Modares Journal of Biotechnology

Abstract  As a starch hydrolyzing enzyme, α-amylase is important in the food industry and ethanol and biofuel production. This research aims to investigate the production of α-amylase enzyme in microorganisms from different regions of Iran and microbial collection centers of Iran. The results showed that 183 out of 331 isolates screened had α-amylase activity. Of these, two strains isolated from agricultural soil, named AGR228 and AGR91, had the maximum halo-to-colony ratio. In addition, all the strains belonging to the microbial collection centers showed amylase activity, of which PTCC-1732 and PTCC-1156 showed the highest activity. The amount of amylase produced in PTCC-1732 and AGR228 was estimated to be 20.5 and 11.18 units/ml, respectively. The maximum activity of the amylase enzyme from PTCC-1732 is at 80°C, and  pH 10. In the case of AGR228, the maximum activity was measured at 60°C, and  pH 8.
 

Abstract Non-biodegradable metals exhibit toxicity to living organisms at high concentrations. They enter aquatic systems through various pathways, including industrial activities, often in an uncontrolled manner. Given the role of bacteria as effective biosorbents, they can be employed for the removal of heavy metals from industrial wastewater. The aim of this study was to investigate the biosorption of lead and tellurite by Shinella zoogloeoides-DSM287 and assess its potential for nanoparticle biosynthesis.
In this study, the biosorption of lead and tellurite was evaluated under various conditions, including different pH levels, temperatures, initial metal concentrations, and incubation times. Subsequently, the potential formation of nanoparticles during the biosorption process was investigated, and the presence of nanoparticles was confirmed using various analytical techniques. According to the results, Shinella zoogloeoides-DSM287 exhibited resistance to lead and tellurite, with MICs of 2400 µg/mL and 100 µg/mL, respectively. Furthermore, the bacterium acted as an efficient biosorbent for lead and tellurite ions under alkaline conditions, at temperatures between 28–32 °C, and across different incubation periods. Additionally, the bacterium was able to convert tellurite ions into tellurium nanoparticles during the biosorption process. DLS and zeta potential analyses revealed that the biosynthesized nanoparticles had an average size of approximately 150 nm and a surface charge of −34 mV. Transmission Electron Microscopy (TEM) showed the nanoparticles to be irregularly spherical in shape. In summary, the studied bacterium demonstrated a potential for the biosorption of lead and tellurite and could be considered a promising candidate for the removal of these contaminants from aquatic environments.
 

Abstract The process of soil and concrete cementation through microbial induction depends on the efficiency of the enzymes in producing bacteria. The isolation of microorganisms with high urease activity may lead to the isolation of strains that are better at cementing in compression to the current strains. This research deals with the isolation of isolates with high urease ability. Isolate 233 out of 283 isolates was associated with the best urease activity, and its urease activity was the release of 5.04 micromoles of ammonium per millilitre per minute. This isolate using sequencing of a fragment of 16SrRNA and characterization of biochemical properties was identified as Lysinibacillus sp. strain 233 was deposited in NCBI under accession number OQ379213. The semi-quantitative XRD analysis of the bacterium's calcite crystals in the precipitation medium revealed that 87.1% were calcite while only 12.9% were vaterite. FESEM electron microscope images revealed cubic calcite crystals and EDX analysis confirmed the presence of its constituent elements, i.e., carbon, oxygen, and calcium.

Abstract The aim of present research is development of a simple green approach to produce Ag/AgCl nanocomposites using bacterial strains Bacillus haynesii and Bacillus halotorans, nominated at PN14F and B3, respectively, via an extracellular process. The bacterial strains PN14F and B3 were isolated from the soil and wastewater samples, using dilution and direct cultivation method. The Ag/AgCl nanocomposites were synthesized from the reaction of silver(I) nitrate solution and supernatant under completely sterile conditions in the presence of light. Moreover, a series of controlled experiments were provided to optimize some reaction conditions such as substrate concentration, PH, substrate volume, bacterial volume, the presence of glucose as an electron donor and silver(I) nitrate as inducer. The products were characterized using various techniques such as UV-Vis, XRD, FT-IR, FE-SEM and EDX. The resulting bionanocomposites (Ag1 and Ag2), with an average particle size of 30 and 22.3 nm, were efficient heterogeneous catalysts for reducing para-nitrophenol to para-aminophenl. Further, it was demonstrated their activity as the antibacterial properties against gram positive and negative bacteria. The results showed that the Ag2 sample with reducing time of 15 min is a more efficient catalyst than the Ag1 nanocomposite, which can be attributed to the smaller size of the Ag2 nanoparticles.

