Characterization of Fungal Communities in Limed and Unlimed Lands Contaminated with Metals: Phospholipid Fatty Acid (PLFA) Analysis and Soil Respiration

Abstract

Northern Ontario (Canada) especially the Greater Sudbury region is highly known for its nickel, copper and other metal deposits. The mining, roasting and smelting of these elements have caused disastrous effects on the vegetation and overall environment. Dolomitic lime which contains calcium and magnesium carbonate was applied to soils from 1980 to 1995 at different locations across Northern Ontario. The objective of the present study is to determine fungi diversity and abundance in selected limed and unlimed areas contaminated with metals in the Region. Soil respiration, fungi cultures and Phospholipid Fatty Acid (PLFA) were analyzed. The liming did maintain an increase in soil pH from extremely acid to slightly acid, even 25 to 30 years after liming applications. A total of 52 fungi species belonging to 34 genera were identified on growth media. The majority of fungi (up to 70%) in all the sites belong to the Ascomycota phylum. Some species were specific to one or two sites, while others were present in the majority of the sites. Fungal diversity and abundance were higher in limed soils compared to unlimed samples based on SDA medium growth. The rates of soil respiration in limed sites were also higher compared to unlimed areas. Phospholipid Fatty Acid (PLFA) analysis revealed a significantly higher total microbial biomass in samples from limed areas compared to unlimed samples. Total and arbuscular mycorrhizal fungi abundance based on this analysis followed the same trend. Surprisingly, there were 7 to 10 fold more bacteria than fungi in all the sites. Moreover, there was twice more Gram (-) bacteria than Gram (+) indicating that the sites are still severely stressed. Soil pH appears to be the most important factor for microbial abundance, diversity and activities than total metal content.