Background: Rhodosporidium strain, a well-known oleaginous yeast, has been widely used as a platform for lipid and carotenoid production. However, the production of squalene for application in lipid-based biofuels is not reported in this strain. Here, a new strain of Rhodosporidium sp. was isolated and identified, and its potential was investigated for production of squalene under various cultivation conditions. Results: In the present study, Rhodosporidium sp. DR37 was isolated from mangrove ecosystem and its potential for squalene production was assessed. When Rhodosporidium sp. DR37 was cultivated on modified YEPD medium (20 g/L glucose, 5 g/L peptone, 5 g/L YE, seawater (50% v/v), pH 7, 30 °C), 64 mg/L of squalene was produced. Also, squalene content was obtained as 13.9% of total lipid. Significantly, use of optimized medium (20 g/L sucrose, 5 g/L peptone, seawater (20% v/v), pH 7, 25 °C) allowed highest squalene accumulation (619 mg/L) and content (21.6% of total lipid) in Rhodosporidium sp. DR37. Moreover, kinetic parameters including maximum specific cell growth rate (μ_max, h⁻¹), specific lipid accumulation rate (q_p, h⁻¹), specific squalene accumulation rate (q_sq, h⁻¹) and specific sucrose consumption rate (q_s, h⁻¹) were determined in optimized medium as 0.092, 0.226, 0.036 and 0.010, respectively. Conclusions: This study is the first report to employ marine oleaginous Rhodosporidium sp. DR37 for accumulation of squalene in optimized medium. These findings provide the potential of Rhodosporidium sp. DR37 for production of squalene as well as lipid and carotenoids for biofuel applications in large scale. Graphic

Aims: Wheat performance under both Irrigated and dry land areas is affected by salinity and decreased. Like other plants, wheat cultivars try to indicate salt resistance through biochemical, physiological and morphological changes. In this study, responsive proteins in wheat leaves under salt stress were investigated by proteomics technique. Study Design: Factorial experiment based on a randomized complete block design Methodology: In this research, tolerant (Roshan) and sensitive (Ghods) cultivars were treated by 200mM salinity during 17 days. A proteomic technique was used to study proteins of leaf. Proteins of the leaves were extracted by TCA–acetone, and separated by two-dimensional gel electrophoresis at pH 4–7. Results: 200 repeatable spots were identified by using Melanie software and analyzed statically. 24 and 12 responsive spots were identified by using MALDI TOF-TOF mass spectrometry in tolerant and sensitive cultivars respectively. 5 responsive proteins were overlap between both cultivars. In tolerant cultivar, Expression of 19 spots was increased and expression of 5 spots was decreased. All the identified proteins are involved in the regulation of carbohydrate, energy and nitrogen metabolism, photosynthesis related proteins, ROS scavenging proteins, signaling related protein, transporters and chaperon. But, all identified proteins except one of them in sensitive cultivar were down regulated under salt stress. Conclusion: Based on this study, salt tolerant cultivar could alleviate salt stress. But salt sensitive cultivar couldn’t tolerate salinity and it seems that salt stress have destructive effects on its proteins. In other words, protein compositions of salt sensitive cultivar are more deeply damaged by salt stress than salt tolerant cultivar and protein decay could be a marker of the sensitivity of the concerned cultivar.