Thirty-one bacterial isolates out of 133 isolates, were obtained from rhizosphere of Egyptian clover plants, and had variant capability for starch degradation on starch agar medium. The isolate E109 was the most potent being 72.5 U ml À1 and 2.5 for amylase activity and starch hydrolysis ratio (SHR), respectively, at 50°C. The potent isolate E109 was identified based on phenotypic characteristics, phylogenetic positions based on 16S rRNA gene analysis and base sequences (submitted to NCBI Gen Bank). 16S rRNA gene analysis confirmed that this isolate belonged to the genus Bacillus and it was most closely related to B. amyloliquefaciens (95% similarity). For the production of amylases, nine agro-industrial residues were added as carbon sources to the basal medium. The medium supplemented with potato starchy waste as the sole carbon source enhanced the enzyme activity more than soluble starch as control for a, b and c amylases activity, as it increased by B. amyloliquefaciens about 1.26 & 4 and 8-fold, respectively after 48 h at 50°C using rotary shaker at 150 rpm. B. amyloliquefaciens gave the maximum values of a, b and c amylases activity on medium supplemented with 2% potato starchy waste after 30, 30 & 36 h of fermentation periods at 50°C using shake flasks technique as a batch culture. These values were 155.2 U ml À1 (R 2 = 0.93), 1.0 U ml À1 (R 2 = 0.94) and 2.4 U ml À1 (R 2 = 0.95), respectively. It could be stated that productive medium supplemented with 2% potato starchy waste as a low price substrate could be more favorable than basal medium containing 1% starch for amylases production in submerged fermentation, as it increased a, b and c amylase activity by 1.98, 7.69 and 12-fold than that produced in basal medium (control), respectively. ª 2015 Production and hosting by Elsevier B.V. on behalf of Faculty of Agriculture, Ain Shams University.

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The present study aimed at developing a strategy to improve the volumetric production of PHAs by Pseudomonas fluorescens S48 using waste frying oil (WFO) as the sole carbon source. For this purpose, several cultivations were set up to steadily improve nutrients supply to attain high cell density and high biopolymer productivity. The production of PHAs was examined in a 14 L bioreactor as one-stage batch, two-stage batch, and high-cell-density fed-batch cultures. The highest value of polymer content in one-stage bioreactor was obtained after 60 h (33.7%). Whereas, the two-stage batch culture increased the polymer content to 50.1% after 54 h. High-cell-density (0.64 g/L) at continuous feeding rate 0.55 mL/l/h of WFO recorded the highest polymer content after 54 h (55.34%). Semi-scale application (10 L working volume) increased the polymer content in one-stage batch, two-stage batch and high cell density fed-batch cultures by about 12.3%, 5.8% and 11.3%, respectively, as compared with that obtained in 2 L fermentation culture. Six different methods for biopolymer extraction were done to investigate their efficiency for optimum polymer recovery. The maximum efficiency of solvent recovery of PHA was attained by chloroform–hypochlorite dispersion extraction. Gas chromatography (GC) analysis of biopolymer produced by Pseudomonas fluorescens S48 indicated that it solely composed of 3-hydrobutyric acid (98.7%). A bioplastic film was prepared from the obtained PHB. The isolate studied shares the same identical sequence, which is nearly the complete 16S rRNA gene. The identity of this sequence to the closest pseudomonads strains is about 98–99%. It was probably closely related to support another meaningful parsiomony analysis and construction of a phylogenetic tree. The isolate is so close to Egyptian strain named EG 639838.

T HE CURRENT research deals with optimization of the factors affecting lipase production under submerged culture system. The most efficient isolate R1 was identified depending on cultural and morphological characteristics together with 18S rRNA sequence as Rhizopus oryzae. Using one variable at a time, the maximum lipase activity (171.8 U/mL) was recorded in the presence of 1% fish-frying oil, mixture of peptone and yeast extract at pH 5 with 8% v/v of fungal inoculum after 4 days at 30°C. The screening of the most significant factors using Plackett-Burman design revealed that among ten variables, four, i.e. incubation temperature, inoculum size, incubation period and agitation speed, affected significantly (p-values ranged from 0.003 to 0.049) on the lipase activity. Optimization by using response surface methodology (RSM) through central composite design (CCD) resulted in the highest predicted lipase activity (216.2 U/mL) in which fermentation medium was inoculated with 8% inoculum size and incubated at 28°C under agitation speed of 150 rpm for 4 days.

Background Rhizopus species is among the most well-known lipase producers, and its enzyme is suitable for use in many industrial applications. Our research focuses on the production of lipase utilizing waste besides evaluating its applications. Results An extracellular lipase was partially purified from the culture broth of Rhizopus oryzae R1 isolate to apparent homogeneity using ammonium sulfate precipitation followed by desalting via dialysis. The partially purified enzyme was non-specific lipase and the utmost activity was recorded at pH 6, 40 °C with high stability for 30 min. The constants Km and Vmax, calculated from the Lineweaver-Burk plot, are 0.3 mg/mL and 208.3 U/mL, respectively. Monovalent metal ions such as Na+ (1 and 5 mM) and K+ (5 mM) were promoters of the lipase to enhance its activity with 110, 105.5, and 106.5%, respectively. Chitosan was used as a perfect support for immobilization via both adsorption and cross-linking in which the latter method attained immobilization efficiency of 99.1% and reusability of 12 cycles. The partially purified enzyme proved its ability in forming methyl oleate (biodiesel) through the esterification of oleic acid and transesterification of olive oil. Conclusion The partially purified and immobilized lipase from Rhizopus oryzae R1 approved excellent efficiency, reusability, and a remarkable role in detergents and biodiesel production.

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