Recovering Greater Fungal Diversity from Pristine and Diesel Fuel Contaminated Sub-Antarctic Soil Through Cultivation Using Both a High and a Low Nutrient Media Approach

Belinda C Ferrari,Josie Van Dorst,Chengdong Zhang

doi:10.3389/fmicb.2011.00217

Abstract

Novel cultivation strategies for bacteria are widespread and well described for recovering greater diversity from the “hitherto” unculturable majority. While similar approaches have not yet been demonstrated for fungi it has been suggested that of the 1.5 million estimated species less than 5% have been recovered into pure culture. Fungi are known to be involved in many degradative processes, including the breakdown of petroleum hydrocarbons, and it has been speculated that in Polar Regions they contribute significantly to bioremediation of contaminated soils. Given the biotechnological potential of fungi there is a need to increase efforts for greater species recovery, particularly from extreme environments such as sub-Antarctic Macquarie Island. In this study, like the yet-to-be cultured bacteria, high concentrations of nutrients selected for predominantly different fungal species to that recovered using a low nutrient media. By combining both media approaches to the cultivation of fungi from contaminated and non-contaminated soils, 91 fungal species were recovered, including 63 unidentified species. A preliminary biodegradation activity assay on a selection of isolates found that a high proportion of novel and described fungal species from a range of soil samples were capable of hydrocarbon degradation and should be characterized further.

Highlights

The isolation of fungi into pure culture has been severely limited
Limitations in cultivation methods are thought to be attributed to fast-growing fungal species outcompeting slower growing species, many fungi are not adapted to growth in high nutrient media, and a proportion of fungi will not sporulate in artificial culture media (Taylor et al, 2000; O’Brien et al, 2005)
Global R values that result from these analyses provides an absolute measure of how separated the groups are, on a scale of 0 for groups that are indistinguishable, to a value of 1, where all similarities within groups is less than any similarity between groups

Summary

Introduction

The isolation of fungi into pure culture has been severely limited. Of the estimated 1.5 million species that are thought to exist less than 5% have been successfully recovered into pure culture (Hawksworth, 2001; O’Brien et al, 2005). Limitations in cultivation methods are thought to be attributed to fast-growing fungal species outcompeting slower growing species, many fungi are not adapted to growth in high nutrient media, and a proportion of fungi will not sporulate in artificial culture media (Taylor et al, 2000; O’Brien et al, 2005). Novel cultivation methods for the recovery of yet-to-be cultured species have been well described for bacteria and include the application of simulated natural environments, extended incubation times, and/or the use of limited nutrients (Janssen et al, 2002; Kaeberlein et al, 2002; Rappe et al, 2002; Ferrari et al, 2005). Novel approaches to culturing fungi that utilize low levels of nutrients or simulated natural environments have not yet been adopted

Methods

Results

Conclusion