Salt Stress Tolerant Genes In Halophilic And Halotolerant .
Int.J.Curr.Microbiol.App.Sci (2015) 4(1): 642-658ISSN: 2319-7706 Volume 4 Number 1 (2015) pp. 642-658http://www.ijcmas.comOriginal Research ArticleSalt stress tolerant genes in halophilic and halotolerant bacteria: Paradigmfor salt stress adaptation and osmoprotectionPriyanka Das1,2, Bijay Kumar Behera1, Dharmendra Kumar Meena1*, Syed Afrin Azmi2,Soumendranath Chatterjee2, Kanti Meena3 and Anil Prakash Sharma11Central Inland Fisheries Research Institute, Barrackpore, Kolkata,West Bengal, India -7001202Parasitology and Microbiology laboratory, Department of Zoology,University of Burdwan, Burdwan, West Bengal, India3Central Research Institute for Jute and Allied Fibres, Barrackpore,Kolkata, West Bengal, India -700120*Corresponding alotolerant,Halophilic,Osmoregulation,Salt stresstolerant genesSalinity stress is one of the major factors negatively affecting growth andproductivity in living organisms including plants and bacteria resulting insignificant losses worldwide. Therefore, it would be fruitful to develop salinitystress tolerant useful species and also to understand the mechanism of stresstolerance that simulate the production of bioactive osmotic compatible solute whichare of great significance to cope with hostile salt stress conditions, and to haveindustrial and pharmaceuticals applications as well. A prerequisite for molecularstudies is the identification of genes involved in the accumulation of compatiblesolutes. In this back drop, this review highlights various studies investigating saltstress tolerant genes from different halophilic / halotolerant bacteria, focusing onrecent developments in this area.Introductionbiotechnology tools and technique, it hasbeen possible to access genes from diversebiological systems and deploy them in targetspecies. Use of crystal protein gene fromthe soil bacterium Bacillus thuringiensis ingenetic engineering of crops like cotton,clearlydepicts,howgenesfromevolutionarily distant organisms can bringnew revolution in agricultural production(Jenkins et al., 1991). Therefore, it isimperative to explore the elite andThe damaging effects of salt accumulationin agricultural soils have influenced ancientand modern civilizations. It is estimated that20% of the irrigated land in the world ispresently affected by salinity (Yeo, 1999).Identification of beneficial traits and theiruse in agriculture and applied sciences basedon discovery and use of novel genes hasbeen the key element in meeting the targetof food security and sustainability of thefood production. With the advent of new642
Int.J.Curr.Microbiol.App.Sci (2015) 4(1): 642-658meticulous type of organism includingmicrobes which are having important genesfor enhancing the agricultural production.cereus, and it was observed that they couldsurvive up to 20% salt concentration(Behera et al., 2013a, b) (Gene Bankaccession #JZ198969-JZ199140), and thatwas further confirmed with 16 s rRNA andwhole genome transcriptome profiling isperformed to unwound the real ofquestionable remarks. Similarly, Behera etal. (2014a) screened the bacterial isolatescollected from east coast of India andsuggested that most of them belong toFirmicutes and Proteobacteria group whichmight be of great interest from prospectingnovel and candidate salt stress tolerant genes(Behera et al., 2014a). Recently, Behera etal. (2014b) has reported a bacteriaHalomonas salina strain CIFRI1 that couldsurvive up to 20% of salt ry survival in face of extremesalt concentration as function of eitherevolutionary progression or direct nuclearlevel modification in bacterial genome dueto salt stress tolerance genes.OsmoregulationOsmoregulation is the active regulation ofthe osmotic pressure of an organism's fluidsto maintain the homeostasis of theorganism's water content to keep theorganism's fluids from becoming too dilutedor too concentrated (Solomon et al., 2002).During the course of time osmoconfirmationhas evolved a fundamental phenomenonexhibited by bacteria, to uphold the osmoticbalance between cellular fluids and externalenvironment (Wood, 2011). With the paceof time microorganisms have continue todevelop a complex stress tolerance system tosurvive with the changes in their externalenvironment. As a result of alteration totheir environment, many extremophilicmicroorganisms have evolved uniqueproperties of considerable biotechnologicaland commercial significance. Halophilic orhalotolerant