Identification and potential enzyme capacity of flavobacteria isolated from the rhizosphere of barley (Hordeum vulgare L.)

Abstract

The diversity of 99 flavobacterium-like isolates from a barley rhizosphere is described. They were identified on 1/10 strength tryptic soy agar by their yellowish colour and a flexirubin reaction after exposure to 10% KOH.16S rDNA partial sequencing identified the majority (70%) of isolates as Flavobacterium. Twelve percent of the isolates belonged to other genera in the phylum Bacteroidetes. Finally 17% of the isolates did not belong to the phylum Bacteroidetes. Most of the Flavobacterium isolates were affiliated to various aquatic, validly named species and likely represent a bulk of undescribed soil Flavobacterium species found in especially high numbers in the rhizosphere of young plant roots. Most Flavobacterium isolates showed gliding motility on CY agar and VY/2 agar, whereas none of the other isolates shared this feature. A high percentage of Flavobacterium strains produced enzymes involved in polysaccharide and protein digestion as well as extracellular phosphatases, compared with strains related to other genera in the phylum Bacteroidetes.