آزاده عبدلی

Excessive consumption of fossil fuels and excessive production of CO2, in addition to problems related to the golabal warming cause air pollution. This has attracted more attention to biodiesel production. Among the benefits of biodiesel production is that when it burns no net CO2 is emitted. Therefore, finding a biological way to produce biodiesel has not only economical value but also it is valuable in terms of environmental aspects and impact on human health. The goal of this study was application of oleaginous yeast for biodiesel production and optimization of production process.
In this study, the oleaginous fungus Mortierella alpina with high capacity of lipid production was used for microbial oil production. After analyzing the produced oil by gas chromatography-mass spectrometry (GC-MS), its potential for biodiesel production was evaluated. Also optimization of medium condition for increasing lipid production was done. The optimized condition was used in a semi laboratory (pilot-scale) fermentor I order to evaluate lipid production.
Findings: The evaluated fungal strain had the highest lipid production of 10.9g/L. This strain had biodiesel yield of 71% and the highest fatty acid was oleic acid with amount of 38%.
The lipid composition in this fungus has a high similarity with plants oil and can compete with plants lipid for biodiesel production and is valuable from economical point of view.

Microbial oil has lots of similarity to the plant’s oil; the only difference between them is that microbial oil is rich in unsaturated fatty acids. This oil can be used in pharmaceutical industry for technical purposes or as edible oil in food industry. The purpose of this study was to increase lipid production and the amount of unsaturated fatty acids in oleaginous yeasts by mutagenesis. In this study, optimization of lipid production in the yeast ,Yarrowia lipolytica, was done using ultraviolet random mutation and screening was done with the inhibitory effect of cerulenin on lipid synthesis. Mutants that had normal growth in the presence of cerulenin were selected as superior strains for further investigations. Lipid production in mutants and wild strains were compared after incubation period. Then, the mutant with significant increase in lipid production was selected. The best mutant had increasing of 50% and 30% in lipid production and growth yield, respectively. Also, Linoleic acid was increased after mutation. The composition of fatty acids in the lipid profile of the evaluated yeast did not change a lot after mutation. Of course, unsaturated fatty acids were increased, so this technique was very effective to improve lipid production. Cerulenin used as an effective screening technique in this study and paved the way for the isolation of superior mutants.

Application of microbial lipids as an alternative source of oil was considered in the early years of 20th century. Microbial oil rich in essential polyunsaturated fatty acids (omega series) is one of the important aspects of single cell oil production. By development of technical - economical processes and also by optimization of microbial lipid production, high efficiency of microbial lipid can be provided. In this study, two standard yeast strains and four native strains were evaluated for potential of lipid production. Optimization of lipid production in these strains was carried out using design of experiments and factors affecting lipid synthesis in these strains were compared. Obtained oil was analyzed using Gas Chromatography-Mass spectrometry (GC-MS). Among the standard strains, Yarrowia lipolytica DSM8218 and the native strain Cryptococcus albidus had maximum lipid production rate of 7.65 g/L and 11.81 g/L, respectively. Application of Taguchi method was so effective in optimization of microbial lipid production and significantly increased production in evaluated strains. These lipids have potential for applications in food and pharmaceutical industries.

The application of microorganisms in the production of economically valuable products has attracted a great attention in recent years. These valuable materials such as single cell oil and poly-alcohols have potential for application in various industrial fields. Single cell oil in biodiesel production and poly-alcohols such as xylitol in the food and pharmaceutical industries, are valuable. In this study high production of SCO was evaluated and analyzing of SCO was done by FTIR spectroscopy. In addition, xylitol production by the yeast, in the media containing xylose was done and xylitol was analyzed by using colorimetric method. Optimization of microbial oil and xylitol production was done by Taguchi method and valuable results were obtained. This strain was reached to SCO production and dry biomass of 10.21 g/L in optimum condition including 100 g/L glucose, 72 h incubation time, pH = 5, temperature of 25 ºC and rpm=180. In addition, in the medium with 140 g/L of xylose, xylitol production was 54.99 g/L. The results of this study can show that there are native yeasts with high potential of producing valuable materials which can be directed to produce the desired products by providing appropriate medium condition.

Since the wound infections caused by gram positive and negative bacteria are very common, application of Nanocrystalline silver in wound healing bands is recently of one of points of research interests. The epithelization effect and control of wound infection are the most important factors for selection of disinfecting factors in these bands. This study was performed to produce nanocrystalline silver bands and to investigate their efficiency on control of selected gram positive and negative bacteria.
In this study, silver nanocrystalline dressing was produced using nylon dressing and silver ions. Thereafter, we evaluate its antibacterial effect against Staphylococcus aureus and Escherichia coli. The experiments were designed based on Taguchi method for investigation different parameters on antimicrobial effect of silver dressing.
The silver dressing showed an impressive effect on inhibition of the growth of mentioned bacteria and leads to the inhibition zone diameter of 5.5 cm around the dressing pieces. AgNO3 was the most important parameter in determination of the antimicrobial effect of silver dressing (approximately 65% efficiency).
Silver nanocrystalline dressing was effective on inhibition of microorganisms growth. Furthermore, application of Taguchi method was highly effective in optimization process of this investigation.

