Evaluation of lipid-producing yeast for biodiesel production

FUNGAL xylanase and lignin peroxidase enzymes were used as pretreatment for biobleaching of bagasse biopulping treated with mixed culture of Ophiostoma piliferum and Ceriporiopsis subvermispora SS- 33 at 27°C for one week in MV medium as static culture before the pulping with propylene glycol [PG]. Some agricultural wastes such as corn cobs, wheat bran and bagasse powder were used as a sole carbon source for xylanase production. The maximum production of fungal xylanase was attained after 7 days- fermentation period on corn cobs medium at 30°C on rotary shake flasks at 150 rpm. The enzyme production by Trichoderma reesie NRRL 6156 increased 1.17 fold as compared with that obtained by Trichoderma viride NRRL 13034.Using 10.30 IU xylanase/g bagasse biopulp, produced by Trtchoderma reesie NRRL 6156, for 4 h at 50°C was the best xylanase pretreatment which reduced klason lignin% and increased the brightness % of bagasse biopulp. The solid-state HC-LN medium supplemented with tween 60 and veratryl alcohol in addition to 10 grams of bagasse pulp was the best one for lignin peroxidase production by Phanerochaete chrvsosporium NRRL 6361, the enzyme activity of this treatment [77.75 IU/L] was higher than that obtained using semi-solid [47.75 IU/L] and liquid [36.50 IU/L] state, after 6 days incubation period. The optimum lignin peroxidase dose, for the best biobleaching of unbleached bagasse biopulp at 37°C for 8 h was 1.54 lU/g. Using these enzyme pretreatments led to increase the brightness %, breaking length and tear factor 6.7, 18.89 and 12.7 % by xylanase bleached bagasse [XBB] and 8.94 %, 34.92 and 30.82 %, by lignin peroxidase bleached bagasse [LBB], respectively. The enzyme treatment of LBB and XBB led to decrease of chlorine consumption 40% and 26.67 % as compared to control. Scanning electron microscope [SEM] of bleached bagasse pulp clearly showed fiber that exposed to enzymes treatment had a more open surface and it becomes more accessible to subsequent bleaching agents. The biologicaly pretreatment of bagasse pulp with xylanase orlignin peroxidase enzymes led to increase in the crystallinty by 11.29 and 8.3 %, respectively

Ecological studies on soil indigenous rhizobia in Egypt 3-Intrinsic antibiotic Resistance [TAR] for differentiation of rhizobia

antibiotic marking is generally used in following up the persistence of induced rhizobial strains to soils. As well known maximizing symbiotic N[2] fixation requires a great understanding of the ecology of rhizobia. One of the major limitations in study of this symbiosis is the difficulty in recognizing strains of rhizobia in their natural habitats. Intrinsic antibiotic resistance [IAR] of 131 Rhizobium isolates 381 belonging to clover, 21 to chickpea and 29 to pea towards low, moderate and high concentrations of 13 antibiotics was investigated. All isolates possessed IAR character but the number of antibiotics resisted varied and the resistance ability of most isolates decreased with the increase of antibiotic concentration in the culture medium [YMA]. Use of low or moderate concentrations gave more reliable information about the IAR character. Gentamycin and Kanamycin have the most suppressive effect on the three species of tested rhizobia, R. leguminosarum bv. trifolii, R. spp. and R. leguminosarum bv. viceae. Chickpea Rhizobium was also affected by streptomycin at the three levels of concentration, while pea isolates severely affected also by polymyvin especially at moderate and high levels of antibiotic since none isolates could grew on the medium Spectinomycin was of moderate effect on growing of pta Rhizobium

Antimicrobial activity of some Egyptian medicinal and aromatic plant waste extracts

A comparative study on the antimicrobial activity of some medicinal and aromatic plant wastes was done on a number of bacterial and fungal strains adopting the discdiffusion assay. Thirty extracts from Allium sativum L., Cympopogon sp., Nigella satival l., Ocimum basilicum L. and Thymus basilium were evaluated. Thymus basilium possessed the highest antimicrobial effect followed by Nigella sativa L., with respective average inhibition zone diameters of 4.7 and 3.8 mm. Fungal candidates were inhibited by plant extracts to higher extents as compared to bacterial strains, [inhibition zones measured were 5.9 mm for the former and 3 mm for the latter]. No remarkable variations were observed among the two methods used for extraction. The photochemical screening of plant waste extracts indicated the presence of carbohydrates, tannins, alkaloids, flavonoids, sterols, saponins and coumarins