title: Genetic and phenotypic diversity of plant growth promoting rhizobacteria isolated from sugarcane plants growing in pakistan.
abstract: Bacteria were isolated from roots of sugarcane varieties grown in the fields of Punjab. They were identified by using API20E/NE bacterial identification kits and from sequences of 16S rRNA and amplicons of the cpn60 gene. The majority of bacteria were found to belong to the genera of Enterobacter, Pseudomonas, and Klebsiella, but members of genera Azospirillum, Rhizobium, Rahnella, Delftia, Caulobacter, Pannonibacter, Xanthomonas, and Stenotrophomonas were also found. The community, however, was dominated by members of the Pseudomonadaceae and Enterobacteriaceae, as representatives of these genera were found in samples from every variety and location examined. All isolates were tested for the presence of five enzymes and seven factors known to be associated with plant growth promotion. Ten isolates showed lipase activity and eight were positive for protease activity. Cellulase, chitinase, and pectinase were not detected in any strain. Nine strains showed nitrogen fixing ability (acetylene reduction assay) and 26 were capable of solubilizing phosphate. In the presence of 100 mg/l tryptophan, all strains except one produced indole acetic acid in the growth medium. All isolates were positive for ACC deaminase activity. Six strains produced homoserine lactones and three produced HCN and hexamate type siderophores. One isolate was capable of inhibiting the growth of 24 pathogenic fungal strains of Colletotrichum, Fusarium, Pythium, and Rhizoctonia spp. In tests of their abilities to grow under a range of temperature, pH, and NaCl concentrations, all isolates grew well on plates with 3% NaCl and most of them grew well at 4 to 41degrees C and at pH 11.
authors.affiliation: Department of Microbiology and Molecular genetics, University of the Punjab, Lahore 54590, Pakistan. saminamehnaz@yahoo.com
authors.forename: Samina
authors.initials: S
authors.lastname: Mehnaz
authors.forename: Deeba Noreen
authors.initials: DN
authors.lastname: Baig
authors.forename: George
authors.initials: G
authors.lastname: Lazarovits
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism; D015373:Bacterial Typing Techniques; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004798:Enzymes / Q000378:metabolism; D014644:Genetic Variation; D006856:Hydrogen Cyanide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007210:Indoleacetic Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D009586:Nitrogen Fixation; D010154:Pakistan; D010710:Phosphates / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism*; D018517:Plant Roots / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D058441:Rhizosphere; D031786:Saccharum / Q000254:growth & development / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D004798:Enzymes; D007210:Indoleacetic Acids; D010710:Phosphates; D010937:Plant Growth Regulators; D012336:RNA, Ribosomal, 16S; C088386:homoserine lactone; D006856:Hydrogen Cyanide; C030737:indoleacetic acid; D015107:4-Butyrolactone