedsolelytoconsumptionthroughfood
contamination.
 Reproduction:
B. subtilis can divide symmetrically tomake twodaughtercells(binaryfission),orasymmetrically,
producinga single endosporethatcanremainviable fordecadesandisresistanttounfavourable
environmental conditions suchasdrought,salinity,extremepH,radiation,andsolvents.The endospore
isformedat timesof nutritional stress,allowingthe organismtopersistinthe environmentuntil
conditionsbecome favourable.Priortothe processof sporulationthe cellsmightbecome motile by
producingflagella,take upDNA fromthe environment,orproduce antibiotics.These responsesare
viewedasattemptstoseekoutnutrientsbyseekingamore favourable environment,enablingthe cell
to make use of newbeneficial geneticmaterial orsimplybykillingof competition.
Under stressful conditions,suchasnutrientdeprivation, B.subtilis undergoesthe process
of sporulation toensure the survivalof the species.Thisprocesshasbeenverywell studiedandhas
servedasa model organismforstudyingsporulation.
 Chromosomal replication:
B. subtilis isa model organismusedtostudybacterial chromosome replication.Replicationof the single
circularchromosome initiatesata single locus,the origin(oriC).Replicationproceedsbidirectionallyand
tworeplicationforks progressinclockwiseandcounterclockwise directionsalongthe chromosome.

3. Chromosome replicationiscompletedwhenthe forksreachthe terminusregion,whichispositioned
opposite tothe originonthe chromosome map.
The terminusregioncontainsseveral shortDNA sequences(Tersites) thatpromote replicationarrest.
Specificproteinsmediateall the stepsinDNA replication.Comparisonbetweenthe proteinsinvolvedin
chromosomal DNA replicationin B.subtilis and inEscherichia coli revealssimilaritiesanddifferences.
Althoughthe basiccomponentspromotinginitiation,elongation,andterminationof replicationare well-
conserved,some importantdifferencescanbe found(suchasone bacteriummissingproteinsessential
inthe other).These differencesunderline the diversityinthe mechanismsandstrategiesthatvarious
bacterial specieshave adoptedtocarry out the duplicationof theirgenomes.
 Genome:
B. subtilis has about4,100 genes.Of these, only192 were showntobe indispensable;another79were
predictedtobe essential,aswell.A vastmajorityof essential geneswere categorizedinrelativelyfew
domainsof cell metabolism,withabouthalf involvedininformationprocessing,one-fifthinvolvedinthe
synthesisof cell envelope andthe determinationof cell shape anddivision,andone-tenthrelatedtocell
energetics.
The complete genome sequenceof B.subtilis sub-strainQB928 has 4,146,839 DNA base pairsand 4,292
genes.The QB928 strain is widelyusedingeneticstudiesdue tothe presence of variousmarkers
[aroI(aroK)906purE1 dal(alrA)1trpC2].
Several noncodingRNAshave beencharacterizedinthe B.subtilis genome in2009, including Bsr
RNAsMicroarray-basedcomparative genomicanalyseshave revealedthat B.subtilis membersshow
considerable genomicdiversity.
 Transformation:
Natural bacterial transformation involvesthe transferof DNA fromone bacteriumto anotherthroughthe
surroundingmedium.In B.subtilis,lengthof transferredDNA isgreaterthan1271 kb (more than1
millionbases).The transferredDNA islikelydouble-strandedDNA andisoftenmore thana third of the
total chromosome lengthof 4215 kb.Itappearsthat about7-9% of the recipientcellstake upanentire
chromosome.
In orderfor a recipientbacteriumto bind,take upexogenousDNA fromanotherbacteriumof the same
speciesandrecombine itintoitschromosome,itmustenteraspecial physiological state
called competence.Competence in B.subtilis isinducedtowardthe endof logarithmicgrowth,especially
underconditionsof amino-acidlimitation.
