Iranian Journal of Biotechnology
Volume:9 Issue: 2, Spring 2011

Arachidonic acid is an essential fatty acid in human nutrition. In the present study, production of arachidonic acid by Mortierella alpina CBS 754.68 was evaluated in submerged fermentation. The fermentation variables were selected in accordance with the Plackett-Burman (PB) design and further optimized via response surface methodology (RSM). Five significant variables, namely glucose, yeast extract, temperature, agitation rate, and fermentation time were selected for the optimization studies. The statistical model was constructed via central composite design (CCD). Following the optimization step arachidonic acid production increased by approximately 660.5%, when compared to the screening step. The results indicate that carrying out the fermentation under the conditions of glucose at 50 g/l; yeast extract at 14 g/l; temperature of 22°C; agitation rate of 180 rpm, and fermentation time of 8 days will increase the arachidonic acid production up to 3 g/l. Results show that the optimization of culture conditions could greatly increase arachidonic acid production by Mortierella alpina CBS 754.68.

The purpose of this study was utilization of low quality date syrup as a rich and available source of nutrient in Iran for production of bacterial cellulose by Gluconacetobacter xylinus. In this study, static batch fermentation for bacterial cellulose production was studied in low quality date syrup and sucrose solution (Bx. 10%) at 28 °C using G. xylinus (PTCC, 1734). The yield of bacterial cellulose production at different fermentation times was investigated. The results showed that the maximum yield of bacterial cellulose were 4.35 and 1.69 g/100 ml for date syrup and sucrose media after 336 hours fermentation period, respectively. Fourier transform infrared spectroscopy (FT-IR) used to determine the functional groups of the samples. Comparison of FT-IR spectrum of commercial plant cellulose as a standard with the bacterial cellulose indicated appropriate coincidence which proved that the component produced by G. xylinus was cellulose. To determine the physical structure of the bacterial cellulose and standard cellulose fibers, scanning electron microscopy (SEM) was carried out in 1k magnification. The results obviously indicated more delicacy of bacterial cellulose fibers relative to that for standard cellulose. Determination of the area under x-ray diffractometry patterns demonstrated that the crystallinity amount of cellulose (83.61%) was more than that for the BC (60.73%).

L-asparaginase is an anti-neoplastic agent used in the chemotherapy of lymphoblastic leukaemia. The present work deals with production of extra-cellular L-asparaginase from marine actinomycetes, using submerged fermentation. Marine actinomycete Streptomyces associated with marine sponge Callyspongia diffusa was isolated using specific ISP medium. Sponge-associated Streptomyces was characterized by conventional methods, and identified as Streptomyces noursei MTCC 10469. Production of L-asparaginase by submerged fermentation was carried out using medium Tryptone Glucose Yeast extract (TGY) broth. The enzyme was purified to near homogeneity by ammonium sulphate precipitation, dialysis, gel filtration on Sephadex G-100 column, CM Sephadex C-50 and SDS-PAGE. The enzyme was purified at 98.23 folds, and showed a final specific activity of 78.88 IU/mg, with 2.14% yield. SDS-PAGE of the purified enzyme revealed an apparent molecular weight of 102 kDa for it. The optimum pH, temperature and incubation time of L-asparaginase was found to be 8, 50ºC and 35 min, respectively. The study suggests that marine actinomycetes, particularly Streptomyces, may be used as a potential source of L-asparaginase.

The yeast strains that are resistant to high concentration of ethanol have biotechnological benefits and are suitable models for physiology and molecular genetics research fields. A novel ethanol-tolerant mutant strain, mut1, derived from the commercial Saccharomyces cerevisiae showed higher ethanol production, and also demonstrated resistance to ethanol but not to other alcohols, such as methanol, 2-propanol, and 1-butanol. To characterize mut1, the strain’s resistance to other organic compounds and osmotic and cell wall stresses were examined. The growth of the mut1 strain in the presence of ethyl n-caproate and 3-methyl butyl acetate, which were metabolic derivatives of ethanol, was found to be less than the wild type. On the other hand, the growth of the mut1 strain in the presence of 50% (w/v) sucrose and 1M NaCl was similar to that of the wild type. The sensitivity to cell wall digestive enzyme, zymolyase, was also similar in both wild and mut1 strains. Finally, the mut1 strain showed resistance to homocysteine and serine but was sensitive to methionine. These results suggest that the ethanol resistance of the mut1 strain may be more related to the ethanol metabolic and signalling pathways rather than the enhanced stress resistances relating to the membrane or cell wall compositions.

Bovine spongiform encephalopathy (BSE) is a fatal infectious neurodegenerative disease in cattle, characterized by the accumulation of an abnormal, protease-resistant prion protein (PrPSc) in the brain. BSE is similar to scrapie in sheep and goats and Creuzfeldt-Jakob disease in humans. Susceptibility in cattle has been shown to be under the influence of two polymorphic locations, which are a 23 bp in/del polymorphism and a 12 bp indel within intron 1 of the prion protein gene (PRNP). DNA was extracted from blood samples of three Iranian cattle populations including Sistani (Bos indicus) (n=60), Golpayegani (Bos indicus) (n=62) and Iranian Holstein (Bos taurus) (n=50), In order to identify the putative polymorphisms of the PRNP gene of those breeds. Allele, genotype and haplotype frequencies of the polymorphisms were determined for the three populations. Susceptibility analysis was considered as per literature, upon which, it was suggested that the two Bos indicus native populations are more resistant to BSE than the Iranian Holstein (Bos taurus), due to higher gene frequency for insertion allele of the intron 1 of the PRNP gene polymorphism.