eubacteria are characterized bya much greater metabolic diversity(Margesin and Schinner, 2001). As theirintracellular salt concentration is low, theymaintain an osmotic balance of theircytoplasm with the external medium byaccumulating high concentrations of variousorganic osmotic solutes.Compatible solutesCompatible solutes are osmotically active,low molecular weight substances, highlywater-soluble sugars or sugar alcohols, otheralcohols, amino acids, or their derivativesthat make halophilic bacteria versatile intheir adaptation to salinity (Ventosa et al.,1998). Compatible solutes keep away thecells from plasmolysis during adverse saltstress arbitrated environmental conditions(Kempf and Bremer, 1998). Compatiblesolutes exert their effect through changes insolvent structure and/or subtle changes inthe dynamic properties of the protein ratherthan by changing the structure of the l applications as stabilizersof biomolecules i.e. enzymes, DNA,membranes and whole cells, salt antagonists,stress-protective agents, increase freshnessMany marine organisms are slighthalophiles (with 3% w/v NaCl in sea water).Moderate halophiles optimally grow at 315% w/v NaCl; extreme halophiles at 25%w/v NaCl (halobacteria and halococci) andborderline extreme halophiles require atleast 12% w/v salt (Kushner and Kamekura,1988). Behera et al. (2012) identified andcharacterizedbacteriaStaphylococcusepidermidis, (P-30) and tested itssurvivability in response to varyingconcentration of NaCl along with Bacillus643
Int.J.Curr.Microbiol.App.Sci (2015) 4(1): 642-658of foods by stabilizing components andinduction of osmolytes in cells can increaseprotein folding and thereby improve salttolerance which could be useful inagriculture and xeriscaping (Roberts, 2005;Detkova and Boltyanskaya, 2007).(Oren, 2010). Ectoines also find applicationsin the treatment of the mucous membranesof the eye. Ophthalmologic preparationscontaining these molecules are useful foreye treatment to decrease the drynesssyndrome. Moreover, (Detkova andBoltyanskaya, 2007) reported that ectoine isused as components of shampoo, for oralcare and as adjuvants for vaccines.EctoineOne of the most abundant osmolytes innature is ectoine which are common inaerobic heterotrophic Eubacteria (Galinski,1995). It was first discovered in tothiorhodospirahalochloris (Galinski et al., 1985) but later agreat variety of halophilic and halotolerantbacteria were found to produce thiscompound, often together with its 5-hydroxyderivative (Rothschild and Mancinelli,2001). For instance, Halomonas elongata,an extremely halotolerant bacteria had beenreportedtoproduceectoineandhydroxyectoines whose relative proportiondepends on salinity and temperature(Margesin and Schinner, 2001). Ectoinesynthesis is carried out by the products ofthree genes: ectABC (Ofer et al., 2012) (Fig.1 and 2). The ectA gene codes fordiaminobutyric acid acetyltransferase; ectBcodes for the diaminobutyric acidaminotransferase and ectC codes for ectoinesynthase (Roberts, 2005).TrehaloseTrehalose, is a non-reducing glucosedisaccharide synthesized by otsA and otsBgene, occurs in a wide variety of organisms,from bacteria and archaea to fungi, plantsand invertebrates (Elbein et al., 2003).Trehalose was found to constitute the shellsthat are secreted by various insectspositioned on tree leaves in the Middle East(Richards et al., 2002).Trehalose plays a crucial role in metabolichomeostasis and abiotic stress tolerance invarious organisms (Turan et al., 2012).Trehalose also presents in several commonfoodstuffs such as bread, wine, beer,vinegar, and honey. Trehalose has severalunique properties as a stress metabolitewhichincludeshighhydrophilicity,chemical stability, nonhygroscopic glassformation and no internal hydrogen bondformation. In prokaryotes like bacteriatrehalose can be used as an external carbonsource as it is frequently used as acompatible solute to compete with osmoticstress(Arguelles,2000).Moreover,trehalose is not only useful as acryoprotectant for the freeze drying ofbiomolecules, but also for long-termconservation of microorganisms, as themembrane structure is preserved in thepresence of this disaccharide (Empadinhasand da Costa, 2008) The biosyntheticpathway of trehalose in Escherichia coli isrepresented in Figure 3.Ectoines as well as other compatible soluteshave been found to improve protein foldingand to protect biomolecules such asenzymes, nucleic acids, antibodies and evenwhole cells against heating, freeze-thawing,drying or chemical treatment (Barth et al.,2000). Industrial and general application ofectoine keeps on increasing day by day:used in dermopharmacy as anti-ageingagents in skin creams, inhibits aggregationof Alzheimer s disease and recently, aclinical trial was initiated to test its efficacyin inhalations against bronchial asthma644
