title: A simple method to isolate biofilm-forming Bacillus subtilis and related species from plant roots.
abstract: A novel method was developed to isolate pure cultures of wild-type Bacillus subtilis and related species from plant roots, even roots washed free of adhering soil. The method uses casein digest-mannitol agarose (CM) media that promote rapid dendritic growth (low K+ ion) or profuse surface film formation (high K+ ion) of Bacillus species at 40 degrees C. Inoculation from the tips of surface growth on agarose leads to self-purification and streaking on CM agar plates (hard agar and high K+) leads to characteristic colony morphology. Phenotypic and 16S rDNA analysis revealed that most root isolates obtained by this method are spore-forming Bacillus species, with enrichment for B. subtilis and its close relatives. Of particular interest is the finding that the majority of these Bacillus isolates and the B. subtilis Marburg strain also form adhering biofilms on inert surfaces. Thus the methods presented may be useful in isolation of biofilm-forming Bacillus and investigation of their role on plant roots.
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA. fall@colorado.edu
authors.forename: Ray
authors.initials: R
authors.lastname: Fall
authors.forename: Rebecca F
authors.initials: RF
authors.lastname: Kinsinger
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Wheeler
mesh_terms: D001412:Bacillus subtilis / Q000145:classification* / Q000254:growth & development / Q000302:isolation & purification*; D001422:Bacterial Adhesion; D015373:Bacterial Typing Techniques; D001431:Bacteriological Techniques; D018441:Biofilms / Q000254:growth & development*; D002364:Caseins / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D004275:DNA, Ribosomal / Q000737:chemistry / Q000302:isolation & purification; D020459:Genes, rRNA; D008353:Mannitol / Q000378:metabolism; D008969:Molecular Sequence Data; D010641:Phenotype; D018517:Plant Roots / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013171:Spores, Bacterial / Q000166:cytology / Q000254:growth & development; D013696:Temperature
chemical_list: D002364:Caseins; D003470:Culture Media; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D008353:Mannitol; C475729:casein hydrolysate