Isolation and Screening of Cellulose Degrading Microorganisms from Forest Floor Litters of Jhum Fallows

Abstract

Fallow period of a Jhum cycle is the recuperation phase of Jhumming practice, where most of the processes like regeneration of secondary forest, equilibration of biomass (forest litter fall) decomposition and nutrient cycling processes take place. Biomass decomposition is considered to be the key process that supports all other biogeochemical processes. In the present study, litter falls from 4 different Jhum cycles viz. 2, 5, 10 and 20 years were collected from Jhum fields of Mizoram. Since cellulose is the most important component of plant biomass and a source of carbon, the cellulose degrading microorganisms (CDMs) were isolated from these litter falls and screened for their ability to degrade carboxy-methyl-cellulose (CMC) in agar plates as substrate. Based on halo formation in CMC plates, the colony forming unit (cfu) counts of CMC decomposers were recorded in the order of 20 ≥ 10 > 2 > 5 years fallow period. The cfu counts in cellulose agar media ranged from 5.2 × 106 to 9.9 × 107 cfu g−1 litter fall, showing the lowest in 5 years fallow and the highest in 2 years fallow. The cellulase activity ranged from 3.06 to 227.8 µg mL−1 h−1. In conclusion, Jhum fields seem to harbour substantial population of CDMs during fallow period with an indication of higher population in 2 years, which subsides in 5 years and upsurges again at 10–20 years. The activity of decomposer community found more prominent in the longer fallow period.