Additives in Powder Based formulation for Enhanced Shelf Life of Pseudomonas fluorescens and Bacillus sp.

Studies were carried out to evaluate the effect of adding nutrient additives to talc based formulations on the shelf life of bacteria stored under room temperature. Two organisms namely, Pseudomonas fluorescens (PDBCAB2) and Bacillus sp. (MTCC6534 - chickpea endophyte), a spore forming bacterium, were tested. A gradual increase in P. fluorescens population up to 90 days was observed in almost all the treatments that were amended with nutrients. At 90 days highest population of log 10.38 cfu g⁻¹ was noticed in talc amended with 2 per cent tryptone and glycerol. Decline in the population was observed from 90 days onwards and was rapid from 150 days onwards. At 240 days highest count of log 1 x 10^4.2 cfu g⁻¹ was obtained with formulations amended with 2% tryptone and 2% glycerol and the results indicated that 2% peptone or 2% tryptone supplemented with 2% glycerol helped P. fluorescens in its better survival. The spore forming Bacillus sp. survived well throughout the study period. At 240 days all talc formulations amended with nutrient sources showed a population of log 9.0 cfu g⁻¹ or above and the population declined to below log 7.0 cfu g⁻¹ only in non amended treatments. Slow decline started from 240 days but high cfu of log 9.30 to 9.38 g⁻¹ were noticed in yeast extract or tryptone treated treatments. Hence talc formulations that had yeast extract or tryptone supplemented with glycerol enhanced shelf life of Bacillus spp.