Int.J.Curr.Microbiol.App.Sci (2015) 4(1): 642-658involved in cell functioning whose extremehigh or low concentrations inhibit thephysiological activities of cells (Padan et al.,2001). Different mechanisms are adopted bythe cells for maintaining the homeoticbalance which includes enhancement of K uptake, elimination of surplus Na , reallocation of Na into other intracellularcompartments (such as vacuoles), andbiosynthesis of compatible solutes in thecytoplasm to maintain osmotic equilibrium.In prokaryotes, there are five classes ofNa /H antiporters such as NhaA, NhaB,NhaC, NhaD, and NapA (Krulwich et al.,2009). Among all of them NhaA is the mostextensively studied Na /H antiporter inboth the plasma lemma and tonoplast of E.coli which plays a major role in maintainingcell pH and Na homeostasis (Volkmar etal., 1998).Glycine betaineCholine oxidase is an important enzymewhich accumulates to high levels in thecytoplasm of cells to prohibit dehydrationand plasmolysis in adverse hyperosmoticenvironments (Kempf and Bremer, 1998;Wani et al., 2013). Glycine betaine (N, N,N-trimethyl glycine) is a quaternaryammonium compound found in ates,plantsandmammalssynthesized by choline oxidase (Chen andMurata, 2008; Turan et al., 2012). First genecluster encoding a primary ABC-typetransporter for the compatible solute glycinebetaine in Methanosarcina, a methanogensspecies has reported (Roessler, 2002).Corollary, N -acetyl- -lysine might besynthesized from lysine by the action of twoenzymes, a lysine-2, 3-aminomutase (ablA)and a lysine acetyl transferase (ablB)(Robertson, 1992) (Fig. 4). Two secondarycarriers for the uptake of glycine betaine Nacoupled system which has high-affinitycoded by the gene BetP and EctP whichprefers ectoine to glycine betaine have beenreported (Peter, 1998; Boscari et al., 2002).Production of extracellular proteaseProteases constitute one of the mostimportant groups of industrial enzymes withversatile applications including meattenderization, detergents, cheese-making,de-hairing, baking, waste management andsilver recovery (Akcan and Uyar, 2011).Recently, there has been an increasedinterest in proteases as targets fordeveloping therapeutic agents (Maryanoff,2004). According to the market researchreport on world enzymes published in 2007,the world market for enzymes is expected togrow 7.6% per year to 6 billion in 2011(David et al., 2009). Microbial proteasesaccount for approximately 60% of the totalenzyme sales in the world (Banik andPrakash, 2004). One of the severalchallenges faced by industrial application ofmicrobial proteases is optimal activity andstability in a wide range of salinity.Moreover, halophilic proteases are lesssuitable for saline fermentation processes,because they need at least 12.5% (w/v) NaClfor expression of high activities (Ventosa ifiedinvariousmicroorganism, has been reported (Boscariet al., 2002) for instance BetP and EctP areclosely related to glycine betaine transporterOpuD from B. subtilis; the cholinetransporter BetT and the carnitinetransporter CaiT from E. coli; the glycinebetaine transporter BetL from Listeriamonocytogenes (Sleator and Hill, 2002), andtheputativeBetPproteinsfromMycobacterium tuberculosis (Philipp et al.,1996) and from Haemophilus influenzae(Fleischmann et al., 1995).Na and H antiportersNa and H ions are most commonly645
Int.J.Curr.Microbiol.App.Sci (2015) 4(1): 642-658al., 1998). However, halotolerant proteasesare active at both low and highconcentrations of NaCl. Inherent capabilityof halotolerant bacteria to grow over anextended range of salt concentrations (330% NaCl, w/v) put forward them ascandidate for bio-prospecting than theirhalophilic counterparts, as they need at least12.5% (w/v) NaCl for expression of highactivities (Ventosa et al., 1998). Moreover,marine halotolerant microorganisms showwider distribution, distinct physiologicalcharacteristics and nutrient utilization ascompared to their terrestrial counterpartsand obligate halophiles (Barindra et al.,2006). Most of the Gram-positive or Gramvariable, endospore forming rods withhalotolerant properties has been assigned tothe genus Bacillus (Yoon et al., 2003).Bacillus sp. grows in a pH range of 7.0 11.0and produces extracellular protease andalkaline proteases (Romero, 2007). With thisin view, the present investigation treatshalotolerant bacteria as a potential source ofenzymes (Table 1).system to mediate nutrient uptake bybinding to nutrients with high affinity priorto translocation. Moreover, Chen et al.