NEW MICROBIAL BIOPREPARATION FOR AGRICULTURE CONSISTING OF CONSORTIUM OF BIOSURFACTANT PRODUCERS

Abstract

The present work is an attempt to create a biosurfactant producing consortia on the bases of initial rhizospheric community of lettuce plant (Lactuca sativa). To obtain consortia, 47 strains from the rhizosphere were isolated and checked upon their ability to produce biosurfactants. The ability of the isolates to produce biosurfactants was analyzed on the basis of their ability to emulsify crude oil (E24 index). The isolates with the highest E24 were Bacillus. oryzaecorticis (80%), B. simplex (65%), Paenibacillus xylanilyticus (60%), and P. illinoisensis (73%). These isolates (numbered further as 1, 2, 3 and 4, respectively) were further cultivated together in consortia of two, three or four members. The cultivation was conducted of LB and BH medium during 72 h, after that the abundance of the consortium members as well as the ability of the consortium to utilize different carbon substrates (Biolog EcoPlate� system) were assessed. It was found out, that isolate 1 was not able to grow in consortia. Other isolates were able to grow in combinations with each other, at least in one of the media. Isolate 4 survived in all the combinations investigated. Among consortia investigated, the two-members consortium 3-4 was able to survive in both media. The AWCD index reflects the average ability of the microbes to utilize 31 different carbon substrates. For individual isolates 1, 2, 3 and 4, AWCD was estimated to be 0.07, 0.04, 0.19 and 0.25, respectively. It exceeded the initial levels of AWCD demonstrated by the individual isolates only in 3 cases: 1-3-4 (0.26), 1-2-3-4 (0.32), 2-4 (0.59). It can be concluded that consortia are able to survive in larger spectrum of environmental niches as compared with individual isolates, however, competition between the consortium members limits their active growth.