Iranian Journal of Biotechnology
Volume:7 Issue: 4, Autumn 2009

In the present study، Streptomyces gulbargensis and its mutant form، S. gulbargensis mu24، immobilized on polyurethane foam were investigated for the production of L-asparaginase using groundnut cake extract as medium. The medium with an initial pH of 8. 5 was inoculated with free and immobilized cells separately and then subjected to fermentation by incubation at 40oC and shaking at 200 rev/min. In the immobilized cell system، enzyme production was enhanced by approximately 30% compared to the conventional free-cell fermentation. The immobilized cells were subjected to repeated batch fermentation processes to determine their reusability. These cells retained their ability to produce L-asparaginase over seven cycles and the activities remained between 16. 2-41. 3 IU/ml and 39-60 IU/ml for S. gulbargensis and S. gulbargensis mu24، respectively. The maximum enzyme titer was obtained during the third batch by both strains. However، the mutant strain was more potent for L-asparaginase production than the prototype. Therefore، the polyurethane foam immobilized cells of S. gulbargensis mu24 can be proposed as an effective biocatalyst، which can be repeatedly used for maximum production of L-asparaginase.

AbstractThe present investigation was aimed at studying the effect of incubation period، media، vitamins and solvents on biotransformation of albendazole by Cunninghamella blakesleeana. The transformation was evaluated and identified by high performance liquid chromatography (HPLC) and the structures of the transformed products were assigned by liquid chromatography-tandem mass spectrometry (LC/MS/MS) analysis. The fungus was found to metabolize albendazole into albendazole sulfoxide (M1)، albendazole sulfone (M2) and the N-methyl metabolite of albendazole sulfoxide (M3). Incubation period was found to influence the biotransformation significantly; 4 days was found to be optimum، but the effect was neither linear nor progressive. There was a significant effect of medium on the extent of biotransformation، with the highest substrate depletion produced by the glucose broth. The media also influenced qualitative metabolite formation. Presence of thiamine in the glucose media produced the maximum extent of transformation when compared to other vitamins studied. Dimethylformamide produced a higher extent of biotransformation. The fermentor was found to produce an increased level of biotransformation as compared to that obtained in shake flasks.

A bacterial strain (designated as Alcaligenes sp. MS-103) isolated from oil sample of the Aghajari oilfield in the south of Iran، was able to produce an effective extracellular lipopolysaccharide biosurfactant (1. 2±0. 05 g/l) on molasses as a sole carbon source. The highest surface tension reduction to level 20 mN/m was achieved by biosurfactant produced by cells grown on molasses under optimum conditions. The optimum values of carbon to nitrogen ratio (C/N)، salinity، pH and temperature for biosurfactant production were determined as 60:1، 7. 5%، 7. 0 and 50°C، respectively. Biosurfactant flooding experiments were carried out on both fractured and unfractured carbonate cores. The highest recovery of residual oil among different experiments was about 10. 7% in the unfractured cores. Oil displacement indicates that recovery of crude oil can be increased by 9. 2% from fractured core with a permeability of 12 mD. The results showed that the biosurfactant produced by Alcaligenes sp. MS-103 has the potential for industrial applications and may be used in microbial enhanced oil recovery (MEOR).

AbstractCoQ10 and lycopene are isoprenoid compounds with nutraceutical and pharmaceutical benefits. In this study، the effect of concomitant lycopene biosynthesis on CoQ10 accumulation in transformed Escherichia coli DH5α was studied. A lycopene production pathway including geranylgeranyl diphosphate synthase (crtE)، phytoene synthase (crtB)، and phytoene desaturase (crtI) from Erwinia herbicola was constructed in two CoQ10-producing E. coli strains. E. coli Ba and E. coli Br containing dds orthologs encoding for decaprenyl diphosphate synthase (Dds)، respectively from Agrobacterium tumefaciens and Rhodobacter sphaeroides were transformed by the lycopene pathway resulting in E. coli Ba-lyc and E. coli Br-lyc. The lycopene pathway in E. coli Br-lyc interestingly resulted in a significant increase in CoQ10 production from 564 ± 28 to 989 ± 22 mg /g DCW. To confirm that the improvement of CoQ10 production in E. coli Br-lyc was due to lycopene biosynthesis and not just geranylgeranyl diphosphate formation in the lycopene pathway، crtE was only introduced into E. coli Ba and E. coli Br strains. Surprisingly، crtE expression had adverse effects on CoQ10 production in both strains. The results shed light on the Dds-catalyzed reaction as a bottleneck controlled by precursors; and the efficiency of a parallel lycopene pathway to streamline the flow of metabolites.

