Segula Masaphy

Degradation of atrazine by the lignocellulolytic fungus Pleurotus pulmonarius during solid-state fermentation

The biotransformation of atrazine added to a mixture of cotton and wheat straw (CWS) and inoculated with the white-rot fungus, Pleurotus pulmonarius, was studied, as a proposed system for bioremediation. The concentration of methanol-extractable atrazine was reduced, due to both biological transformation and physical-chemical adsorption to the straw. Only 32% of the total radioactivity added as 14C-ring-labeled atrazine to pasteurized CWS inoculated with Pleurotus was extracted two weeks after fungal colonization, and less than 70% from non-inoculated CWS. The reduction in extractable radioactivity increased with time of incubation. No mineralization of the triazine ring was found during six weeks of incubation, but transformation to two groups of atrazine metabolites, chlorinated and dechlorinated, occurred, as a result of the activity of the fungus inoculated and natural bacterial population. Unextractable radioactivity was recovered after digesting the colonized substrate with H2SO4, indicating adsorption of the herbicide and its metabolites to the straw. The results suggest that this process can be used to detoxify atrazine by both adsorption and biodegradation.

Chemical and physical parameters in recycling organic wastes for mushroom production

Abstract Standard chemical and physical methods were defined for the analysis of substrates for mushroom production. These parameters were set according to the local conditions in Israel and they enabled the development of a quality-control system for the production of substrates for mushrooms.

Effect of medium composition on 1-octen-3-ol formation in submerged cultures of Pleurotus pulmonarius

The effect of nitrogen and fatty-acid-rich substrates on the production of 1-octen-3-ol by the edible fungus Pleurotus pulmonarius, during growth in both shaken flask and fermentor cultures, and in-vitro, in post-harvested mycelium, was studied. Addition of soybean flour and soybean oil to the growth medium enhanced 1-octen-3-ol production about sevenfold and doubled the fungal biomass, as compared to that obtained from P. pulmonarius cultured on a defined synthetic medium. A clear relationship between the production of 1-octen-3-ol and lipoxygenase activity was found during the growth of mushroom pellets. The highest in-vitro generation of 1-octen-3-ol was obtained upon addition of exogenous linoleic acid and pure O2 to pellets grown with soybean fluor and soybean oil. This generation was even higher than that of fruiting bodies exposed to the same conditions. These results suggest that lipoxygenase activity and, subsequently, 1-octen-3-ol biosynthesis in P. pulmonarius are enhanced by the presence of substrates containing fatty acids in the growth medium.

The effect of lignocellulose on lignocellulolytic activity of Pleurotus pulmonarius in submerged culture

SummaryThe possible effects of lignocellulose substrate on lignocellulolytic activity of the fungus Pleurotus pulmonarius was studied in submerged culture. This study included fungal growth rates, nitrogen and carbon consumption, and enzymatic activity rates, with and without added cotton-wheat straw (CWS) mixtures. Addition of CWS to the media caused increased consumption of glucose and NHinf4sup+by the fungal mycelium, induced carboxymethylcellulase (CMC-ase), increased poly-B decolourization, and enhanced the activity of laccase tenfold, while β-glucosidase activity was also enhanced: its first peak was higher and second peak earlier. Lignin peroxidase, however, was not detected. These results give some indication that the lignocellulolytic activity of P. pulmonarius in liquid culture is enhanced by the presence of lignocellulosic substrates such as CWS.

Role of Fungal Mycelium in the Formation of Carbonate Concretions in Growing Media—An Investigation by SEM and Synchrotron-Based X-Ray Tomographic Microscopy

Soil fungi can facilitate calcification. Mushroom Morchella sp . mycelium induced the formation of carbonate concretions on the surface of an organic-based growing media amended with sand and ground limestone. According to SEM observation and X-ray-tomographic microscopy a dense mycelial network induced calcification. The CaCO3 content of concretions (ø: 0.3–1.5 cm) was found to be at 30%. Microsparitic calcite cemented the pores between the sand grains forming a dense clogging microstructure. Besides water uptake by the mycelium, a high evaporation rate and a decrease in pCO2 contributed to the formation of the concretions. Fungal mycelium in the concretions is surrounded by voids indicating that at the surface of the mycelium, calcification is counteracted most probably by the release of organic acids.

Introduced Tuber aestivum replacing introduced Tuber melanosporum: a case study

A Tuber melanosporum plantation established in 1994/1995 on Kibbutz Bar’am (in the Upper Galilee, Israel) gradually lost its T. melanosporum mycorrhiza. In 1999, T. aestivum inoculated seedlings were inadvertently introduced into the plantation to fill the gaps between trees. A single T. melanosporum fruit body was found in 1999. Although no truffles were found after 1999 and until 2009, in that year and in 2010, truffles were collected. Morphological and molecular analyses proved these to be T. aestivum. Thus, the intentionally introduced T. melanosporum mycorrhiza was replaced by that of another introduced mycorrhizal fungus, T. aestivum. Local oak species produced higher yields compared to introduced host species known to be good T. melanosporum plant symbionts. The yield was comparable to that reported for young commercial orchards, but the fruiting season was earlier than in Europe.

Bulk treatment of substrate for the cultivation of Shiitake mushrooms (Lentinus edodes) on straw

A bulk treatment of substrate was developed for the cultivation of Shiitake mushrooms (Lentinus edodes) on a 1:1 mixture of cotton and wheat straws (CWS). The treatment is based on bulk pasteurization of CWS and the cultivation of mushrooms on 20-kg units of it. The advantages of this treatment lie in the reduction of energy and labor costs and the utilization of abundantly available wastes for mushroom cultivation.

Strain selection for cultivation of Shiitake mushrooms (Lentinus edodes) on straw

Abstract A two-stage method of strain selection was developed for optimal adaptation of the production of Shiitake mushrooms ( Lentinus edodes ) on straw substrate. The use of esterase isoenzymes, to indicate genetic variations, and mycelium growth rates, as a criterion for strain/substrate compatibility, were combined as tools for selection. The strains that were selected (four out of 22) developed fruit bodies on cotton and wheat straws mixtures (CWS), but only two of them gave yields on cotton straw (CS) alone. Biological efficiency reached 82% for CWS and 46% for CS in commercial-scale production trials.

Induction of linoleic acid-supported benzo(a)pyrene hydroxylase activity by manganese in the white rot fungus Pleurotus pulmonarius

Linoleic acid (LA)-supported benzo(a)pyrene (BAP) hydroxylation was observed in the cytosolic fraction of the white rot fungus Pleurotus pulmonarius after incubation of the mycelium with manganese (Mn+2). Linear relationships were obtained between the indelible activity and manganese concentration added to the fungal medium, and the LA and BAP concentration added to the enzymatic reaction mixture. Cytochrome P450 inhibitors nordihydroguaiarefc acid, ketoconazole, piperonyl butoxide and carbon monoxide inhibited the induced activity. The results suggest that the presence of Mn and LA in the fungal environment could enhance P450-mediated degradation of xenobiotic compound such as BAP.

Comparison of rose bengal-chloramphenicol and modified aureomycin-rose bengal-glucose-peptone agar as media for the enumeration of molds and yeasts in water by membrane filtration techniques

The present study compares the suitability of rose bengalchloramphenicol (RBCh) and modified aureomycin-rose bengal glucose-peptone agar for enumerating fungi recovered from diverse water sources using the membrane filtration method. Both mold and yeast colonies were established more rapidly, with more intensified colony colors and higher RBCh counts.