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Lipases (triacyl glycerol acyl hydrolase) catalyze hydrolysis and syntheses of ester formed from glycerol and long-chain fatty acids. They have many industrial applications, especially in food and detergent industries. Out of 33 bacterial isolates, a group of 20 bacterial isolates produced lipase enzyme on tributyrin agar and Tween 80 agar media. In liquid medium, the lipase activity was ranged from 1.5 to 6.9 IU/ml. Among the evaluated bacteria, the isolate LP10 that was isolated from soil collected from fuel station. It was the most active isolate in lipase production (6.9 IU/ml). Using morphological, physiological and biochemical studies, it was identified as an isolate belonging to the genus Streptomycesand identified as Streptomyces exfoliates LP10. Identification was confirmed using 16S rDNA analysis. Growth of the selected bacterium in medium containing tributyrin and Tween 60 at initial pH 6 in addition to incubation at 37°C for three days yielded the maximum lipase production. The molecular weight of the purified enzyme was 60 kDa, determined using gel electrophoresis. Improvement of lipase production was carried out between Streptomyces exfoliates LP10 and Streptomyces niveus using protoplast fusion. Five fusants were obtained. Fusant LP3 was the best lipase producer (3 times higher) compared to its parents. Key words: Lipase, Streptomyces exfoliates, tributyrin, protoplast fusion, 16S rDNA.

Acinetobacter baumannii, Corynebacterium sp., Cytophaga columnaris, Escherichia coli,Pseudomonas fluorescence and Pseudomonas luteola were locally isolated bacteria from sewage Disposal Lake at Jeddah, Saudi Arabia and they can decolorize methylene blue.E. coli was the most potent MB decolorizing and to a lesser extend P. luteola. Five different media were tested to elucidate medium formulation in favor of MB decolorization by E. coli and P. luteola. Ingredients of the basal medium favored the complete decolorization of 50 µ QUOTE QUOTE g MB/ml after 84 h of fermentation. Time course decolorization of MB by E. coli indicated that 75 h of fermentation was satisfactory to decolorize 50 µ QUOTE QUOTE g MB/ml. It was also able to decolorize different levels of MB up to 150 µ QUOTE QUOTE g MB/ml after 95 h of fermentation. Bacterial consortium of E. coli and P. luteola was highly efficient to decolorize MB than monoculture, where the decolorization period reduced by more than 37% and increased decolorization rate (µgMB/h) up to 58%. Statistical designs of two phase multifactorial optimization (Plackett-Burman and Box-Behnken) were carried out to optimize cultural conditions to increase the efficiency of mixed culture to decolorize 150 µg MB/ml. Under the optimized conditions the decolorization period was reduced by about 31.7% and with increased decolorization rate by 46.4%. Methylene blue can be efficiently decolorized by facultative aerobic bacteria (E. coli and P. luteola). The decolorization process was markedly influenced by the composition of the fermentation medium and concentration of MB. Mixed culture of E. coli and P. luteola was highly efficient to decolorize MB than monoculture technique. The cultural conditions were considerably optimized using statistical experimental designs of Plackett-Burman and Box-Behnken. Key words: Methylene blue, Escherichia coli, Pseudomonas luteola, mixed culture, statistical optimization.

This study focus on the production of antibacterial compound from Trichoderma spp. Screening of antibacterial activities in some Trichoderma spp. was investigated using CYS80 medium. Trichoderma reesei and Trichoderma viride were highly effective toward human-pathogenic bacteria tested. T. viride and T. reesei were separately applied on Sephacryl S–200 column. Column fractions No. 56 to 64 for T. viride and fractions No. 57 to 66 for T. reesei had inhibitory effect against the most pathogenic bacteria examined. T. reesei and T. viride Sephacryl S-200 fractions with antibacterial activity were analyzed byGas chromatography–mass spectrometry (GC- MS). The product with highest peak (95%), using different libraries, was kojic acid. The yield of kojic acid crystals from T. reesei and T. viride Sephacryl S-200 fractions were 3 and 5 g/L, respectively. Physical analysis of kojic acid with respect to UV, IR, 1HNMR analysis and melting point was examined. The minimum inhibitory concentration (MIC) of kojic acid and augmentin, as control, against human-pathogenic bacteria were evaluated. Kojic acid and augmentin showed a similar time-killing kinetics with human-pathogenic bacteria. The level of kojic acid increased with decreased level of reducing sugar during the growth of T. reesei and T. viride suggesting that the enzyme system for the synthesis of kojic acid found in the cell of these fungi. Key words: Trichoderma spp., human-pathogenic bacteria, kojic acid, minimum inhibitory concentration.