OBJECTIVE: The main objective of this study was to explore oleaginous yeast, Yarrowia lipolytica isolated from soil and optimization of culture conditions and medium components to obtained better quality microbial oil for biodiesel production.

METHODS: Fifty yeast strains were isolated from soil from different regions of Lahore and eleven of them were selected for oil production. The isolated yeast colonies were screened to further check their lipid producing capabilities by the qualitative analysis. Five yeast strains were designated as oleaginous because they produced more than 16% of oil based on their biomass. To estimate the total lipid content of yeast cells, the extraction of lipids was done by performing the procedure proposed by Bligh and Dyer. The transesterification of yeast oils was performed by using different methods. There were three different strategies customized to transesterifying microbial oil using base catalyzed transesterification, acid catalyzed transesterification and enzyme-based transesterification. After completion of transesterification, sample was used for fatty acid methyl esters (FAMEs) were analyzed by gas-chromatograph with ionization detector type MS.

RESULTS: The isolate IIB-10 identified as Yarrowia lipolytica produced maximum amount of lipids i.e. 22.8%. More amount of biomass was obtained when cane molasses was utilized as carbon source where it produced 29.4 g/L of biomass while sucrose and lactose were not utilized by IIB-10 and no biomass was obtained. Similarly, meat extracts showed best results when it was used as nitrogen source because it resulted in 35.8 g/L biomass of Yarrowia lipolytica IIB-10. The culturing conditions like size of inoculum, effect of pH and time of incubation were also studied. The 10% of inoculum size produced 25.4 g/L biomass at 120 h incubation time, while the pH 7 was the optimum pH at which 24.8 g/L biomass was produced by Yarrowia lipolytica IIB-10. GC-MS analysis showed that biodiesel produced by transesterification contained similar fatty acids as found in vegetable oil for this reason it is widely accepted feedstock for biodiesel production.

AIMS OF STUDY: The aim of the present study is to evaluate the repeated dose toxicity of the standardized aqueous extract administered daily for 30 days through oral administration at its effective hypoglycemia doses.

MATERIALS AND METHODS: The seeds were dried, ground and extracted in deionized water. A HPLC-photodiode array method was developed and validated for the standardization of both the hypoglycemia agents, namely bruceine D and E in aqueous extract. Both normoglycemia and streptozotocin (STZ)-induced diabetic rats were fed orally with 15, 30 and 60mg/kg body weight of standardized aqueous extract. The blood glucose was measured at 0-8h. In repeated dose toxicity, similar doses were administered orally to rats for 30 days. At the end of 30 days, the blood was withdrawn and subjected to biochemical and haematology analysis while organs were harvested for histology analysis.

RESULTS: Oral administration of standardized aqueous extract exhibited a dose-response relationship in both the normoglycemia and STZ-induced diabetic rats. Daily oral administration of 15, 30 and 60mg/kg standardized aqueous extract for 30 days to rats did not show signs to toxicity in its biochemical, haematology and histology analysis.

METHODS: The in vitro anti-TB activity of different solvent partitions of the plant materials was determined against M. tuberculosis H37Rv using a tetrazolium colorimetric microdilution assay. The phytochemical compounds in the most active partition of each plant were identified using gas chromatography-mass spectrometry (GC-MS) analysis. The effects of these partitions on the growth kinetics of the mycobacteria were evaluated over 7-day treatment period in a batch culture system. Their effects on the mycobacterial cellular integrity were observed under a scanning electron microscope (SEM).

RESULTS: The respective n-hexane partition of C. speciosus, C. citratus, and T. coronaria exhibited the highest anti-TB activity with minimum inhibitory concentrations (MICs) of 100-200 μg/mL and minimum bactericidal concentration (MBC) of 200 μg/mL. GC-MS phytochemical analysis of these active partitions revealed that majority of the identified compounds belonged to lipophilic fatty acid groups. The active partitions of C. speciosus and T. coronaria exhibited high cidal activity in relation to time, killing more than 99% of the cell population. SEM observations showed that these active plant partitions caused multiple structural changes indicating massive cellular damages.

RESULTS: The concentration of total reducing sugars was reduced by up to 64.61, 77.22 and 82.52% with increased roasting temperature at 150, 200 and 250°C for 50 min, respectively. The hydrophobic amino acids were reduced up to 29.21, 36.41 and 48.87% with increased roasting temperature at 150, 200 and 250°C for 50 min, respectively. A number of pyrazines, esters, aldehydes, alcohols, ketones, carboxyl acids and hydrocarbons were detected in all the samples at different concentration range. Formation of the most flavour active compounds, pyrazines, were the highest concentration (2.96 mg kg-1 ) at 200°C for 10 min.