Genetic variability and vegetative compatibility in Aspergillus niger isolated from various food substances in Benin City Nigeria

L Eboigbe,M.O Omoregbe

doi:10.4314/jasem.v24i12.23

Abstract

In this investigation, Aspergillus niger isolated from eight food substances, have been classified based on the absence of heterokaryon formation. The size of their sporangia were differentiated, the wild and mutant strains were subjected to vegetative compatibility tests in order to group them into different vegetative compatibility groups (VCGs) which include VCG-1, VCG-2, VCG-3 and VCG-4. The strains were further tested for the possible formation of a stable heterokaryon using nit mutants generated on potato dextrose agar (PDA) containing 2.5% chlorate (KClO3), represented as PDC. Based on the vegetative compatibility groups, nit mutants were paired on a minimal medium (MM) for complementation test. Interestingly, there was compatibility with mycelia showing anastomoses but without the formation of heterokaryon. The vegetative compatibility groups suggested four genotypes and polymorphism in the het loci. A population study for detailed genotyping is suggested in order to unravel the genetic recombination in A. niger.

Highlights

Aspergillus niger (Tiegh) is a common saprophyte that is found in the soil, feed products and stored food (Diener 1960)
This filamentous fungus has a wide array of oxidative and hydrolytic enzymes involved in the breakdown of plant lignocellulose (Gautam et al, 2011) and it is known to be responsible for the spoilage of food substances
Attempt to unravel the genetic basis of recombination in A. niger has met with obstacle due to lack of heterokaryon formation

Summary

Introduction

Aspergillus niger (Tiegh) is a common saprophyte that is found in the soil, feed products and stored food (Diener 1960). The genetic basis of recombination is well established in some sexual filamentous fungi but is unknown in the (presumably) asexual A. niger (Frisvad et al, 2014). This currently hinders the involvement of A. niger in genetic analysis. The high degree of incompatibility raise the question of how is recombination possible between different isolates when both the sexual and parasexual cycles are missing or blocked (Pal, 2007) It was on this basis, we decided to check the variability in isolates from the various food substance and their vegetative compatibility levels, perhaps, and this might reveal some cryptic sexual or parasexual cycle. This was use in this research to demonstrate the extent of genetic diversity among

Methods

Results

Conclusion