Abstract Pseudomonas aeruginosa is one of the most important causes of infection in medicine, which in recent years is known as an antibiotic resistant bacterium. One of the antibiotic resistance strategies of this bacterium is algD and PpyR genes expression for biofilm formation.


In recent years, it has been shown that using microorganisms, such as probiotics, is a method of pathogen bacterium harnessing, hence, in this study, for preventing biofilm formation of P. aeruginosa, E.coli Nissle 1917(EcN) probiotic bacterium is used, as a new treatment choice.


Due to direct relationship between antibiotic resistance and biofilm formation, strains with the


highest antibiotic resistance was chosen by antibiogram test. Then, in order to determine the inhibition rate of EcN bacterium in the formation of biofilm caused by P. aeruginosa bacterium, a biofilm formation test was performed.


At the end, to evaluate algD and PpyR genes expression, which were key parts of biofilm formation, in the presence of probiotic EcN bacterium, Real- time PCR method was used.


Based on the results of the biofilm formation test, EcN bacterium showed a high inhibitory effect on the formation of biofilm caused by P. aeruginosa bacterium.


.Also, in assessment of algD and PpyR genes expression in presence of EcN probiotic, a significant reduction in PpyR gene expression has been seen, in comparison with control group. The results of this study showed that EcN probiotic can act as a suitable new treatment option, to reduce P. aeruginosa biofilm formation.

Abstract The use of productive microorganisms in the production of primary and secondary metabolites is part of the knowledge of microbial biotechnology, which is carried out with the aim of using huge cellular factories and considering their inherent and latent ability to produce products. Investigating and optimizing the factors affecting the synthesis of metabolites will increase the growth of the strain and the yield of the product. In this regard, in this research, by using the response surface method (RSM) and Box-Behnken design, the fermentation production of cephalosporin C by Acromonium chrysogenum PTCC 5271, and the effect of three factors on the fermentation process, including pH of Fermentation culture media, rice bran and magnetite iron oxide nanoparticles have been measured at three levels. The obtained results showed that changes in the concentration of magnetite iron oxide nanoparticles and rice bran in the fermentation media significantly affect the amount of antibiotics produced. The highest amount of Cephalosporin C produced (224 mg/l) was obtained in the culture containing 0.04 mg/l magnetite iron oxide nanoparticles, 2.5 g/l rice bran and pH of 6.5. The optimized values ​​for the factors were calculated as 0.0325 mg/l, 2.6162 g/l, and 6.4545 respectively by the Mini Tab program, and finally the mathematical model for the response variable was obtained. Based on the results of this research, magnetite iron oxide nanoparticles and rice bran are suitable substrates in fermentation culture media and biological processes.

Abstract Phenols are organic and highly toxic compounds commonly found in the effluents of various industries due to their wide range of applications. The inhibitory effect of phenol at high concentrations, as well as the high salinity of industrial effluents, poses a serious challenge for treatment by microorganisms. One of the most common approaches to overcome this problem is the immobilization of phenol-degrading microorganisms. The aim of this study was to study the immobilization effect on the phenol removal efficiency of native Janibacter halotolerant bacterium. For this purpose, mica was used as a carrier for bacterial immobilization and the protein concentration assay was applied to determine the immobilization efficiency. The phenol removal by free and immobilized cells was studied as well as the effect of different parameters on phenol removal efficiency. The immobilization efficacy on mica was %68.75, based on protein concentration measurements. The removal time of 100 mg/L phenol by suspended cells was 88 h, while the immobilized cells degraded it in 40 h. Immobilized cells, unlike free cells, were able to remove phenol at lowered temperatures up to 16℃ , salt concentrations greater than 7/5%, and pH levels below 7/5 and above 8/5. Similar results regarding the superior performance of immobilized cells have been obtained in other studies. As a result, the immobilization process considerably improves the efficiency of phenol removal and makes the cells resistant to harsh environmental conditions by protecting the cells from the toxic effects of phenol.