(2001) also ascertained MBP whichstimulates the ATPase activity of themembrane-associatedporterthroughtransmembrane subunits viz. MalF andMalG and two copies of the ATP bindingsubunit MalK.Agricultural significance of salt stresstolerant bacterial genes in salt stressmitigationCurrently, more than 800 million hectares ofland throughout the world are affected bylevels of salt that could substantially reducecrop productivity (Munns and Tester, 2008).Strategies for alleviation of salt stressinvolve developing salt-resistant cultivars,leaching excess soluble salts from upper tolower soil depths, flushing soils that containsoil crusts at the surface, reducing salt byharvesting salt-accumulating aerial plantparts in areas with negligible irrigation wateror rainfall for leaching, and amelioration ofsaline soils under cropping and leaching(Bacilio et al., 2004). An alternative is toalleviate salt stress by inoculating crop seedsand seedlings with plant growth promotingbacteria (PGPB). Beneficial effect of PGPBunder salinity has been related to ring toxic Na ions, tic activities (Dodd and PerezAlfocea, 2012). Several studies have beenaccomplished to improve salt tolerance byintroducing salt resistant bacterial gene inagriculturally important crop that has beensummaries in Table 3 and agriculturallyimportant bacteria have been enumerated inTable 2.ABC transport cycle through ATPbinding cassette dimerABC transporters are transmembraneproteins with representatives in all extantphyla from prokaryotes to humans (PonteSucre, 2009), that utilize the energy ofadenosine triphosphate (ATP) hydrolysis tocarry out certain biological processesincluding translocation of various substratesacross membranes and non-transport-relatedprocesses such as translation of RNA andDNA repair (Davidson et al., 2008). In lastdecade, researcher have discovered varioussub-family of ABC transporters in bacteria,for instance, Boos and Lucht (1996)reported periplasmic maltose binding protein(MBP) which constitutes maltose transport646
Int.J.Curr.Microbiol.App.Sci (2015) 4(1): 642-658Table.1 Proteases secreted by bacteriaSr Source species/no. strain of bacteria1.Bacillus aquimarisstrain VITP4Nature of sourcebacteria /proteasessecretedHalotolerant / Extracellular2.VirgibacillusDokdonesis Vitp14Halotolerant/ Extracellular5 mM CTAB /1.5 M;NaCl, CaCl2, MgCl2,CuSO4enhanced the activity7.0 and40 C.3.Bacillus sp.Alkalophilic/Alkaline proteaseHigh alkaline conditions11 and 60 C.4.Bacillus subtilisAP-MSU 6Cu2 , Hg2 , Mn2 andBa2 / 0.5 M9.0 and40 C3 to 15% NaCl100mMAlkaline pH5.6.7.8.9.10.Moderatelyhalophilic/alkalineserine proteaseSinorhizobium sp.Halophilic /strain BL3ATPase,Pseudoalteromonas ModeratelyHalophilic/ruthenicaHaloprotease CPIBacillus clausii IHalotolerant/52Oxidant and SDSstable alkalineproteaseBacillus sp. HS-4Halophilic/ExtracellularAlkaline ProteaseBacillus halodurans Haloalkaline /CAS6ExtracellularAlkaline ProteaseBacillus horikoshii Haloalkaline/alkaline protease11.Salinivibrio sp.strain AF-200412.Salinivibrio sp.strain ineproteaseModeratelyhalophilic/Conducive medium/salt concentrationBasal Zobell medium/0 4MOptimumpH andtemperature7.5 and37 CReferencesShivanandandJayaraman,2009Rajeswariet al., 2012Genckaland Tari,2006Maruthiahet al., 2013Sa nchezPorro et al.,2009Joo andChang,20050.4% (w/v) NaCl11.0 and 45 CCa2 and Mg2 ions8 and 37 C30% NaCl9.0 and50 C2% maltose, 1% sodiumcitrate, 0.8% NaCl, and0.6% sodium carbonateto the culturing medium0 0.5 M NaCl;9 and 37 CJoo andChoi, 20128.5 and65 C,KarbalaeiHeidari etal., 20077.5 to 10% (w/v) sodium 9.0 andsulfate or 3% (w/v)32 C647Shama andHameed,2011Annamalaiet al., 2013Amoozegaret al., 2007
