Endoglucanase Activity of Compost-Dwelling Fungus Paecilomyces inflatus is Stimulated by Humic Acids and Other Low Molecular Mass Aromatics

Pathogenicity and enzyme screening of some selected non-dermatophytic moulds

Ten non-dermatophytic moulds isolated from both symptomatic and asymptomatic cattle skin, including Penicillum citrinum, Aspergillus welwitschiae, Aspergillus aculeatus, Curvularia kusanol, Cladosporium teniussmum, Pestalotiopsis microspora, Fusarium oxysporum, Fusarium linchenicola, Absidia sp. and Aspergillus fumigatus, were subjected to a pathogenicity test using albino mice. These isolates were also screened for five enzymes using a standard plate method. Results from pathogenicity tests showed that Absidia sp., Cladosporium tenuissimum and Aspergillus welwitschiae were able to elicit discoloration, lesion production and alopecia on the albino mice skin, respectively, providing evidence of clinical symptoms associated with cutaneous mycoses. The enzyme screening results revealed the highest zone of activity for keratinase (65 mm), amylase (86 mm), protease (60 mm), lipase (60 mm) and cellulase (86 mm) which were observed on Pestalotiopsis microspora, Aspergillus welwitschiae, Cladosporium tenuissimum, Aspergillus welwitschiae and Aspergillus welwitschiae respectively. Pathogenicity tests showed that some of these moulds may be virulent and this can be attributed to their possession of some virulence factors, including secretion of hydrolytic enzymes.

Composting of food waste subjected to hydrothermal pretreatment and inoculated with Paecilomyces sp. FA13

Food waste collected from restaurants, convenience stores, and food-processing factories was mixed with sawdust and subjected to hydrothermal pretreatment at 180°C for 30min to prepare compost raw material. Furan compounds such as 5-HMF (5-hydroxymethyl furfural) and furfural were produced at concentration levels of approximately 8 and 0.5mg/g-ds, respectively, through hydrothermal pretreatment. The furan compounds inhibited the activity of composting microorganisms, thus delaying the start of organic matter degradation during composting. A newly identified fungus, Paecilomyces sp. FA13, which possesses the ability to degrade furan compounds, was isolated and used as an inoculum for the composting of the raw material prepared by hydrothermal pretreatment. By inoculating the FA13 into the compost raw material at 10(5)CFU/g-ds, the degradation of furan compounds was accelerated. As a result, bacterial activity, which contributed to composting, was enhanced, significantly promoting the start of vigorous degradation of organic materials.

Humic substances enhance growth and respiration in the basidiomycetes Trametes maxima under carbon limited conditions

Humic substances (HS) represent the major reservoir of carbon (C) in ecosystems, and their turnover is crucial for understanding the global C cycle. Although basidiomycetes clearly have a role in HS degradation, much less is known about the effect of HS on fungal traits. We studied the alteration of physiological, biochemical, and morphological characteristics of Trametes maxima in the presence of HS. Both complete medium and minimal (C-limited) medium mimicking natural environmental conditions were used. Adding HS led to increased biomass yield, but under C-limited conditions the effect was more apparent. This result indicated that HS were used as an additional substrate and agreed with data showing a greater penetration of tritium-labeled HS into the cell interior under C-limited conditions. Humic substances induced ultra-structural changes in fungal cells, especially under C limitation, including reducing the thicknesses of the hyphal sheath and cell wall. In the minimal medium, cellular respiration increased nearly three-fold under HS application, while the corresponding effect in complete medium was lower. In addition, in the presence of inhibitors, HS stimulated either the cytochrome or the alternative pathway of respiration, depending on presence or absence of glucose in the medium. Our results suggest that, under conditions mimicking the natural environment, HS may play three major roles: as a surplus substrate for fungal growth, as a factor positively affecting cell morphology, and as an activator of physiological respiration.

Effects of potential environmental interferents on kinesin-powered molecular shuttles

Biomolecular motor-powered active transport represents an alternate means for analyte processing in nanoscale biosensors and bioanalytical devices. For example, a prototype "smart dust" biosensor has recently been reported in which the motor protein kinesin processes antibody-functionalized microtubules (MTs) to capture and separate optically tagged protein analytes. A potential limitation of this technology, however, involves the inhibition of transport function by interfering compounds that may be present in raw samples. Here we characterized the response of kinesin-MT transport to a range of potential interferents including solvents, acids, oxidizers, and environmental contaminants. The results of kinesin motility assays suggest that, among the tested interferents, only acetic acid and sodium hypochlorite adversely affected MT transport, primarily due to depolymerization of MT filaments. While negative effects were not observed for the remaining compounds tested, enhancement in motility was observed in the presence of acetone, antifreeze, and organic matter. Overall, the data suggest that kinesin-MT transport is resilient against a variety of common interferents, but primarily susceptible to failure due to significant changes in pH or the presence of an oxidizer.