Abstract Poly-γ-glutamic acid (γ-PGA) is a beneficial, biocompatible, and biodegradable biopolymer. These properties have been led to the development of the use of this compound in various industries such as bio-medicine, biopharmaceutical, biotechnology, and tissue engineering. The limitation of the industrial development of γ-PGA is the high cost of its production. To reduce γ-PGA production costs, various strategies are used, such as culture medium optimization using inexpensive compounds, the development of efficient cultivation processes of batch and fed-batch. In this research, first, an efficient batch culture medium was developed to produce γ-PGA of Bacillus licheniformis ATCC 9945^a. Then, the γ-PGA production increased by the pulsed feeding method and its optimization. By optimal culture medium development, the production of this product in batch culture was increased from 11 g/L to 47 g/L. Then, using the optimized pulsed feeding strategy of citrate (γ-PGA precursor), γ-PGA production was increased to 59.5 g/L, which is one of the highest production values reported with this strain. To optimize two-pulse feeding, the effect of feeding times, stock citrate solution concentration, and time of calcium and manganese solutions addition on γ-PGA production were investigated and optimized. Finally, FTIR confirmed the chemical structure of poly gamma glutamic acid, and the study of γ-PGA morphological properties with SEM showed a nanostructure ideal for biological applications.

Abstract Wound healing and skin remodeling occur directly after skin damage, so the use of platelet rich growth factors (PRGF) and probiotics is important to accelerate this process because of their positive effects on wound healing and antibacterial activities. Combination of above biomaterials with tissue engineering techniques led to the production of a new wound dressing. Therefore, in this study, PRGF was obtained from platelet-rich plasma and a multi-layered scaffold was fabricated by electerospining method using polyurethane (PU) fibers, PRGF and gelatin fibers. Scanning electron microscopy (SEM), tensile and water contact angle tests were performed to assess the characteristics of the scaffolds. The human Adipose Mesenchymal Stem Cells (hAMSCs) were extracted and cultured with the fibroblast cells (HU-02) as co-culture cells and Lactobacillus plantarum was cultured on scaffolds with or without PRGF to evaluate cell viability, toxicity and proliferation, then antibacterial activities of L.plantarum were examined. The result of MTT assay after 14 days indicated that PRFG and L.plantarum had significant positive effect on viability and proliferation of co-culture cells. SEM photograph illustrated adhesion and proliferation of cells and bacteria on scaffolds up to 21 days. The Agar-well diffusion test confirmed the antibacterial effect of L.plantarum on Pseudomonas aeruginosa, Salmonella typhimurium, Staphylococcus aureus, and Escherichia coli with strong inhibition zone. The current multi-layered scaffold provides the appropriate wound dressing for cell adhesion, proliferation and prevents wound infection.

Abstract Background and Aim: Toxins produced by Clostridium botulinum are among the deadliest compounds known that cause botulism. Currently, the detection of BoNTs in food using bioassays on laboratory mice is a very sensitive method with a detection range of 7 to 20 pg.mL^-1. However, bioassay for mice is time consuming. This method is fast, highly specific, and sensitive to experiments on mice. The aim of this study was to use the modified Sandwich ELISA method to detect BoNT/B toxin.

Materials and Methods: Recombinant 370 amino acid protein was expressed from the carboxyl terminus of the binding moiety of BoNT / B toxin with a molecular weight of 45 kDa as antigen and purified by Ni-NTA affinity chromatography. IgG antibodies were isolated from mouse and rabbit sera byG protein affinity chromatography. The sensitivity and specificity of the method designed to detect recombinant BoNT/B-HcC antigen and botulinum toxin type B were evaluated.

