Growth of yeast and production of polyhydroxybutyrate using rice wastewater

Water pollution is a critical global issue aggravated by the release of agricultural runoff, industrial effluents, and domestic sewage into the water bodies. Rice cultivation is a major agricultural activity in Bangladesh that generates substantial amounts of wastewater through the parboiling of rice. This thesis explores the innovative use of rice waste stream as a substrate for conventional yeast, Saccharomyces cerevisiae, simultaneously addressing water pollution along with fostering biodegradable polymer, Polyhydroxyalkanoates, and biomass production. Experimental methodologies are outlined encircling the expression of PHA synthase, PhaC1, and PhaC2 from Pseudomonas mendocina, an efficient cell factory for biopolymer production in cytosols and peroxisomes of S. cerevisiae. The outcome of this research showcases the successful production of polyhydroxybutyrate (PHB) in engineered S. cerevisiae cultured in oleate and YPO media. The study encompasses a multifaceted approach with an in-depth analysis of rice waste effluents, investigating their compositions and nutrient content. Analysis of the composition of rice wastewater manifests its potential as a nutrient-rich substrate, laden with organic and inorganic components and makes it an ideal resource for the growth of conventional yeast. Growth of S. cerevisiae in rice waste stream including various nutrient supplements displays the potential of rice waste effluent as a rich source of carbon and nutrients, supporting the growth and metabolic activities of yeast. Additionally, the production of biopolymers such as PHB is quantified, offering insights into the feasibility of utilising rice waste effluents as a sustainable biopolymer stock.