Application of microbial lipid as the superseding source of oil for human utilization was regarded in the first years of 20th century. One of the important aspects of single cell oil production is producing of microbial lipid rich in unsaturated fatty acids. Another importance of microbial oil is its application in biodiesel production, so isolation of oleaginous yeast with high potential of lipid production and efforts for increasing lipid content of them has great importance. In this investigation the goal was increasing lipid production of Rhodotorula musilaginosa using UV mutation technique. For this purpose at first oleaginous yeast Rhodotorula musilaginosa was isolated. Produced oil was analyzed by FTIR spectroscopy and gas chromatography - mass spectrometry (GC-MS) technique. The strain was identified by PCR method, after that the effect of UV mutation on its lipid yield was evaluated. For screening of mutated colonies with higher potential of lipid production, replica-printing technique was used. During different mutations one of the screened colonies with this technique had increasing in lipid content from 33.7% to 58.62% which was equal to 3.05 g/l increasing in lipid yield. These results show that there are valuable native strains with potential of increasing of lipid production using mutation and can be used in different industrial fields such as biodiesel production.

Aim and Micro-organisms that can accumulate lipid more than 20% of their biomass are called oleaginous. Microbial lipid has high similarity with plant''s oil; the only difference between them is that microbial lipids are rich in polyunsaturated fatty acids. Synthesized lipid by the yeast has potential of using in pharmaceutical industry for technical purposes or as nutritional supplements. The importance of microbial triacylglycerols is the high amount of polyunsaturated fatty acids with 16 and 18 atoms of carbon which is important from nutritional point of view. In this study the amount of lipid production by standard and native yeast strain on glucose، xylose and glycerol as carbon sources was evaluated. After selection the type of carbon source، the effect of MgSO4 on lipid production was investigated by one factorial method. After these steps، optimization of other parameters such as carbon and nitrogen concentration، temperature، agitation rate، pH and time of incubation was done with Taguchi method. FTIR Spectroscopy was used for analysis and verification of produced oil، in this study. The yeasts Yarrowia lipolytica DSM70562 and geotrichum BL have reached to lipid production of 7. 35 g/L and 5. 35 g/L، respectively. The most effective factor in optimization process of evaluated yeasts was the concentration of carbon source. This factor for the evaluated standard and native yeasts strains was 41. 37% and 63. 57%، respectively. The results of lipid analysis by FTIR Spectroscopy technique showed remarkable similarity between extracted oil from yeast strains and related standard (triolein). According to the results obtained by Taguchi design، lipid production in evaluated standard and native yeasts increased 2. 94 g/L and 1. 22 g/L، respectively after optimization. This shows the high efficiency of using Taguchi design in optimization of medium condition. So by using Taguchi design we can do the optimization process، which is the necessary and effective step of all industrial process for increasing productivity and reducing the costs، as best as possible.

Microbial lipid composition is similar to the oil obtained from plants and animals. Although vegetable oils were originally used for producing biodiesel, high costs of the process encouraged industries to use  microbial lipids as biodiesel sources. This study was conducted to isolate yeast strains with high lipid productivity, to optimize the extraction process of produced lipid and to convert the lipids to biodiesel.
In this study, after isolation of the yeast Rhodotorula, the productivity of microbial lipid in nitrogen limited condition, rice straw and wheat bran hydrolyzate was evaluated. The products were analyzed based on Gas Chromatography-Mass Spectrometry technique (GC-MS). The lipid production was optimized by two techniques (one factorial and Taguchi method) and the results were compared. At the end, the yeast strain was identified using polymerase chain reaction (PCR) techniques.
The strain isolated from this study was identified as Rhodotorula musilaginosa. The strain had high lipid production and dry biomass of 10.97 g/l and 18.84 g/l in optimized conditions, respectively. The highest fatty acids were Palmitic acid (18.51%) and Oleic acid (67.29%).
The results obtained in this study indicate that there are valuable native strains in our country that they can be used in different industries , especially biodiesel production.

In this study, the factorial optimization method and designing of experiments by the Taguchi method were applied for optimization of lipid production by a native oleaginous yeast Rhodotorula spp. strain Yr2. The factors investigated were temperature, aeration, nitrogen source, carbon source, pH and incubation time. Based on results obtained by factorial optimization method, maximum production (8.9 g/L) was achieved with ammonium sulfate (1g/L) as nitrogen source, glucose (90g/L) as carbon source, at 25°C, aeration speed of 150rpm, incubation time of 96h and at pH 6. Whereas using the Taguchi method, the predicted optimal conditions were ammonium sulfate (1g/L) as nitrogen source, glucose (75g/L) as carbon source, at 25°C, aeration speed of 150rpm, incubation time of 72h and at pH 6.5. The amount of lipid production predicted by the software under these conditions was 11.052 g/L. and in the predicted case, 95% of the predicted value was achieved (10.49 g/L). The ANOVA results obtained with the Taguchi design showed that time; the amount of carbon, temperature, pH and nitrogen levels, respectively had the highest effects on lipid production in descending order. In conclusion, the application of the Taguchi method in compared with one factorial method led to increased lipid production by 1.59 g/L or 18%.