Results: Purified rat and rabbit antibody concentrations were 3 and 4.5 mg / ml serum, respectively. The minimum concentrations of detectable protein were determined by indirect ELISA with purified mouse and rabbit antibodies at 475 and 118 pg. By optimizing the sandwich ELISA method, at least 30 ng of recombinant BoNT/B-HcC antigen and146 pg of highly specific BoNT/B were detected.

Conclusion: sandwich ELISA method can be used for accurate and sensitive identification of Clostridium botulinum toxin type B. It is necessary to evaluate the effectiveness of this method in the future to detect botulinum toxin in environmental and food samples.

Abstract

Background: Shigella and Enterohemorrhagic Escherichia coli are among the most common causes of bacterial diarrhea, and no effective vaccine candidate for these bacteria have approved yet. Due to the role of IpaD protein and Shigella enterotoxin B subunit (StxB) in Shigella and E. coli O157: H7 pathogenicity, STX1B-IpaD chimeric protein can be used as a suitable molecule to produce a recombinant vaccine candidate. This study aimed to clone, express, and purify STX1B-IpaD chimeric protein to develop an effective vaccine candidate against Shigella and E. coli O157: H7 species. Materials and Methods: IpaD gene with NdeI and BamHI restriction enzyme sites was isolated from a recombinant vector and subcloned into the pET28a -STX1B expression vector. Vector was transferred to E.coli strain Rosetta (DE3) and confirmed by PCR and restriction enzyme digestion. SDS-PAGE and western blotting were used to confirm the recombinant protein. The recombinant STX1B-IpaD protein was purified by affinity chromatography, and its concentration was measured by the Bradford method. Results: The PCR and restriction enzyme digestion showed the accuracy of the gene cloning. The protein electrophoresis showed the proper expression and correct molecular weight (27 kDa) of STX1B-IpaD. The western blot analysis confirmed the recombinant protein. The recombinant protein concentration was estimated at more than 0.3 gr/L. Conclusion: An effective method for the production of recombinant proteins is codon optimization and effective expression in heterologous hosts. After the immunogenicity in the animal model, this recombinant protein can be used as a chimeric vaccine candidate against EHEC and Shigella bacteria.

Abstract In a marine environment, the biofilm formed on the submerged surfaces leads to fouling of larger organisms. This leads to many environmental and economic problems for the marine industries. Due to the harmful effects of chemical antifouling, the development of environmentally friendly anti-biofilm strategies can be an important step to control fouling.
Therefore, the present study was performed with the aim of isolation of biofilm-forming bacteria from Persian Gulf waters and investigating the antimicrobial effect of thymol against selected bacteria.82 bacterial were isolated and their ability to form biofilm was measured. Among these, 5 isolates were selected and identified using 16S rRNA sequences. The results showed that the 5 selected isolates belonged to the Proteobacteria (genus Vibrio, Kangiella and Psudoaltromonas). In the study of the antibacterial effect of thymol, K. spongicola (PH1) showed the highest sensitivity in disk diffusion method (with a growth inhibition zone diameter of 18 ± 0.57 mm). The minimum inhibitory concentration and minimum bactericidal concentration (at 31.5 and 62.5 μg /ml, respectively) were obtained against the same bacterium. The inhibitory thymol on biofilm formation and performed biofilm by Psudoaltromonas sp. (PH18) showed that thymol at concentrations sub-MIC is able to inhibit biofilm formation. The effect of thymol on the performed biofilm at concentrations higher than MIC is noticeable. Based on the results, due to the anti-biofilm activity of thymol against marine bacteria, its use as a natural compound in antifouling coatings can be suggested.

Abstract Mutation in microbial strains to increase coenzyme Q₁₀ production is one of the successful strategies for strain development. Therefore, in this study, the production of coenzyme Q₁₀ by Gluconobacter oxydans H621 was investigated through chemical mutation with nitrosoguanidine using the response surface methodology. Nitrosoguanidine was used to induce mutations at different concentrations (2.79 - 4.21 mg/mL) and treatment times (11.89 – 33.12 minutes), which was designed by a central composite design. The detection of mutant strains was investigated through their ability to grow in medium containing 160 μg/mL of menadione. The mutant strains were then examined for coenzyme Q₁₀ and dry cell weight production. The results showed that no mutant strains were obtained at a concentration of 4 mg/ml and above. The highest number of mutant colonies was obtained at a concentration of 2.79 mg/mL of nitrosoguanidine and treatment time of 22.5 minutes. It was also found that the concentration of nitrosoguanidine was effective on mutagenesis but the treatment time had a little effect. The mutant strain that was able to produce the highest amount of coenzyme Q₁₀ produced 5.2 mg/L, which was twice as much as the parent strain. According to the results of this study, it is concluded that by inducing mutation using nitrosoguanidine, mutant strains can be generated in Gluconobacter oxydans H621 that are able to produce more coenzyme Q₁₀ than the parent strain.