Under these stressfulconditionsof semistarvation,cellstypicallyhave justone copyof their
chromosome andlikelyhave increasedDNA damage.Totestwhethertransformationisanadaptive
functionforB.subtilis to repairits DNA damage,experimentswere conductedusingUV lightasthe
damaging agent.[18][19][20] These experimentsledtothe conclusionthatcompetence,withuptakeof

4. DNA,isspecificallyinducedbyDNA-damagingconditions,andthattransformationfunctionsasaprocess
for recombinational repairof DNA damage
 ApplicationtoBiotechnology:
Bacillusorganisms,isolatedbysoil sprinkletechnique,are responsible forproducingantibiotics.The
mostantibioticactivitywasseenin Bacillussubtilis MH-4. The most optimal activityoccursat a
temperature of 37 degreesCelsiusandabasic pH of 8. Glycerol isthe optimal carbonsource and L-
glutamicacidis the optimal source of nitrogen.
The antibioticbacitracinwasdeterminedtobe affective onGram-positivebacteriaonly(Jamil 2007).
Otherantibioticsthat Bacillussubtilis formare polymyxin,difficidin,subtilin,andmycobacillin.Polymyxin
isaffective againstGram-negative bacteria,whereasdifficidinhasabroaderspectrum(Todar).
Bacillus subtilis bacteriasecrete enzymes,"suchasamylase,protease,pullulanase,chitinase,xylanase,
lipase,amongothers.These enzymesare producedcommerciallyandthisenzymeproduction
representsabout60%of the commerciallyproducedindustrial enzymes.
 Serious infections caused by Bacillus species:
Thirty-eightpatientswithseriousinfectionscausedbyorganismsbelongingtothe genusBacillusare
described.Ourexperience,andthatreportedinthe literature,indicatesthat,inmostcases,isolated
Bacillusbacteremiaisnota particularlyseriousdisease.Therefore,undermostcircumstances,empiric
antibiotictherapydesignedspecificallyfortreatmentof Bacillusisprobablynotnecessary.Endocarditis
can occur, but apparentlyfollowsbacteremiaonlyinfrequently.Whenthesebacteriacause localized
infectionsuchaspneumonia,pan-ophthalmitis,visceral abscess,ormusculoskeletal infections,tissue
necrosis andprofoundmorbidityare the rule.
The frequencyof these complicationsfollowingbacteremiaappearstobe low but cannotbe estimated
fromour experience orthatreportedinthe literature reviewed.The role of intravasculardevicesand
trauma as predisposingfactorsisemphasized.Immunocompromisedhostsandintravenousdrug
abusersappearpredisposed,butintravasculardevicesinthe formergroupmayplayan importantrole in
the pathogenesisof Bacillusinfections.Antibioticswhichappearespecially useful inthe treatmentof
Bacillusinfectionsare clindamycinandvancomycin,towhichthe vastmajorityof strainsare susceptible
invitro.Beta-lactamantibiotics,includingthe new cephalosporinsandpenicillins,are of little value in
thissetting.
 Clinical spectrum of infection due to Bacillus species:
BacillusspeciesotherthanB anthraciswere isolatedfromculture material andseenongram-stained
smearin 12 patientsovera6 yearperiodina hospital forpatientswithneoplasticdiseases.Insome
casesBacillusspecieswere recoveredrepeatedlyfromanindividual patient,occasionallyfrommore
than one site.Pulmonaryanddisseminatedinfectiondevelopedintwopatientswithacute leukemia
whowere underintensive chemotherapy,andtheydiedfollowingrupture of abrain abscessintothe
ventricularsystem.

5. In bothpatients,Bacillusspecieswere recoveredfromculturesof bloodandsputumantemortem, and
inthe heart'sbloodafterdeath,andseeninhistopathologicsectionsof the lungandbrain.These cases
were similartothose fewpreviouslyreportedcasesinthatthe usuallynonpathogenicBacillus
disseminatedinanimmunologicallycompromisedhost.
Nearlyall the remainingisolateswere fromdrainage fromrecentsurgical wounds.Rarelywasspecific
treatmentgivenforthe Bacillus,andtheyseemedtoexertnodefinite influence onthe patient'sclinical
course,althoughoccasionallythe characterof a wounddrainage alteredafterthe Bacilluswasnolonger
recoveredonculture.
