Аннотация:Humic substances (HS) are defined as the products of complex transformation of organic
residues with both biotic and abiotic factors being involved in this process. Among the biotic
factors much attention has been paid recently to xylotrophic microorganisms with particular
emphasis on white-rot fungi as they produce a wide spectrum of extracellular oxidoreductases
providing HS transformation. However, interactions of white rot fungi with HS are poorly
elucidated. In the current study uptake of HS by Basidiomycete was investigated under different
carbon source availability (nutrition media with or without glucose were used).
Experiments were performed using pure culture of Basidiomycete Trametes maxima 0275
(Wulf. Ex. Fr) Quel. and tritium labeled leonardite HS ([3H]HS). After 7 d of T. maxima
submerged cultivation [3H]HS were added into the medium to final concentration 50 mg l–1
followed by subsequent cultivation for another 24 h. Performed experiments showed that HS
were easily sorbed by fungi mycelium, and a significant portion of HS introduced could be found
in the intracellular space of fungi.
Amount of HS sorbed by fungi was estimated as 0.52±0.05 and 1.1±0.3 mg g–1 of fresh
mycelium weight for the case of nutrition medium with and without glucose respectively. It
should be noted also that along with increase of the amount of HS sorbed under carbon
deficiency conditions the value of HS penetrated cells raised as well. When glucose was added,
the value of HS penetrated the cells was accounted for 0.17±0.02 mg g–1 of fresh mycelium
weight whereas in case with absence of glucose that value increased to 0.56±0.09 mg g–1. So,
our experiments demonstrated that depending carbon source presence or absence the amount
of HS penetrated value varied from 32 to 51% of humics totally taken up by fungi. The latter was
evident for the fact that HS were seemingly to be utilized by fungi as an alternative carbon
source.