Temporal Changes in Soil Microbial Diversity of Tropical and Sub-Tropical Forests of Mizoram, Northeast India

摘要

Microbes are ubiquitous in the soil and abundantly available even in a small amount of soil and are represented by group of bacteria, fungi and actinomycetes. Studies are more abundant on bacterial and fungal population while actinomycetes are less studied. We studied seasonal changes in all three groups of soil microbes in tropical (approx 100 m altitude) and subtropical (approx 1350 m altitude) forest settings. Soil samples were collected from two forests during June 2015 to May 2016 every three months interval based changes in temperature and precipitation. Using serial dilution Method, different agar media was prepared separately for assessing bacteria, fungi and actinomycetes, for example, nutrient agar with nystatin and actidione for bacteria(using dilution 10~(-5) to 10~(-7)), potato dextrose agar (PTA) with rose bengal, antibiotic (i.e.penicillin and chloramphenicol) for fungi (10~(-3) to 10~(-5)) and starch case in agar (SCA) mixed with nystatin were used for isolation of actinomycetes (10~(-4) to 10~(-5)). For each group of microbes, 1 ml diluted liquid was added into petri-plates containing solid media (triplicates) and incubated in BOD at different temperature. Soil microbial population in the present study varied significantly with respect to changes in abiotic variables. Significantly higher microbial populations were recorded during rainy season compared to other seasons. The soil microbial diversity in the present study changes as function of rainfall and its associated variables. For instance, in sub-tropical forest, rainfall accounted for 97% variability in fungal population and 94% in the actinomycetes population. However, in tropical forest, rainfall and soil moisture together accounted for 99% variability in the populationof actinomycetes. We suggest more frequent recording of microbial population and abiotic variables for studying the impact of climate variables on soil microbial diversity in these forests.