The cultures of filamentous fungi in aquatic medium release fluorescent metabolites (FM) with emission spectra that closely match the typical fluorescence bands found for soil extracts and aquatic fluorescent dissolved organic matter (FDOM). FM released from some fungal cultures show as well comparable values of fluorescent quantum yield, the blue shift of emission spectra excited in the UV, and a very close match of ultraviolet–visible absorbance spectral curves related to soil and aquatic FDOM, further strengthening the similarity of fluorophores in those aquatic material. Given the importance of microscopic filamentous fungi in the global carbon cycle, our results indicate that filamentous fungi are likely to be important sources of aquatic and soil FDOM of microbial origin.
Soil fungi are actively involved in the processes of humic substances synthesis, transformation and mineralization due to production of extracellular nonspecific oxidative enzymes. The work was aimed to evaluate using spectral methods transformation dynamics for the humic product (HP) from lignosulfonate (HPligno) by filamentous soil fungal cultures Alternaria alternata and Trichoderma harzianum. Experiments showed that direct spectroscopic study of HPligno introduced into the nutrient medium and its transformation during fungal growth is challenging due to strong absorption of light by nutrient medium, development of absorbing fungal metabolites, partial utilization and destruction of HP by fungi and therefore due to the need to register tiny changes in overlapping bands. To accomplish that task we proposed a novel algorithm for processing the absorption spectra, which has not previously been used to study fungal cultures. We calculated the second-order derivative in respect to wavelength for absorption spectra measured during fungal growth and found characteristic "patterns" for introduced HP: a maximum at 270-285 and a minimum within 290-300 nm. The spectral index determined from amplitudes in the second-order derivative spectrum reflects the relative content of HP in the nutrient medium in presence of other absorbing components. We resume that two fungal strains utilized HPligno in the 0,02 and 0,1% concentrations better at 30 g/L sucrose than at 3 g/L in the medium. Thus the second-order differentiated absorption spectra helped to quantify degradation of the HPligno during fungal growth.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.