In order to investigate molecular diversity of mtDNA in Azery population, 133 Azery subjects were selected who were habited in different regions of Azerbaijan (Iran). From 133 subjects who are living in different parts of Azerbaijan, blood samples were taken. mtDNA of samples were studied by PCR-RFLP method. Fourteen haplogroups were found which 82% of them were European specific haplogroups, H haplogroup was the most frequent haplogroup and 79 haplotypes were specified. All specific haplogroups of Asians, Europeans and African were found in Azerian population. Iranian Azery populations in this study were a heterogenic population. Comparing the haplogroups of present study with other populations indicated a very close similarity with other Iranian populations and was different with haplogroups of Asian populations who talked Azery language; however subjects of this study were influenced by other Azery’s.

Heme oxygenase 2 (HMOX2) is a critical anti oxidative stress enzyme found in the endothelial cells and adventitial nerves. This enzyme in conjunction with other heme oxygenase 1 and 3 enzymes metabolizes heme molecules into ferrous iron, carbon monoxide (CO) and biliverdin which is further converting to bilirubin. Both biliverdin and bilirubin are potent antioxidants, reducing the chance of atherosclerosis. HMOX2 also induces endothelial relaxation by synthesizing CO. This is the first study to evaluate association of heme oxygenase 2 gene mutation in 137 patients affected with atherosclerosis and 100 normal controls with premature atheroesclerosis. Pairs of primers were designed to amplify exons 2 to 4 from HMOX2 gene. These products were analyzed by PCR-SSCP analysis and sequencing. The level of Iron and Bilirubines (Total, Direct and Indirect) were determined in both patients and control groups.). Two nucleotide substitutions were observed among 13 patients consisted of, one newly reported transversion mutation, C to A substitution in codone A70D (GCC to GAC) (Ala to Asp) and one already reported transition mutation, A to G substitution in codone K89E (AAG to GAG) (Leu to Glu). Significant associations were obtained between A437G substitution in codon K89E of hemoxygenase 2 gene (P< 0.006 and χ2 >6.82), total bilirubin (P< 0.016 and χ2 >6.01) and indirect bilirubin (P< 0.016 and χ2 >5.99) and risk of atherosclerosis but with no significant associations to the level of serum Iron P> 0.10 and direct bilirubin P> 0.24. No significant associations were observed among C381A substitution in codon A70D, P< 0.11 and χ2 >2.97, level of serums Iron P> 0.57 and bilirubins (Total P> 0.50, Direct P> 0.34 and Indirect P> 0.45) and risk of atherosclerosis. This finding presents the importance of A437G substitution in the development of atherosclerosis. Further studies are required to study the association of hemoxygenase 2 gene mutations with atherosclerosis in other populations.

In this study the ability of Acidithiobacillus ferrooxidans, with regard to the biorecovery of heavy metals in shake flask has been investigated. Adaptation experiments with the single metal ions Ni, Co, V, Mo, W and a mixture of the first four metal ions in the medium was developed through serial sub-culturing. Adaptation showed that A. ferrooxidans could tolerate up to 2.3 g/l Ni, 1.4 g/l Co, 1.4 g/l V, 0.045 g/l Mo and 0.005 g/l W, singly. In the presence of multi-metals considering a mixture of Ni-Co-V-Mo, the bacteria was able to tolerate up to 1.5 g/l Ni, 0.8 g/l Co, 0.8 g/l V and 0.05 g/l Mo in steps of 50-100 mg/l for Ni, Co and V, while for Mo and W with increments in concentration of 1-5 ppm, because of the high toxicity of these two metals to the bacteria. Adaptation of the bacterial strain was carried out in batch cultures by continually growing the bacteria in an environment containing increasing concentrations of the toxic metal such that a culture tolerant to the toxic metal proliferates. Effects of several variables such as pH, Eh, bacterial concentration in the solution as well as its resistance to heavy metals and ferrous and ferric iron concentration for the specific bacterial growth rate, were also investigated. This study showed that the various concentrations of Ni, Co and V had little effect on the oxidation of ferrous iron or the cell growth of A. ferrooxidans, whereas Mo and W ions were very inhibitory towards the Fe+2 oxidation ability of A. ferrooxidans.

Calpastatin is an endogenous inhibitor of calpain (calcium-dependent cysteine protease). Calpastatin activity is highly related to the rate of protein turnover and rate of meat tenderization. In order to characterize the structure of calpastatin in Iranian Afshari breed of sheep, intron 6 and partial exon 7 of the L domain were amplified and sequenced. A fragment of approximately 1.5 kb was identified. In this study, an Afshari calpastatin gene fragment that encoded L Domain amino acids was detected. Hence by detection of such conserved mutations, it is possible to use these polymorphisms in Marker-Assisted Selection (MAS).