ICRISAT Archival Report 2006 - The seedlings of success in the ...

Milestone: Botanicals with ability to kill insects having compatibility with entomopathogenic microorganisms
identified and appropriate delivery systems developed (OPR/GVRR) 2008
Characterization of bacterial isolates for multiple traits: Ensuring a healthy crop is a first step towards protecting
it from insect pests and diseases. Microorganisms can play a vital role in promoting plant growth, managing insectpests,
and maintaining soil health. Keeping this in view, bacteria from habitats such as composts and soil, having at
least one beneficial trait and found highly promising in previous studies, were evaluated again to see if a given strain
had more than one beneficial trait. Of the 14 isolates studied, four (HIB 67, SB 24, SB 26, and SRI 77) produced
crystalline parasporal bodies, three (EB 13, BWB 21, and SB 21) were positive for siderophore production, two (EB
13 and SB 21) solubilized Rock Phosphate, eight (BCB19, BWB21, EB 13, HIB67, SB9, SB21, SB24, and SB26)
were antagonistic to Macrophomina phaseolina, and two (BWB 21 and SRI 360) were compatible with
Metarrhizium anisopliae - a fungus pathogenic to Helicoverpa armigera. In antagonistic studies with M. phaseolina,
maximum zone of inhibition was recorded with EB 13 (17 mm diameter), followed by BCB 19 (12 mm). Range of
inhibition zone was 5 - 17 mm diameter on culture medium. Insect killing ability of these isolates was studied by
releasing H. armigera neonates on sprouted chickpea seeds inoculated with the bacterial isolates. Of the nine
isolates, maximum percent mortality was observed with SB 26 (66%), followed by BWB 21, SB 9, SB, 21, and
BCB 19. Market sample of a Bt product from USA showed 74% kill. The plant growth promoting property of these
isolates was studied on pearl millet variety ICM 155 by paper towel method. Four strains (SB9, CP8-3, HIB67, and
SB21) enhanced plant growth at least on par with the reference strain of Azotobacter (HT54), which was 12.6%
superior over the control. Based on the presence of multiple traits and their potential value in crop production, four
bacterial isolates (SB9, SB21, BCB19, and BWB21) were selected for field studies for crop protection in 2006-07.
Strain SB 26 did not get selected despite showing high mortality because it reduced plant growth over the untreated
control.
OP Rupela
Microbial properties of cattle excrement and their fermentation products: Visits to fields of practitioners of
certified organic farming (OF) reporting high yield and apparent high population of natural enemies of insect-pests
prompted this study. Apparent concerns of policy makers and research managers on increased cost of crop
production was to be addressed through the low-cost and biological inputs widely used by OF practitioners. A
fermented broth called Amrit Paani (AP) or Jeevamrut was one such input. Microbial properties of AP and of cow
dung, its major ingredients are presented here. Buffalo dung was included in the studies to learn differences in
excrements of the two bovines. Fresh samples of excrement were collected aseptically and subjected to counting
population of total bacteria, total fungi, total actinomycetes (indicators of soil health), P-solubilizers, Pseudomonas
fluorescens (manager of soil borne diseases), siderophore producers (chellate iron and promote plant growth), and
Escheritia coli (indicator of threat to human health). Data in Table 1 suggest that both cow and buffalo dung had
similar population of total bacteria, total fungi, total actinomycetes, and P. fluorescens. Population size of P-
solubilizers was undetectable in cow dung, but very high in buffalo dung (log 10 6.00 g -1 dry mass) and siderophore
producers were absent in buffalo dung, but high in cow dung (log 10 4.99 g -1 dry mass). Microbiology of AP (applied
to soils along with irrigation water and reported by farmers to improve crop growth) using excrements from the
different bovines was quite revealing. We studied the population of different microorganisms at day 0 and day 3
under two fermentation conditions: a) flasks placed on shaker, and b) stationery culture. Data of day 3 indicated that
microbial population, except actinomycetes and P. fluorescens, grew well in shake culture (Table 1). The counts
were similar irrespective of the source of excrement. P-solubilizers in shake culture of AP of cow dung were about
10 times greater than that of buffalo dung. Noticeably, siderophore population was not detected even at the lowest
dilution (Table 1) suggesting that this group of bacteria do not like aeration. Population of different microorganisms
in stationary cultures was similar in the AP prepared using cow or buffalo dung. The striking difference was in the
population of siderophores, which was high in the AP prepared using cow dung (log 10 3.73 mL -1 ), while it was
absent even at the lowest dilution in buffalo dung (Table 1).
Population of E. coli (which is considered a human health risk if present in consumables) was high in excrements of
both cow and buffalo, and in the AP prepared using these. Since use of cow dung has been widely practiced in India
for centuries for plastering floors of kitchens daily (when kitchens used to be of mud floor, practiced in rural areas
even today), it is likely that Indian population is adapted to E. coli. Presence of high population of E. coli in human
intestines (about one million per g excrement) is a normal phenomenon, where they are an important source of
Vitamin K (absorbed through intestines). Rarely a strain of this bacterium is pathogenic to humans. However, their
presence in food products is an indicator of human hygiene because disease-causing bacteria pass through
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