Temporal variations in the abundance of heterotrophic bacteria in ground water according to land use patterns in Mysore district, India

Abstract

Temporal variations in the abundance of heterotrophic bacteria were studied from February 2005 to January 2007, in ground waters from Agricultural, Domestic and Industrial land use areas. The lowest mean abundance (AODG ml^-1) of Free Living Bacteria (2.2 × 10⁵), Particle Bound Bacteria (0.07 ×10⁵) and Total Bacteria (2.28 ×10⁵) was recorded in ground water of Agricultural area; and the highest (1.07 × 10⁶, 1.13 ×10⁵ and 1.70 ×10⁶, respectively) in that of Domestic area. In this investigation, 2.79% of the total bacteria determined by Acridine Orange staining in the ground water of Agricultural area could be grown on the artificial nutrient agar media and the comparative proportion in groundwater under the industrial area was 3.60 and 4.69% in the domestic area. Statistical analysis of the data revealed that several Physico-chemical parameters (Lab pH, air temperature, water temperature, conductivity, rainfall, BOD, CO₂, alkalinity, hardness, ca, Mg, PO₄, CL₂, NO₃, SO₄, Total Anion of Strong Acid, Total Solids, Total Dissolved Solids and Total Suspended Solids) (p < .05) were potentially responsible for some of the temporal variations in heterotrophic bacterial abundance, suggesting the influence of landusespecific environmental stressors on the biota in these ecosystems.

Key words: Temporal variation, heterotrophic bacterial abundance, colony forming units, Acridine Orange Direct Count, Direct Epifluroscence Microscopic Technique, ground water, land use patterns.