Isolation and Characterization of Pink Pigmented Facul Tative Methylotrophs From Coleus forskohlii and Their Influence on Growth and Tuber Yield
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Date
2012
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UAS, Dharwad
Abstract
Investigations were carried to isolate Pink Pigmented Facultative
Methylotrophs (PPFM), characterize them and study their beneficial effects on Coleus
forskohlii. Samples of C. forskohlii were collected grown in different villages such as
Nandihalli, Naganahatti, Rajahamsagada, Tarihalli, Hidakal, of Belgaum district,
UAS, Dharwad and UAS, Bangalore (GKVK). As many as fifty isolates were isolated
from these samples on selective AMS medium. The isolates were characterized based
on their morphological and biochemical characteristics. The results revealed that all
the isolates were Gram negative and rod shaped with the dimension ranging from 0.6-
1.0 x 1.0-1.5 μm. The colonies were pink in colour due to pigmentation. The
biochemical characteristics revealed that all the isolates showed positive for oxidase,
urease, citrate and catalase tests. All the isolates utilized glucose, glycerol, tartarate
and acetate.
Further, the isolates were screened for beneficial characters. The results
revealed that the highest indole acetic acid production was recorded in the isolates
PPFM 36 and PPFM 50 (29.97 μg ml-1 of each culture filtrate) and the maximum GA
production (59.13 μg ml-1 of culture filtrate) was by the isolate. The isolates were
also tested for P-solubilization activity, antagonistic activity, siderophore and HCN
production. The maximum Pi release was observed in PPFM 138 (10.07%). None of
the isolates produced HCN and siderophores. And, as many as nineteen isolates
showed antifungal activity against three important fungal pathogens of Coleus namely
Sclerotium rolfsii, Fusarium oxysporum and Rhizoctonia bataticola. Based on these
beneficial characters, three efficient PPFM isolates were selected for the pot culture
experiment. The results have revealed that all the PPFM isolates performed better
than the reference strain (Methylobacterium extorquens) and uninoculated control.
The isolate PPFM 50 isolated from Nandihalli village was most promising which
recorded significantly higher growth and tuber yield parameters of C. forskohlii
followed by PPFM 32.
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Agribusiness Management