AbstractThis study aimed at applying both growth and survival approaches to compare three native strains of lactobacilli، belonging to Lactobacillus plantarum، Lactobacillus rhamnosus and Lactobacillus acidophilus species، with two commercial probiotic strains in their tolerance to acid and bile. The association between the data obtained from the methods was studied. The results of the different methods applied in this study، did not confirm each other for all the examined strains. However، the native strain of L. plantarum and the commercial strain of L. acidophilus repeatedly demonstrated the most and least bile resistances، respectively. The former excelled in all growth approaches but showed moderate acid resistance in the survival studies. Bile stress seemed to have more detrimental effects on all examined strains. The overall results suggest that the growth-rate designed studies and survival studies evaluating transit tolerance، might bring up different results when the examined strains belong to different species of lactobacilli showing different growth and metabolic activities. The strain of L. plantarum examined here could thus be considered as a potential probiotic، regarding its overall resistance to acid and bile.

This study aimed to evaluate the genotype and gene frequencies of Leptin Gene (LEP) and its association with growth and carcass traits in three Iranian sheep breeds. The breeds included Chaal، Zandi and Zel. Genomic DNA extracted from the whole blood samples and PCR was carried out in order to amplify 260 bp fragment of the exon 2 and part of intron 2. Polymorphisms were detected using single strand conformation polymorphism (SSCP) technique. Frequencies of A and G allele were 0. 76، 0. 24، 0. 85، 0. 15 and 0. 82، 0. 18 in the Chaal، Zandi and Zel breeds، respectively. Chi-Square test confirmed Hardy-Weinberg equilibrium for the LEP loci. Average observed heterozygousity of the LEP locus was slightly low. The PCR fragments were sequenced. Comparison of the sequences of the results showed a single nucleotide polymorphisms A→G transition at the 113th bp position of intron 2 of LEP gene. In the Chaal breed، the A113G SNP is associated with increase of fat-tail and total body fat. In the Zel breed، the A113G SNP is associated with increase of fat-tail and reduction of lean meat of the carcass traits. Therefore، there is significant association between A113G SNP and carcass traits in Iranian sheep breeds.

Presence of antibiotic resistance markers has always been considered as one of the main safety concerns in transgenic plants and their derived products. Elimination of antibiotic selectable markers from transgenics faces a major hurdle for finding efficient and safe candidates. Until now، herbicide tolerance genes seem to be attractive alternatives. In this study، a variant form of 5-enoylpyruvyl shikimate-3-phosphate synthase (EPSPS) gene that harbors G96A and A183T substitutions and confers higher resistance against broad-spectrum herbicide، glyphosate، was replaced with spectinomycin resistant gene as a sole selectable marker for plastid transformation of Nicotiana tabacum. A previous study showed that، glyphosate herbicide imposes lethal effects on the structure and integrity of plastids membrane، even in low concentration. In order to overcome this problem، we used an altered procedure for selection of transplastomic cells. Long preculture incubation followed by slowly increased glyphosate concentration let sufficient expression of the transgene and tolerant calli were regenerated through direct selection of transformed plastids in the presence of the glyphosate.

Polymorphism of β-lactoglobulin (β-LG) gene in a Holstein herd was investigated by PCR-RFLP method. In the main part of the study 101 Holstein cows were screened. In this herd، the allele frequencies of β-LG A and B were 0. 53 and 0. 47، respectively and genotype frequencies for β-LG AA، AB and BB genotypes were estimated as 0. 257، 0. 544 and 0. 198، respectively. Genotypes were distributed according to the Hardy-Weinberg equilibrium. Results indicated that β-LG genotypes affected significantly milk yield (genotype AA > genotype BB) (P < 0. 01). Furthermore، polymorphism of the gene was investigated in a superior cow، producing more than 150 Kg per day، (and 4 of her offspring)، belonging to another herd in the same region. Genotype of the cow and her offspring were determined by the same method and all were heterozygote (AB).

A pair of degenerate primers, GMPF1 and GMPR1, was designed on the basis of alignment of previously reported Grapevine fanleaf virus (GFLV) movement protein (MP) nucleotide sequences from Iran and other parts of the world. cDNA was synthesized by the use of Oligo d(T)18 from total RNA extraction from each diseased grapevine leaf sample and subjected to polymerase chain reaction (PCR) with the degenerate primers under a range of annealing temperatures from 48 to 62°C. It was revealed that 55°C gave the best result in terms of producing exactly the expected fragment (1044 bp) from as many samples as possible although accompanied by few fade non specific fragments. However, by application of “hot-start” PCR and annealing at 60°C the specific fragment was amplified from 41 out of 86 samples. This was the first amplification of the precise MP cDNA from GFLVs in Iran which is very important as to preparation of recombinant anti-GFLV MP antibody to use in studying the GFLV- grapevine interaction, and also for generating pathogen-derived resistant vines.