Abstract Background: Carotenoids are biological antioxidants and play important roles in protecting the body from diseases and aging. Canthaxanthin is one of the most widely used carotenoids in the industry and medicine. This study aimed to investigate the biological properties of canthaxanthin pigment as well as its production optimization in a low-cost medium using a radioresistant microbial strain named Dietzia maris.
Materials and methods: Bacterial carotenoids were extracted and its antibacterial, anti-tumor, and cytotoxicity properties were investigated. Then, the effect of Krebs intermediates and pH on the production of pigment and microbial biomass in the whey medium was investigated using the response surface methodology.
Results: Maximum pigment production was found to be 92/54 mg/l in whey culture medium at pH 8 and in the presence of 12.5 mM of each of citrate, glutamate, malate, and succinate by the response surface method. The pigment did not show any cytotoxic effect on Hela, HFB, and MCF-7 cell lines. Besides, the pigment did not have any antibacterial properties.
Conclusion: Radioresistant microbial strains are better candidates for microbial pigment production due to their stability and high antioxidant activity. In this study, a whey culture medium was used to reduce the production cost of canthaxanthin. The addition of Krebs intermediaries in the fermentation medium increased the pigment production by Dietzia maris significantly.

Abstract Enzymes play an essential role in catalyzing the reactions for multiple industrial applications. One of these critical industries with a worldwide application is paper and pulp, which is cost-effective in increasing attention. Xylanases are potential enzymes that proved their abilities in a broad range of applications, specifically in the paper and pulp industry as a biobleaching agent and dye removal biocatalyst. In these decades, the production of novel enzymes from natural sources is conceivable, especially with applying the culture-independent method of metagenome. This practical approach provides the opportunity to identify the novel enzymes from uncultivable microbial diversities. Concerning the importance of the thermostable enzymes for industrial applications and their better action in harsh conditions, this study aimed to identify novel thermostable xylanase from metagenomic data of sheep rumen by applying the in-silico screening. The thermostable xylanase was extracted from the ruminal DNA and after cloning and expression named PersiXyn5. The enzymeschr('39') kinetic parameters, including Km, Vmax, and its specific activity, were examined. The enzyme was optimally active at 80 and pH 8 and could retain 58% of its maximum activity after 2h of incubation at 90 . The thermostable, alkali PersiXyn5 was an efficient enzyme in the paper industry and poultry feed and fuel applications.

Abstract Activin A, a member of the transforming growth factor-β (TGF-β) superfamily, plays a central role in numerous physiological processes such as cell differentiation, tissue repair, angiogenesis, differentiation of stem cells, cell adhesion and apoptosis. Because of its various clinical usages, recombinant production of it is beneficial. Since E. coli is one of the most popular hosts for recombinant protein production, in this study, cytoplasmic expression in this strain was used to produce high levels of Activin A. So, the cDNA of the Activin A mature region was amplified and then cloned in pET28a(+) vector. The resulting vector was transformed to BL21(DE3), BL21(DE3)plysS, and BL21(DE3)Rosetta-gami strains. After induction the promoter by using IPTG, Activin A production was confirmed by SDS-PAGE and Western blotting assays. The results showed that the expression of Activin A in the cytoplasm of all three strains was an efficient approach to obtain high levels of recombinant protein, but BL21(DE3) strain produced more protein. At the next step in order to achieve soluble form of Activin A, co-expression of cytoplasmic chaperones TF, GroEL/ES, and DnaK with pET28a (+) vector was used. The SDS-PAGE and Western blotting results showed that co-expression of Activin A with cytoplasmic plasmid pGro7 containing GroEL and GroES chaperones, in BL21(DE3) strain is an efficient approach for producing of soluble Activin A.

