The bioconversion of lignocellulose into monosaccharides is critical for ensuring the continual manufacturing of biofuels and value-added bioproducts. Enzymatic degradation, which has a high yield, low energy consumption, and enhanced selectivity, could be the most efficient and environmentally friendly technique for converting complex lignocellulose polymers to fermentable monosaccharides, and it is expected to make cellulases and xylanases the most demanded industrial enzymes. The widespread nature of thermophilic microorganisms allows them to proliferate on a variety of substrates and release substantial quantities of cellulases and xylanases, which makes them a great source of thermostable enzymes. The most significant breakthrough of lignocellulolytic enzymes lies in lignocellulose-deconstruction by enzymatic depolymerization of holocellulose into simple monosaccharides. However, commercially valuable thermostable cellulases and xylanases are challenging to produce in high enough quantities. Thus, the present review aims at giving an overview of the most recent thermostable cellulases and xylanases isolated from thermophilic and hyperthermophilic microbes. The emphasis is on recent advancements in manufacturing these enzymes in other mesophilic host and enhancement of catalytic activity as well as thermostability of thermophilic cellulases and xylanases, using genetic engineering as a promising and efficient technology for its economic production. Additionally, the biotechnological applications of thermostable cellulases and xylanases of thermophiles were also discussed.

Microbial transformation of cholesterol produces various steroid drugs and intermediates, such as cholest-4-en-3-one (C4EO), which is an important intermediate of hormone steroidal drugs. Cholest-4-ene-3,6-dione (CEDO) is another product of cholesterol biotransformation, with better medicinal value than cholest-4-en-3-one. It is indicated to improve fat metabolism, resistance to tumors and essential in the treatment of nerve injuries. This study proceeded using Burkholderia cepacia ZWS15, which is known to produce enzymes to transform cholesterol. Organic solvents were chosen to increase the solubility of the substrate cholesterol and the conversion of the product, and the organic solvent affects the mechanism of product conversion and cell membrane permeability. The use of organic solvents in this study prompted shifts in the composition of fatty acids in the cell membrane, inducing the production of more unsaturated fatty acids and reduction of saturated fatty acids. The alkenone products generated after transformation of cholesterol were isolated.

Cholesterol biotransformation is a very crucial process industrially, as it guarantees the production of high medically/clinicallyvalued products in fewer uncomplicated steps, compared with the classical or traditional synthesis. The biotransformation of cholesterol also yields a wide range of products that can be useful in many ways, even in the pharmaceutical industries. Theenzymes from the microbes used to facilitate this transformation may have the capacity to be reused. This paper focuses on theuse of B. cepacia to produce two main products; cholest-4-en-3-one and cholest-4-ene-3,6-dione. This paper also centers attentionon the use of organic solvents and gives recommendations for the development of bioreactors to give room for even highly useful but harmful organic solvents to be employed without harmful consequences to the environment or the users. Keywords: Cholest-4-en-3-one, organic solvents, Burkholderia cepacia, Cholesterol transformation, sterols

Ethanol fermentation is a biological procedure which converts sugars such as glucose, fructose, and sucrose into cellular energy, producing ethanol and carbon dioxide as by-products. Since yeasts perform this conversion in the absence of oxygen, alcoholic fermentation is generally considered to be an anaerobic process. Ethanol fermentation has many uses, including the production of alcoholic beverages, the production of ethanol fuel, and bread making. The increasing demand for biofuels around the globe has also prompted the necessity to seek other means to meet the demands. In this review, the general ideologies, methodologies, general chemistry and biochemistry and conditions of the production of ethanol by fermentation engineering using Saccharomyces cerevisiae are highlighted. The quest to reduce pressure on staple foods has necessitated the attention now given to the use of lignocellulose biomass, despite the complexity of the process. It concludes by suggesting ways to improve yield and commercialization of the use of lignocellulosic biomass for ethanol fermentation.