Effect of long-term industrial pollution on soil microorganisms in deciduous forests situated along a pollution gradient next to a fertilizer factory 1. Abundance of bacteria, actinomycetes and fungi

摘要

Soil fungi, bacteria and actinomycetes were studied in seven unequally polluted forest plotssituated at different distances from a fertilizer factory in Lithuania. Average numbers ofcolony forming units in 1 g of dry weight soil (CFU g~(-1)) were determined by plate count onappropriate media: fungi on malt extract agar (MEA), bacteria on nutrient agar (NA), andactinomycetes on starch-casein agar (SCA). During the investigation period (2001-2002),the concentration of viable fungi varied from 23.3 to 387.9 thousand, bacteria - from 380.2thousand to 9.02 million, and actinomycetes - from 0.11 to 7.58 thousand CFU g~(-1) of soil.Negative correlation between the fungal and actinomycetal concentrations and the dis-tance from the pollution source (r = -0.56 and r = -0.05, respectively) was determined.Content of some heavy metals (Cu, Cr, Cd, Ni and Zn) in soil positively correlated withthe humus content, but did not correlate with the distance from the pollution source. Thehighest concentration of heavy metals was determined in the soil of the plot situated at adistance of 5 km from the pollution source. Significant and high positive correlation be-tween the fungal concentration and nitrogen (r = 0.77), phosphorus (r = 0.88) and humus(r = 0.74) content in soil was determined. The lowest number of fungal genera was deter-mined in the forest plots where contents of the heavy metals (especially Pb, Cr, Zn and As),nutrients (nitrogen, phosphorus), and humus in soil were the highest. The results showedthat abundance of bacterial and fungal populations increased within factory-induced soilpollution, but the diversity of species was decreased.