Abstract Klebsiella pneumoniae is a gram-negative bacillus of the Enterobacteriaceae family. Despite being part of the natural human microflora, this is an opportunistic pathogen and a major cause of nosocomial infections. The increased emergence of multidrug resistance in Klebsiella pneumoniae has limited the treatment options for this bacterium. Carbon nanotubes (CNT), by improving the stability and solubulity of drugs, could increase the effectiveness of drugs for treatment. The aim of this study is to investigate the antibacterial effect of nanofluid containing functionalized multi-walled carbon nanotubes (f-CNT-NF) on Klebsiella pneumoniae isolated from clinical specimens. For the strain confirmation, biochemical ,API20E kit, and additional differential tests were performed, and antibiotic susceptibility test was performed by the disk diffusion method. The studied strain showed a resistance to all antibiotics such as cefepime.The minimum inhibitory concentration (MIC) was determined using the antibiotic micro dilution method. The MIC was determined in five effect modes including antibiotic (Ab), nanofluid containing functionalized multi-walled carbon nanotubes (f-CNT-NF) , nanofluid containing multi-walled carbon nanotubes (CNT-NF) ,Ab in combination with f-CNT-NF and Ab with CNT-NF. Nevertheless the individual effects of 10 µg mL^-1 cefepime or 80 µg of nanofluid with f-CNT-NF did not inhibit the growth of the bacteria, but the co-administration of 10 µg mL^-1 cefepime with 80 µg of the f-CNT-NF could inhibit the bacteria`s growth. It was concluded that f-CNT-NF could be more effective in drug delivery at lower concentrations than the free state, which could be used as a tool for optimal drug delivery.

Abstract The aim of this study was to isolate and identify a-amylase-producing bacteria present in mangrove ecosystems on Qeshm Island, Hormozgan, Iran. Samples of mangrove leaves and roots were screened for a-amylase activity using Lugol’s solution. Crude extracts were prepared of positive samples, and their a-amylase activity was determined by the Bernfeld method. The two strains with the highest activity were identified by molecular analysis of their 16S rRNA genes. a-Amylase production and activity were optimized by varying temperature and pH. 46 bacterial strains were isolated from mangrove tree leaf and root samples. Of these, 28 strains were capable of producing a-amylase. 16S rRNA gene sequence analysis of two strains with the highest enzyme production identified them as Bacillus sp. strain HR10 and Bacillus sp. strain HR11. The optimum temperature for enzyme production was 35 and 30 °C for strains HR10 and HR11, respectively, and the optimum pH was pH 8 for both strains. The highest enzyme activity was observed at 70 °C and 60 °C for the HR10 and HR11 strains, respectively, and the optimum pH was pH 8 for both strains. In conclusion, we have shown that bacteria isolated from mangrove leaf and root samples are potential source of a-amylases, tolerating a wide range of temperature and pH. Such a-amylases may be of interest for use in environmentally friendly industries.

Abstract Summery
Lentinula edodes(Shitake) is one of the most popular species of edible/medicinal fungus due to its high content of protein, polysaccharide and unique aroma, which is ranked second in the world in terms of cultivation and consumption. Today, its effective compounds are used as adjunctive therapy along with chemical treatments. In this study, the culture medium, acidity and optimum growth temperature of Lentinula edodes (TMU340) mycelium were determined. Mycelium, fruiting body and whole fungi were lyophilized and the wet to dry weight ratio was obtained; Lentinan was extracted using hot water at 60°C, degassing by Sevage method and precipitation with pure ethanol at 4°C and purified by Ion exchange chromatography. Lentinan concentration was obtained by phenol-sulfuric acid test. Results, Optimum conditions including PDA and PDB media, 25°C and pH, 5.5 were determined. The wet to dry weight ratio was 10 to 1 in all samples. Lentinan concentrations after extraction and purification were 0.243, 0.103 and 0.148 mg/ml, respectively. As a result, this fungus can be useful in the production of a variety of metabolites and natural compounds without side effects such as Lentinan polysaccharide as a factor in boosting the immune system.

