The methylotrophic yeast Pichia pastoris is a well-established expression host, which is often used in the production of protein pharmaceuticals. This work aimed to evaluate the effect of various concentrations of ascorbic acid in mixed feeding strategy with sorbitol/methanol on productivity of recombinant human growth hormone (r-hGH). The relevant concentration of ascorbic acid (5, 10, or 20 mmol) and 50 g/L sorbitol were added in batch-wise mode to the medium at the beginning of induction phase. The rate of methanol addition was increased stepwise during the first 12 h of production and then kept constant. Total protein and r-hGH concentrations were analyzed and the results compared with sorbitol/methanol feeding using one-way analysis of variance. Moreover, an effective clarification process using activated carbon was developed to remove process contaminants like pigments and endotoxins. Finally, a three-step chromatographic process was applied to purify the product. According to the obtained results, addition of 10 mmol ascorbic acid to sorbitol/methanol co-feeding could significantly increase cell biomass (1. 7 fold), total protein (1. 14 fold), and r-hGH concentration (1. 43 fold). One percent activated carbon could significantly decrease pigments and endotoxins without any significant changes in r-hGH assay. The result of the study concluded that ascorbic acid in combination with sorbitol could effectively enhance the productivity of r-hGH. This study also demonstrated that activated carbon clarification is a simple method for efficient removal of endotoxin and pigment in production of recombinant protein in the yeast expression system.

Kluyveromyces marxianus is a yeast species with various industrial applications. It's known for its ability to metabolize a wide range of substrates, including lactose, xylose, and cellobiose, which makes it useful in various biotechnological processes. In order to Design of Experiment (DOE) and design an optimized method for extracting and purification of mannoprotein using three homogenization, alkalinity, and bio-emulsifier extraction methods, as well as model data at three levels based on three factors: acidity, temperature, and the mannoprotein extraction method, this study looked at the growth of the yeast Kluyveromyces marxianus (IBRC-M 30114) in a 30-L fermentor to determine its optimized yield. Mannoprotein was extracted (in 27 runs with 3 parts) using QUALITEK-4 software and the Taguchi method. In the designed stage, various temperatures (25, 30, and 35 °C) and pHs (2, 5, and 7) were used in the homogenization, alkaline, and bio-emulsifier methods. The growth of the yeast K. marxianus in a fermenter (bioreactor) showed that the maximum biomass was obtained from the scale increase inside the reactor. This indicated that the maximum fermentation biomass 34.02 (g/L) was obtained from K. marxianus in 30 h at pH 4.6, 29 °C, 500 rpm, oxygen 19.7, inlet air volume 1 vvm3, and 36.6 DO. The maximum amount of mannoprotein 8.243 (mg 100 m/L) from 10 (g/L) yeast biomass was extracted by the alkaline method with pH 5. In the bio-emulsifier method, the mannoprotein extraction was maximized at pH 7. The homogenization approach fared better than the alkaline method overall in terms of performance. In contrast, the alkaline method outperformed the other two methods homogenization and bioemulsifier in terms of volume or quantity. Mannoproteins play important roles in various biological processes and have several applications in different industries. Mannoproteins have potential applications in drug delivery and as carriers for bioactive compounds due to their biocompatibility and ability to interact with cells and tissues.

The study investigated the efficiency of biodiesel conversion from jatropha oil-based free fatty acid using an acid-based catalyzed transesterification bioprocess. The maximum Jatropha biodiesel yield was 80% in a 1-hour reaction using a 0.03:1 acid catalyst to oil and a 2:1 alcohol-to-oil ratio. At the same time, the optimum biodiesel yield was in a 2-hour reaction for step 2 by using a 0.03:1 ratio of base catalyst to oil and a 5:1 ratio of alcohol to oil. The Fourier Transform Infrared Spectrometer analysis of Jatropha Biodiesel (JB) revealed a methyl peak (O-CH3) at 1436.07 cm-1, indicating compatibility with pure mineral diesel, high speed (1295.67rpm), brake horsepower(30.6906KW), mechanical efficiency (53.10%), and lower specific fuel consumption (15.5879 mL/KW. compared with other Jatropha biodiesel blends.