 An Antibiotic from Bacillus subtilis Active against Pathogenic Fungi
Antibioticname = Bacillomycin
A strainof Bacillus subtilis hasbeenisolatedwhichelaboratesapreviouslyundescribedantibiotic
“Bacillomycin.”Thisantibioticpossessesstrikingantifungal activityandalmostcompletelackof
antibacterial action.The fungusspectrumof “Bacillomycin”includespracticallyall of the important
dermatophytesandsystemicfungi.A satisfactorybioassayemployingthe agarcupplate technicand a
spore suspensionof Trichophyton mentagrophytes isdescribed.Some physical andchemical properties
of the antibioticare giventogetherwithasimple procedure foritsconcentrationfromc.
Environmental and Industrial Use of Bacillus Subtilis:
Presentinthe environmentinthe air,soil andwater,Bacillussubtilisisabacteriumthatisgenerally
harmlesstohumans.It does,however,have anenviable abilitytoproduce enzymesthatmankindhas
harnessedforindustry.The speciescanalsobreak downvariousnaturally-occurringpollutants,whichis
useful forenvironmental purposes,andhasadditional usesasapesticide.The valueof microbeslikeB.
subtilistoindustryisthatcultivatingthemonalarge scale to produce enzymesandothersubstances
tendsto be cheapand relativelyuncomplicated.
 Cleaning Agents
Some industriesuse Bacillussubtilistoproduce enzymesthatare useful inthe cleaningindustry.For
example,the speciescanproduce proteases,whichare enzymesthatbreakdownprotein.These
proteasesare an ingredientinsome washingdetergentsandcanalsobe usedinthe leatherindustryto
breakdownunwantedsubstancesonskins.
 Paper and Textile Industries
Amylases,whichbreakdownstarch, are some otheruseful enzymesthatB.subtiliscanproduce inbulk.
Starch breakdownisa useful stepinthe productionof paperandinthe treatmentof textiles.
 Pollution Treatment
The practice of usingspecieslike B.subtilistobreakdownpollutantsiscalledbioremediation.The
bacteriumcan actuallyeatup lightfractionsof crude oil like paraffinandconvertthemintoless
environmentallyharmfulsubstances.B.subtiliscanalsoproduce a surfactant,whichhelpstodisperse

6. crude oil,and the enzymesthatitcan produce include lipases,whichcanbe turnedintobioremediants
for fat-richpollutantslike sewage andotherwaste water.
 Pesticide Industry
Certainbacterial speciescaninterfere withthe abilityof pathogenstoattackcrops. A strainof B. subtilis
calledQST713 isable to triggera strong resistance toattack byfungi incrops that have beentreated
withit.The bacteriumcanalsocombat the potentiallyinfectiousfungi byvariousmechanisms,suchas
directcompetitionfornutrients.
 Food Industry
As Bacillussubtilisproducesalotof enzymesthatare valuable infermentation,the speciesisindemand
for certainfoodprocessingindustries.Anadditional pointinB.subtilis'sfavoristhatthe bacteriumis
classedbythe U.S. Foodand Drug Administrationas"GenerallyRegardedasSafe"or"GRAS,"which
meansitis regardedassafe for consumerstoeat.An example of aBacillussubtilis-fermentedfoodis
natto,a soybeanproductpopularinJapan.
References:
 Shylakhovenko, V.A. (June 2003). "Anticancer and Immunostimulatoryeffects of NucleoproteinFraction of Bacillus
subtilis". Experimental Oncology 25: 119–123.
 Clancy, Paul (Jun 23, 2005). Looking for Life, Searching the Solar System. Cambridge UniversityPress.[
 Horneck, G.; Klaus, D. M.; Mancinelli, R. L. (2010). "Space Microbiology".Microbiologyand Molecular Biology
Reviews 74 (1): 121–56.
 Ehrenberg CG (1835). Physikalische Abhandlungen der Koeniglichen Akademie der Wissenschaften zu Berlin aus
den Jahren 1833–1835. pp. 145–336.
Date: 18/10/2015