---

Today, many studies are doing to identify the lipolytic microorganisms because of the important role of them in the production of microbial lipases. Oilseed meals are a good place to achieve these microorganisms. In this field, yeasts are more important in comparison with other microorganisms. In this study, we isolated 27 types of fungi from Yazd sesame meal. After the evaluation of macro and micro morphological features, it was identified that 16 of them were from yeast group. Lipolytic yeasts were screened using Tween 80 agar medium and were identified to genus and species by colony and cell morphology observations and evaluation of fermentation reactions and the use of carbon and nitrogen sources. 4 lipolytic  screened  yeasts were included Sporidiobolus pararoseus, Sporobolomyces salmonicolor, Cryptococcus albidus and Yarrowia lipolytica .The ratio of areola diameter to the well diameter was  between 2.314 – 2.714. S. pararoseus showed  the maximum ratio of areola to well diameter (2.714) .Lipase activity of these four types of yeasts was measured in submerged cultures with Cezepek Dox medium for 7 days at 30 °C and 200 rpm by using of photometry method and p-nitrophenyl palmitate substrate. Lipase activity range was between 0.866 – 4.333 U/ml, and Cryptococcus albidus had the highest lipase activity 4.333 U / ml, while it showed the least biomass growth among other yeasts (OD= 0.577). Yarrowia lipolytica showed lipase activity of 3.466 U/ml and also, the highest biomass growth OD =0.806.  

---

Yarrowia lipolytica is unusual yeast that has the ability to produce important metabolites such as lipase enzymes. Lipase enzyme has many applications in different industries including manufacturing of detergents, food industry, pharmacy, fuel and etc. In this paper, we studied the lipase enzyme produced by the yeast under different treatments of nitrogen sources such as yeast extract, peptone, soybean meal, sesame meal and sesame meal extracts on the medium of Czapek Dox Broth. Selected treatments of nitrogen resources include treatment solution (100%), solution (50%) containing with sesame cake extract (3.6%), solution (50%) containing with sesame cake extract (3.6%) in distilled water, solution (50%) containing with yeast extract (3.6%) in distilled water and solution (50%) containing with peptone (3.6%) in distilled water on the medium (CDB). Fermentation time levels are considered 3, 4 and 5 days. Among examined treatments, Treatment solution (50%) containing with sesame cake extract (3.6%) on the medium (CDB) showed the highest lipase activity (91.5900±0.56241 and 67.5200 ± 0.01000 enzyme units, respectively) in the fourth day of incubation with stirring speed (120 rpm) and temperature (30 °C). The results show use of sesame cake extract increases lipase activity more than use of yeast extract and peptone at the level of 5%. Also, statistical analysis of resulted data showed use of sesame cake extract increases lipase activity significantly at 5% level in comparison with yeast extract and peptone.

---

The lipase is used broadly in different industries such as food, drug, petroleum and detergent industry due to the catalyst ability of wide range of conversion reactions such as hydrolyzed, esterification and transesterification . Yeasts are one of the main generators of lipases. In this paper, we use RSM and CCD in order to examine the effect of PH (5.5-7.5), time incubator (3-7days) and sesame meal extracts added to experimental medium (0-100%) on lipase generation and activity, generated biomass of Cryptococcus albidusand optimization of lipase generation process and generated biomass. The results showed that the percentages of sesame meal extracts added to experimental medium and time incubator are the most effective factors on lipase generation and activity and amount of generated biomass, respectively. Based on conducted experiments, optimized conditions of lipase generation and amount of generated biomass are determined PH 5.56 time incubator 7 days and percentages of sesame meal extracts added to experimental medium 100 percent in order to achieve maximum lipase activity (98.96 unit enzyme) and cell dry weight (1.14 gram per 100 mili liter medium).