Spectral Characterization of Fungal Metabolites in Aqueous Medium with Humus Substances

D A Khundzhua,S V Patsaeva,V I Yuzhakov,V A Terekhova

doi:10.1155/2013/538608

Abstract

The work is targeted to confirm participation of microscopic fungi in transformation of humus substances in aquatic environments. The research is focused on the spectroscopic study of the collection of fungal strains with different pigmentation of mycelium. Spectral properties of fungal metabolites were measured and compared to that of natural aquatic nonliving organic matter and commercial humus substances in aqueous solutions. The experiments revealed that the effect of microscopic fungi growing in the culture medium with added humate appeared as changes in the humic-type fluorescence: its characteristics became more similar to that of nonliving organic matter in natural waters than to original humate preparation. The experiments demonstrated degradation of coal-originated humate due to microbial activity into compounds of smaller molecular size and increased heterogeneity. We resume that transformation of humus substances by fungal cultures can be monitored and characterized using spectral measurements.

Highlights

Aqueous nonliving organic matter (NOM) and soil humus substances (HSs) are natural organic compounds representing the largest pool of carbon on the Earth [1]
Our work is aimed to con rm participation of microscopic fungi in transformation of humus substances. It is focused on uorescence spectroscopic study of the collection of microfungal strains with different pigmentation of mycelium, for which we previously revealed the dependence of growth rate on presence of humus substances in the medium [31]. e objective of the work is a detailed study of uorescence properties of fungal metabolites in the medium without and in presence of commercial HS
Our experiments revealed that the effect of fungi growing with HS in the culture medium appeared as signi cant changes in the humic-type uorescence. e value of quantum yield of humictype uorescence for HS modi ed by fungi increased and its emission maximum were essentially shi ed towards shorter wavelengths compared to that for original humate solution

Summary

Introduction

Aqueous nonliving organic matter (NOM) and soil humus substances (HSs) are natural organic compounds representing the largest pool of carbon on the Earth [1]. It was established that some fungi are capable to produce dark-brown polymers in the presence of dead plant biomass and thereby might contribute to the pool of humus or humic-like substances in salt marsh estuaries [24, 25]. A great interest in studying the processes of organic matter turnover in soil and aqueous ecosystems is focused on nonbasidiomycetous microfungi, other important groups of soil and amphibious microscopic fungi like Deuteromycetes or ascomycetes. Our work is aimed to con rm participation of microscopic fungi in transformation of humus substances It is focused on uorescence spectroscopic study of the collection of microfungal strains with different pigmentation of mycelium (from uncolored to dark colored), for which we previously revealed the dependence of growth rate on presence of humus substances in the medium [31]. It is focused on uorescence spectroscopic study of the collection of microfungal strains with different pigmentation of mycelium (from uncolored to dark colored), for which we previously revealed the dependence of growth rate on presence of humus substances in the medium [31]. e objective of the work is a detailed study of uorescence properties (change of emission maximum, uorescence quantum yield) of fungal metabolites in the medium without and in presence of commercial HS

Experimental

Results and Discussion

Conclusions