Peels of sweet potato (Ipomoea batatas) were buried in the soil for 14 days and the isolates associated with the degradation of the peels were obtained using standard microbiological procedures. The bacterial isolates obtained were screened for amylolytic and cellulolytic activities under different pH and temperatures as parameters and optimized for enzyme production. Sixteen (16) bacterial isolates were obtained and characterized and screened for amylase and cellulase production. Bacillus pumilus has the highest frequency of occurrence (18.75%) followed by B. subtilis (12.50%). After 24 to 48 h of incubation, B. pumilus produced highest concentration of amylase at 55°C, pH 6 (5.4 U/mL) while B. subtilis had the best cellulase production of 0.75 U/mL at 55°C, pH 7. B. pumilus and Bacillus subtilis produced the highest amylase and cellulase concentrations and seem to be the potential sources of these enzymes for industrial application.

Bioethanol production from monomeric sugar is performed by several yeasts. But there are several limitations associated with yeast strains such as their low tolerance to ethanol, toxic inhibitors, and high sugar concentration. Genetic and metabolic engineering of potential yeast strains can overcome the above limitations. The present article summarized current genetic and metabolic engineering approaches for the development of yeast strain for efficient ethanol production. The review systematically examined bioethanol generations based on substrate utilization, criteria for strain selections, strategies for strain improvements including randomized mutagenesis, genetic engineering, metabolic engineering, genome editing, whole genome (re)sequencing, promoter engineering, quantitative trait locus analysis, protein engineering, and evolutionary engineering. Different fermentation technologies employed in hydrolysate fermentation including low gravity (LG), high gravity (HG), and very high gravity (VHG) as well as challenges of yeast strains development and its future prospect have been critically evaluated in this article. Significant engineering efforts are imminent for yeast‐based second‐generation biofuel to leave a demonstration phase through strain improvement and become economically competitive with fossil fuel. Practical Applications This is a comprehensive review of yeast strain development for bioethanol production. The readers should be able to acquire some basic knowledge on: The accompanied substrates for bioethanol generations as well as the technologies and challenges behind them. The criteria to consider in selecting yeast strain for bioengineering development. Different strategies and their reported applications employed in yeast strain development including randomized mutagenesis, genetic engineering, metabolic engineering, genome editing, whole genome (re)sequencing, promoter engineering, quantitative trait locus (QTL) analysis, protein engineering, and evolutionary engineering. Challenges and merits of different fermentation technologies employed in hydrolysate fermentation including LG, HG, and VHG. Possible challenges to encounter in developing yeast strain for bioethanol production. Desirable traits to consider in the selection and development of yeast strains for bioethanol production.

The synergy between enzyme and nanotechnology (Nano-biocatalysts) has greatly surfaced as one of the promising biomaterials fabricated by synergistically incorporating advanced nanobiotechnology. The incorporation of enzymes into nanotechnology is of great significance to make nanomaterials rarely harmful to the environment. However, the unique/specific physicochemical characteristics and supramolecular nature ascribed to functional nanostructures (nanomaterials), have made them novel, interesting to be exceptional matrices for the creation of nano-biocatalysts. These possess a lot of prospects in improving the enzyme stability, function, efficiency, kinetic characteristics, vulnerability to diffusional constraints, and engineering performance in bioprocessing. Hence, the developed nano-biocatalyst conceal an exceptional property with a great potential application in diverse field. This review covers a wide range of nanotechnology and enzyme technology (nano-biocatalysts) including different mechanisms, strategies in nanomaterials enzyme immobilization, and various nanocarriers as well as their recent developments in controlling enzyme activity. The vast potential application of nano-biocatalysts in various fields including food, pharmaceuticals, biofuel, and bioremediation have been discussed.

Introduction: Amylase, cellulase and protease are known for hydrolyzing starch, cellulose and protein respectively and these enzymes can be produced by microorganisms. A single bacterium with potential of producing amylase, cellulase and protease will be an organism of high industrial value. Aims: This work aimed at isolating bacteria that will be able to produce three extracellular enzymes (amylase, cellulase and protease). Methodology: Soil samples were collected from eight different locations within Ajayi Crowther University, Oyo Town, Nigeria. Bacteria were isolated from these soil samples and were identified using morphological and biochemical characteristics. Isolated bacteria were screened for their ability to produce amylase, cellulase and protease on plate and enzymes’ relative activities on plate were determined. Results: Forty two bacteria were isolated from soil samples and identified to belong to the Genera Bacillus (30), Enterobacter (6), Klebsiella (3) and Staphylococcus (3). Eight (19%), Eleven (26%) and Nineteen (45%) out of 42 isolated bacteria were able to produce amylase, cellulase and protease on plate with relative activities ranging from 1.25 – 2.88, 1.39 – 4.50 and 1.13 – 5.17 respectively. All the eight amylolytic isolates (Bacillus species (5) and Enterobacter species (3)) were able to produce the three enzymes (amylase, cellulase and protease). Conclusion: Eight bacteria with ability to produce three enzymes (amylase, cellulase and protease) were isolated from soil samples and could be further employed in enzyme-producing industries.

Maize straw (MS) is a lignocellulosic substrate that constitutes huge wastes in the environment. This work aimed to pretreat MS with mushroom alone as a biological agent, and with NaOH prior to mushroom treatment (combined chemical and biological), and subsequently converting the released reducing sugars (RS) to ethanol using Saccharomyces cerevisiae. MS was degraded by Pleurotus ostreatus (PO) and Lentinus squarrosulus singly and in combination for 35 d. Samples were collected every 7 d from the treated straw to determine the RS content. Moreover, MS samples were pretreated with NaOH prior to degradation by the selected mushroom (combined pretreatment), and then their sugar profiles were determined using High-performance liquid chromatography (HPLC). The RS recovered from the degraded MS samples were fermented using 2 molecularly-identified S. cerevisiae strains. The highest RS contents (16.79 mg/ g) were recorded when MS was pre-degraded by PO for 21 d compared to Lentinus squarrosulus (16.55 mg/ g), and with the consortium of the two fungal cultures (16.36 mg/ g). However, MS pretreated with NaOH and Pleurotus ostreatus gave better yield of RS (17.38 mg/ g), than treatment with Pleurotus ostreatus (16.79 mg/ g) alone. The sugar profiles of the NaOH-PO-pretreated MS (mg/ 100 g) included; glucose (850.60); xylose (837.04), fructose (754.29), arabinose (502.76), ribose (2.066×10 -4 ) and rhamnose (3.552×10 -5 ). The fermenting yeasts were molecularly identified by sequencing of ITS region as S. cerevisiae SA01 and S. cerevisiae SA02, and assigned Accession no. of MK038975 and MN491900, respectively. Equal concentration of bioethanol (1.58 g/ l) was recorded in PO and in NaOH-PO-pretreated MS, which were fermented by S. cerevisiae SA01. Accordingly, MS can be utilized as a substrate for fermentation and then bioethanol production.