Isolation and Functional Characterization of Beneficial Bacteria Associated with Roots of Thysanolaena Maxima and Rhizospheric Soil Enzymatic Activities in Jhum Agriculture

Abstract

The activity of amylase (AMY), arylsulphatase (ASA), β-glucosidase (GSA), dehydrogenase (DHA), acid-phosphomonoestarase (PHA) and protease (PRO) enzymes were analyzed in rhizospheric soils of broom grass, Thysanolaena maxima (TM) collected from fallow phases of 5 and 20 years Jhum cycles (F5 and F20, respectively) and their corresponding bulk soils. The activities of soil enzymes from rhizospheric soil of TMF5 were significantly higher relative to that of bulk soils and the rhizospheric soils from TMF20. The counts of rhizobacteria [0.74 ± 0.056 x 107 colony forming unit (cfu) g-1 soil] and root endophytic bacteria (0.083 ± 0.004 x 104 cfu g-1 roots) of TM from F20 fallow phase were higher compared to the counts of rhizobacteria and endophytic bacteria (0.27 ± 0.029 x 107cfu g-1 soil and 0.05 ± 0.008 x 104 cfu g-1 roots, respectively) of TM from F5 fallow phase. Altogether 63 isolates associated with TM were screened for multifaceted plant growth promoting (PGP) traits viz. production of pectinase and cellulase, IAA like substances, 1-aminocyclopropane-1-carboxylate deaminase (ACCD), N2-fixation, solubilisation of inorganic phosphorus (iP) from Ca3(PO4)2, AlPO4 and FePO4 and mineralization of organic phosphorus (Na-phytate). The PGP screening results indicated that the percent incidence of rhizobacteria and root endophytic bacteria for PGP traits was higher in F5 fallow phase as compared to F20 fallow phase. These results provided clear indication that TM plants play an important role in rejuvenating the biological activities (in terms of higher activities of enzymes in rhizospheric soils and greater population of beneficial rhizobacteria and root endophytes) in frequently burnt soils under shorter Jhum cycles.