Int.J.Curr.Microbiol.App.Sci (2015) 4(1): 642-65813.Halobacilluskarajensis strainMA-2.14.Bacillus subtilisRSKK9615.Bacillus subtilisRSKK9616.Bacillus remelyhalotolerant/extracellularalkaline erant /serine alkalineproteaseHalotolerant/thermostable -AmylaseHaloloterant / alphaamylasesodium acetate(4.6 U ml 1)55% and 50% NaClactivity and gelatin8.0-8.5 and34 CKarbalaeiHeidari etal., 2009Salts FeSO4.7H2O andMgSO4.7H2O wasfound to increaseprotease productionFeSO4, ZnSO4 andCuSO4 inhibitedbacterial growth as aresult, amylaseproductionSoybean meal9.0Akcan andUyar, 201137 CAckan andUyar, 20119.5 and 60 CSaurabh etal., 20070.5% tryptophan inproduction mediumenhanced the enzymeproductivity to two foldMaltose, glucose,lactose and solublestarch weresupplemented as carbonsources.7.5 and 70 CRasooli etal., 20087 and 70 CZar et al.,2013Fig.1 Biosynthetic pathway of ectoine in Bacillus halodurans. The genes ectB, ectA and ectCencode aminotransferase, acetyltransferase and ectoine synthase respectivelyL-aspertate-semialdehydeEctB aminotransferaseL-2, 4- diaminobutyrateEctA acetyltransferaseN- acetyl -L- 2, 4 - diaminobutyrateEctC ectoine synthaseEctoine(2 methyl 1,4,5,6tetrahyddropyrimidine6484carboxylic acid)
Int.J.Curr.Microbiol.App.Sci (2015) 4(1): 642-658Table.2 Agriculturally important bacteria and affected cropsSrno1.Name of bacteria2.Brevibacteriumepidermidis RS15,Micrococcusyunnanensis RS222,and Bacillusaryabhattai RS341Escherichia coli.Coastal Soil4.Brevibacteriumiodinum, Bacilluslicheniformis andZhihengliuela albaCoastal soil5.Rhizobia and plantgrowth-promotingrhizobacteria e6.Bacillus and Bacillusderived genera7.Mannitol 1-phosphatedehydrogenase (mtlD)gene producing bacteriaArthrobacterglobiformis3.8.Hallobacillus sp. SL3and Bacillushalodenitrificans PU62IsolatedmediumSaline habitatsMitigatedcropWheatseedling
the soil bacterium Bacillus thuringiensis in genetic engineering of crops like cotton, clearly depicts, how genes from evolutionarily distant organisms can bring new revolution in agricultural production (Jenkins et al., 1991). Therefore, it is imperative to explore the elite and ISSN: 2319-7706 Volume 4 Number 1 (2015) pp. 642-658
Stress genes were selected whose expression level change was twofold under drought conditions. The 143 non-stress genes were selected on the basis of their expression level change being between 0.33. Eight other O. sativa genes were selected because they were shown to be induced by abiotic stress (cold, drought, osmotic stress) in our other .
A large number of abiotic stress responsive genes have been reported in a variety of plants including rice and Arabidopsis. These genes induced during stress condi- . (Salt ) Regulation of adaptive stress response and plant fertility (Zou et al. 2008) OsbZIP23 Drought , Salt Regulation of expression of genes involved in stress .
The salt tolerant plants are divided into lists by salt tolerance, plant characteristics, and groups associated by light and moisture requirements. This manual is a tool for RIDOT landscape and engineering personnel to help select plants for roadside use in Rhode Island. 17. Key Words Salt, salt tolerance, planting guide, roadside plants 18.
relationship among the CUB of abiotic stress and CUB of housekeeping genes, irrespective of the plant species. These result represents that plant may be planned for the abiotic stress resistance by the process of optimizing of codons. While the genes that show similarity by less than 50%, proposes the independency of abiotic stress genes
stress tolerance towards drought, cold, heavy metal, osmotic and salt stress tolerance in rice and other plant species [11-16]. At the molecular level, abiotic stress tolerance is known to induce several genes in plants, and most of these genes are linked to SA-dependent activation. These genes include chaperones, antioxidants, secondary .
(A), Gossypium hirsutum L. JGI (AD1) and Gossypium barbadebse L. NAU (AD2) to Arabidopsis thaliana. Using DNA demethylase genes sequence of Arabidopsis as reference, 25 DNA demethylase genes were identified in cotton by BLAST analysis. There are 4 genes in the genome D, 5 genes in the genome A, 10 genes in the genome AD1, and 6 genes in the .
32 genes responsible for autosomal recessive nonsyn-dromic hearing loss (DFNB), 8 genes responsible for both DFNA and DFNB, one gene responsible for auditory neuropathy, 3 genes responsible for X-linked hearing loss, and 23 genes responsible for syndromic hearing loss. A list of the targeted genes responsible for nonsyndromic
1.4 importance of human resource management 1.5 stress management 1.6 what is stress? 1.7 history of stress 1.8 stressors 1.9 causes of stress 1.10 four major types of stress 1.11 symptoms of stress 1.12 coping with stress at work place 1.13 role of human resource manager with regard to stress management 1.14 stress in the garment sector
