Growth Stimulatory Effects of Enterobacter and Serratia Isolated from Biofilms on Plant Growth and Soil Aggregation

Twelve bacterial strains of family Enterobacteriaceae were isolated from different biofilms. Total nine biofilms were collected from polluted as well as from non-polluted environments. Isolates were purified and characterized both morphologically and biochemically. Total eleven strains were affiliated with Enterobacter while only one showed affinities with Serratia. Isolated strains of Enterobacter and Serratia were used to inoculate the seedlings of Zea mays in mono and mixed culturing. The growth parameters of Zea mays seedling and soil aggregation were recorded. Monoculture inoculations caused an increase in all length parameters i.e., shoot length, root length, seedling length of Zea mays seedlings. Number of roots decreased and number of leaves remained constant. When all these strains were used as mixed culture, a decrease in all length parameters i.e., shoot length, root length, seedling length was observed while number of roots increased and number of leaves decreased. Monoculture inoculation resulted in increase in weight of aggregates on roots and causing decrease in weight of aggregates in soil. In mixed culture inoculation, weight of aggregates on roots as well as in soil was decreased over control.