Aspergillus niger Environmental Isolates and Their Specific Diversity Through Metabolite Profiling

Abstract

We present a biological profile of 16 Aspergillus niger environmental isolates from different types of soils and solid substrates across a pH range, from an ultra-acidic (<3.5) to a very strongly alkaline (>9.0) environment. The soils and solid substrates also differ in varying degrees of anthropic pollution, which in most cases is caused by several centuries of mining activity at old mining sites, sludge beds, ore deposits, stream sediments, and coal dust. The values of toxic elements (As, Sb, Zn, Cu, Pb) very often exceed the limit values. The isolates possess different macro- and micromorphological features. All the identifications of Aspergillus niger isolates were confirmed by molecular PCR analysis and their similarity was expressed by RAMP analysis. The biochemical profile of isolates based on FF-MicroPlate tests from the Biolog system showed identical biochemical reactions in 50 tests, while in 46 tests the utilisation reactions differed. The highest similarity of strains isolated from substrates with the same pH, as well as the most suitable biochemical tests for analysis of the phenotypic similarity of isolated strains, were confirmed when evaluating the biochemical profile using multicriterial analysis in the Canoco program. The isolates were screened for mycotoxin production by thin-layer chromatography (TLC), as well. Two of them were able to synthesise ochratoxin A, while none produced fumonisins under experimental conditions. Presence of toxic compounds in contaminated sites may affect environmental microscopic fungi and cause the genome alteration, which may result in changes of their physiology, including the production of different (secondary) metabolites, such as mycotoxins.

Polyphasic Characterization of Four Aspergillus Species as Potential Biocontrol Agents for White Mold Disease of Bean

“…The diversity of Aspergillus species is correlated with their ability to utilize a wide variety of organic substrates and adapt well to a broad range of environmental conditions [ 38 ]. A. niger , for example, is a common soil fungus that can live in different types of soils across a pH range from a highly acidic to a strongly alkaline environment [ 39 ]. Similarly, A. japonicus is found in soil and has also been known to adapt to agricultural environments and farmed animals [ 40 ].…”

Experimental Treatment of Hazardous Ash Waste by Microbial Consortium Aspergillus niger and Chlorella sp.: Decrease of the Ni Content and Identification of Adsorption Sites by Fourier-Transform Infrared Spectroscopy

“…In the exteriors, experiments were conducted under static conditions, and in this case, too, we recorded lower values of Ni content reduction in the aqueous medium (samples 9 and 10) compared with the anhydrous environment (samples 11 and 12). The species A. niger is a known producer of many organic acids and secondary metabolites ( Šimonovičová et al, 2020 , 2021 ) which are used in bioleaching processes. It can be assumed that in the case of adding distilled water, the organic acids produced were diluted, which caused a slowing down/reduction of the bioleaching process from the solid substrate.…”

“…A cosmopolitan strain of A. niger ( Figure 2A ) was isolated from Dystric Cambisol (contaminated and eroded) without vegetation. The chemical characteristics of the substrate showed an ultra-acidic soil reaction (pH 3.12), a very low amount of organic matter (%C ox 0.49) and exceeded the value of aluminum (Al 727 mg kg –1 ) ( Šimonovičová et al, 2021 ).…”

Using Fungi and Bacteria as Biological Control Agents of Fungal Plant Diseases an article

“…The ability of Aspergillus species to exploit a wide range of organic substrates and successfully adapt to a wide range of environmental conditions is connected with their diversity [27]. A. niger considered the common soil fungus and can survive in a variety of soil types with pH values ranging from extremely acidic to extremely alkaline [28].…”