Synthesis of some new thiazole derivatives. antifungal activity and ultrastructure changes of some mycotoxin producing fungi.

Several new thiazoles 2-7,10-12; 2,3-diphenyl-5-(2-thienyl)imidazo[2,1-b]thiazole 8, 3,5-di-(2-thienyl)imidazo[2,1-b]thiazole 9 and 4-amino-2-imino-6-(2-thienyl)thiazolo[3,2-a] pyrimidine 13 and 6-(2-thienyl)-3H-thiazolo[3,2-a]pyrimidin-2,4-diones 14 have been synthesized. The prepared compounds were evaluated for their in-vitro antifungal activity, compared with Tioconazol fungicide. The strong antifungal activity is elicited by compounds 5 and 8. The most active compound 5 was found to induce changes in the ultrastructure of mycotoxin producing fungi (Aspergillus flavus and Aspergillus ochraceus), this was observed by both scanning and transmission electron microscopy.

Optimization of process parameters for the continuous ethanol production by Kluyveromyces lactis immobilized cells in hydrogel copolymer carrier.

In the present study the optimized parameters for highest ethanol productivity by Kluyveromyces lactis immobilized cells bioreactor were obtained using the method of Lagrange multipliers. Immobilized growing yeast cells in PVA: HEMA (7%: 10%, w/w) hydrogel copolymer carrier produced by radiation polymerization were used in a packed-bed column reactor for the continuous production of ethanol from lactose at different levels of concentrations (50, 100 and 150) gL(-1). The results indicate that volumetric ethanol productivity is influenced by substrate concentration and dilution rate. The highest value 7.17 gL(-1) h(-1) is obtained at higher lactose concentration (150 gL(-1)) in feed medium and 0.3 h(-1) dilution rate. The same results have been obtained through the application of "LINGO" software for mathematical optimization.

Ethanol production by Kluyveromyces lactis immobilized cells in copolymer carriers produced by radiation polymerization.

The conditions for batch and continuous production of ethanol, using immobilized growing yeast cells of Kluyveromyces lactis, have been optimized. Yeast cells have been immobilized in hydrogel copolymer carriers composed of polyvinyl alcohol (PVA) with various hydrophilic monomers, using radiation copolymerization technique. Yeast cells were immobilized through adhesion and multiplication of yeast cells themselves. The ethanol production of immobilized growing yeast cells with these hydrogel carriers was related to the monomer composition of the copolymers and the optimum monomer composition was hydroxyethyl methacrylate (HEMA). In this case by using batch fermentation, the superior ethanol production was 32.9 g L(-1) which was about 4 times higher than that of cells in free system. The relation between the activity of immobilized yeast cells and the water content of the copolymer carriers was also discussed. Immobilized growing yeast cells in PVA: HEMA (7%: 10%, w/w) hydrogel copolymer carrier, were used in a packed-bed column reactor for the continuous production of ethanol from lactose at different levels of concentrations (50, 100 and 150) g L(-1). For all lactose feed concentrations, an increase in dilution rates from 0.1 h(-1) to 0.3 h(-1) lowered ethanol concentration in fermented broth, but the volumetric ethanol productivity and volumetric lactose uptake rate were improved. The fermentation efficiency was lowered with the increase in dilution rate and also at higher lactose concentration in feed medium and a maximum of 70.2% was obtained at the lowest lactose concentration 50 g L(-1).

Phenylalanine ammonia lyase production by gamma irradiated and analog-resistant mutants of Rhodotorula glutinis.

Mutants resistant to phenylalanine analogs (L-tyrosine, p-fluoro-D, L-phenylalanine (PFP) and trans-cinnamic acid) were isolated from a wild type strain of Rhodotorula glutinis A-97 by mutagenic treatment with gamma radiation and screened for phenylalanine ammonia lyase (PAL) production. One such mutant, gammaT11 (resistant to L-tyrosine), exhibited four times the PAL activity of the parent wild strain A-97. Mutant isolate gammaTFP5.6 which was selected as L-tyrosine and PFP resistant isolate, produced inducible PAL activity at levels 5.94-fold higher than the wild-type A-97 and 2.66-fold higher than its parent mutant isolate gammaT5 which was resistant to L-tyrosine. The mutant isolate gammaTC5d which was resistant to L-tyrosine and trans-cinnamic acid, exhibited 3.48 and 1.56-fold increase in PAL activity compared to the parent wild strain A-97 and its parent mutant isolate gammaT5, respectively. Different media have been examined for the induction of PAL.