Abstract Nowadays, aromatic componds are widely used in food, pharmaceutical, cosmetic and chemical industries. Due to the growing tendency of consumers to use natural products, biotransformation by microorganisms is an interesting method for the production of aromatic compounds. Gamma-decalactone is a cyclic aroma with a peach-like flavor. The non-conventional yeast Yarrowia lipolytica can bioconversion the inexpensive castor oil substrate into the valuable gamma-decalactone. The process begins with the hydrolysis of castor oil by the lipase to ricinoleic acid, then continues by shortening the chain by beta-oxidation, and finally ends by lactonization. In this study, gamma-decalactone production was optimized via Response surface methodology (RSM) by a mutant strain of this yeast with the ability to produce high amounts of lipase. For this purpose, castor oil, yeast extract, peptone and pH were studied as factors at five levels. Based on statistical analysis of the relationships between the experimental variables, a mathematical model was obtained for the governing relationships between the experimental variables. Based on the results, the best values were obtained for castor oil 35 ml/l, yeast extract 6 g/l, peptone 8.5 g/l and pH 4. To validate the mathematical model, the proposed values were tested and 126 mg/L of gamma-decalactone was produced by the yeast strain, which shows a 46% increase compared to non-optimal conditions. The results of this study can be used to make cost-effective production of gamma-decalactone from castor oil by microbial biotransformation process.

Abstract Nerve growth factor (NGF) is a neurotrophic factor that is functional in survival, maintenance and differentiation of peripheral and central nervous system cells. This protein has three subunits that its beta subunit has main activity. According to scientific studies, it can be used as a therapeutic agent in treatment of many diseases such as peripheral neuropathy associated with diabetes, Alzheimer's disease, Parkinson's disease, skin disease and so on. Prokaryotic expression of recombinant NGF should be done in the periplasmic space because of its oxidative envoronment. It is worth noting that co-expression of cytoplasmic molecular chaperones can facilitate the secretion of the recombinant proteins to the periplasmic space and also enhance the protein solubility.
In this study, the effect of cytoplasmic chaperones of GroEL / GroES, DnaK / DnaJ, GrpE, Trigger Factor (TF) on the periplasmic production of recombinant NGF protein was studied. For this purpose, β-NGF subunit was expressed in pET39b(+) expression vector simultaneously with chaperone plasmids pG-Tf2, pTf16, pGro7, pKJE7 and pG-KJE8 in E. coli DE3 strain.
The results showed that in the presence of TF chaperone (pTf16 plasmid), the total protein and periplasmic production increased. Also, the DnaK/DnaJ and GroEL/GroES chaperones (pG-KJE8 plasmid) have also increased the production to some extent.; while the expression of GroEL/ GroES (pGro7) or DnaK / DnaJ (pKJE7) had no effect on protein expression. Also treatment of PC12 cell line with recombinant β-NGF showed differentiation to nerve cells which indicates that the produced protein is fully functional.

Abstract Hyaluronic acid (HA) is a natural and linear polymer that finds a wide-range of applications in medicine, cosmetics, and nutraceuticals because of excellent viscoelasticity, high moisture retention capacity, high biocompatibility and non-toxicity. HA has been recently produced in industrial scale by Streptococcal species. Streptococci are nutritionally fastidious lactic acid bacteria and cannot synthesize some amino acids. Therefore, it is necessary to study and select some commercial culture media for their growth. In this study, HA production and hyaluronidase activity of S. zooepidemicus ATCC 43079 in three culture media were investigated. Regarding the detrimental effect of this enzyme on HA amount, 6-O-Palmitoyl-L-ascorbic acid as hyaluronidase inhibitor was added to culture medium during fermentation. The effect of three variables consisted of glucose concentration, yeast extract concentration and medium pH each at 3 levels were considered and (response surface methodology (RSM) was used for statistical design of experiments to study the HA production by this strain. The results showed that maximum HA production was obtained when glucose concentration, yeast extract concentration and pH were 21.2 g L^-1, 43.6 g L^-1 and 6.6, respectively. Under optimum conditions, HA was produced as 370±15 mg L^-1 which was ~150% more than of HA concentration in basal medium (150±10 mg L^-1) and productivity reached 56.74 g L^-1 h^-1 that was increased 2 fold compared to central point.

