No abstract

No abstract

No abstract

Current research in industrial microbiology and biotechnology focuses on the production of biodegradable microbial polymers as an environmentally friendly alternative to still dominant fossil-based plastics. Microbial polymers have an extensive biotechnological potential and are already widely used in a variety of fields ranging from medicine to technology. However, their increase in production and wider use is hampered by the high cost of raw materials and therefore requires a focus on cheaper inputs, including dairy by-products and waste such as cheese whey (CW). This is an environmentally unfriendly by-product of milk processing and reducing it would also reduce the risk of environmental pollution. This review summarises current knowledge on the use of CW and derived products to obtain commercially important microbial polymers, including information about producer cultures, fermentation techniques and methods used, composition of culture medium, cultivation conditions and productivity of bioprocesses. The main methods and applications of cheese whey pre-treatment are also summarised.

The non-conventional yeast Kluyveromyces marxianus is an emerging industrial producer for many biotechnological processes. Here, we show the application of a biomass-linked stoichiometric model of central metabolism that is experimentally validated, and mass and charge balanced for assessing the carbon conversion efficiency of wild type and modified K. marxianus. Pairs of substrates (lactose, glucose, inulin, xylose) and products (ethanol, acetate, lactate, glycerol, ethyl acetate, succinate, glutamate, phenylethanol and phenylalanine) are examined by various modelling and optimisation methods. Our model reveals the organism's potential for industrial application and metabolic engineering. Modelling results imply that the aeration regime can be used as a tool to optimise product yield and flux distribution in K. marxianus. Also rebalancing NADH and NADPH utilisation can be used to improve the efficiency of substrate conversion. Xylose is identified as a biotechnologically promising substrate for K. marxianus.