Abstract Background and Objective: Polyhydroxyalkanoates (PHAs) are polymers with biodegradable and biocompatible properties that are produced by some bacteria. In the present study, petroleum sediments were applied to screen PHA-producing bacteria. Method: The industrial culture medium of petroleum effluent was used as a low-cost and economical medium for isolating and identifying the superior PHA-producing strain. Finally, the chemical and physical properties of the extracted biopolymer were investigated by Fourier-transform infrared spectroscopy, differential scanning calorimetry, and proton nuclear magnetic resonance. Results: In general, 11 out of 76 isolated bacterial strains could produce biopolymers among which, the Sb8 strain was selected as the best PHA-producing strain in the industrial medium with the cell dry weight of 44.13% and 1.2 g/l in 27 h. This strain was identified as Citreicella thiooxidans by sequencing determination. Eventually, the results of physicochemical analyses revealed that polyhydroxybutyrate (PHB) was the extracted biopolymer. Conclusion: The present study is the first report on PHB production by Iranian native Citreicella thiooxidans strain by focusing on identifying and separating producing bacteria, as well as determining the type of the produced biopolymer and the production capability in a low-cost culture medium of the petroleum effluent. Considering the production of the biopolymer with a relatively high yield percentage without adding any supplement to the petroleum effluent medium, the isolated wild strain has the potential to produce PHB.

Abstract Biosurfactants are produced by microorganisms. Surfactin is one of the main lipopeptide biosurfactants produced by different species of Bacillus subtilis. This study aims to analyze the effect of starch-coated Fe⁰and Fe³⁺nanoparticles on the biosurfactant production of Bacillus subtilis. Out of 70 soil samples, 20 Bacillus were isolated and genome sequenced by biochemical methods and 16S rRNA gene. Quantitative and qualitative screening methods were used to isolate and detect biosurfactant production. For the aim of this study, 61 and 63 (Bacillus subtilis subsp. Inaquosorum) were selected. Then, hemolytic activity, surfactant production and reduction of surface tension in Minimal Salt Medium containing Fe⁰ and Fe³⁺ nanoparticles were examined after 48h, 72h and 96h of culture. The binding of the nanoparticles to the surfactant was confirmed by SEM. Strain 61 was the best bacterium and Fe³⁺ was the best nanoparticle and it was cultured. The results were compared with the results of non-nanoparticle bioreactor. Surfactin from strain 61 culture in the Fe³⁺ nanoparticle bioreactor after 72 hours of growth showed higher production than the same strain culture after 72 hours without Fe³⁺, if continuing the research, this strain can be commercialized in the future.

Abstract Coenzyme Q₁₀ (CoQ₁₀) is a component of the respiratory chain that is responsible for generating energy by transmitting electrons. Today, due to the increasing demand for CoQ₁₀, its production is increasing. In this study, the effect of extract containing of carotenoid from bell pepper as a precursor was investigated on CoQ₁₀ production by Gluconobacter japonicus FM10. For this purpose, at first the total carotenoid was extracted from four colors of bell peppers and then the minimum inhibitory concentration of these extracts was measured. In the next step, the effect of extracts was investigated on CoQ₁₀ production in two phases of the exponential and stationary. The results showed that CoQ₁₀ production was increased in the presence of the bell pepper extract (4.1 mg / L in the presence of red bell pepper extract). In fact, 1.5 times more than when no extract was added. Adding red pepper extract in the exponential phase also increased CoQ₁₀ to 4.9 mg / L, while adding it in the stationary phase did not affect CoQ₁₀ increasing. Therefore, it can be concluded that the carotenoid in bell pepper extract increase the production of CoQ₁₀ by affecting cell growth and increasing it. Therefore, the carotenoid-extract of bell pepper can be introduced as a suitable precursor to increase CoQ₁₀ production.