Cellulases are a group of hydrolytic enzymes that break down cellulose to glucose units. These enzymes are used in the food, beverage, textile, pulp, and paper and the biofuel industries. The aim of this study was to isolate fungi from natural compost and produce cellulases in submerged fermentation (SmF). Initial selection was based on the ability of the fungi to grow on agar containing Avicel followed by cellulase activity determination in the form of endoglucanase and total cellulase activity. Ten fungal isolates obtained from the screening process showed good endoglucanase activity on carboxymethyl cellulose-Congo Red agar plates. Six of the fungal isolates were selected based on high total cellulase activity and identified as belonging to the generaTrichodermaandAspergillus. In SmF of synthetic media with an initial pH of 6.5 at 30°CTrichoderma longibrachiatumLMLSAUL 14-1 produced total cellulase activity of 8 FPU/mL and endoglucanase activity of 23 U/mL whilstTrichoderma harzianumLMLBP07 13-5 produced 6 FPU/mL and endoglucanase activity of 16 U/mL. The produced levels of both cellulases and endoglucanase byTrichodermaspecies were higher than the levels for theAspergillus fumigatusstrains.Aspergillus fumigatusLMLPS 13-4 produced higherβ-glucosidase 38 U/mL activity thanTrichodermaspecies.

The production cost of cellulases is regarded as a limiting factor in the cellulosic ethanol production chain. Trichoderma and Aspergillus species were used to produce cellulases through solid-state fermentation (SSF) utilizing banana pseudostem (BPS) as a carbon source. The production of cellulases was investigated at various substrate moisture contents (65–80%), incubation temperatures (30–40 °C), substrate pre-treatment methods (3% w/v NaOH, 5% v/v H₂SO₄, and water), and with different co-culturing of microorganisms. Trichoderma longibrachiatum LMLSAUL 14-1 produced the maximum total cellulase (75 FPU/g d.s), endoglucanase (11.35 U/g d.s), and β-glucosidase (235.83 U/g d.s) activities at a 75% moisture content of the untreated BPS at 30 °C in static culture. Pre-treatment of BPS improved the production of specific enzymes. Aspergillus fumigatus LMLPS 13-4 produced more β-glucosidase (259.8 U/g d.s) when grown on acid-pre-treated BPS, whereas T. harzianum LMLBP07 13-5 produced the highest β-glucosidase activity (319.5 U/g d.s) on alkali-pre-treated BPS. Co-culturing of T. harzianum LMLBP07 13-5 and A. fumigatus LMLPS 13-4 improved the production of endoglucanase. These results suggest that banana pseudostem, a waste product of the banana industry, could be a potentially cheaper and abundant substrate for the production of the cellulase enzymes.

Banana pseudostem (BPS) is an agricultural waste with a high holocellulose content, which, upon hydrolysis, releases fermentable sugars that can be used for bioethanol production. Different pretreatment methods, namely, 3 (w/v) NaOH, 5 (v/v) H₂SO₄, and liquid hot water, applied on the BPS resulted in the availability of 52, 48, and 25 cellulose after treatment, respectively. Saccharification of the pretreated BPS with 10FPU/g dry solids (29.3mg protein/g d.s) crude enzyme from Trichoderma harzianum LMLBP07 13-5 at 50°C and a substrate loading of 10 to 15 released 3.8 to 21.8g/L and from T. longibrachiatum LMLSAUL 14-1 released 5.4 to 43.5g/L glucose to the biomass. Ethanol was produced through separate hydrolysis and fermentation (SHF) of alkaline pretreated BPS hydrolysate using Saccharomyces cerevisiae UL01 at 30°C and 100rpm. Highest ethanol produced was 17.6g/L. Banana pseudostem was shown as a potentially cheap substrate for bioethanol production.

Sclerocarya birrea (Morula tree) is one of the indigenous trees bearing wild fruits with various applications in the African communities. Wine is a globally known beverage usually made from grapes; however, recently, other fruits, including wild fruits with a considerable amount of sugars, can be used for making wines. The marula fruit wine is also important in many communities for cultural activities and can be enjoyed by people of varying age groups depending on the age of the product. In recent years, there has been growing interest in shifting from traditional marula winemaking to developing technologies for the marula winemaking process and commercialisation. The process of marula winemaking is similar to the production of grape wines, which entails collection, selection and washing of the fruits; extraction of the juice and mashing; formation and removal of the scum; and ultimately spontaneous fermentation of the resulting juice. The new process in marula winemaking would take into consideration the use of starter cultures as either monoculture or mixed cultures developed from the native marula fruit microbiota and the pasteurisation of the juice. The main challenge or difficulty with marula is the extraction of sugar and other soluble solids from the pulp more than it is for the grapes. The other challenge confronting the sustainability of marula wine is the seasonality of the fruit and poor juice yield. It is therefore imperative to develop strategies to increase the juice yield without affecting the quality, to preserve the marula fruits to ensure the year-round presence of marula fruit wine in the markets and, consequently, to improve the income generation capacity of the households dependent on the product. In addition to achieving a high juice yield, it is imperative to ensure consistent quality wine products. This review gives an overview of the S. birrea subsp. caffra and the biochemical components of the fruits or juice. It also highlights the use of marula fruits for wine production in African communities. The potential economic sustainability of the marula fruit wine is explored, particularly in southern Africa, where the marula tree (Morula) is abundant and the marula fruit wine is popularly produced. The review also examines the opportunities, challenges and future prospects of the marula fruit wine.

Purpose: The microorganisms that possess diverse and improved traits for biotechnological applications provide an opportunity to address some of the current industrial challenges such as the sustainability of fuel energy and food. The aim of this study was to isolate and select the potential yeast isolates from sugarcane bagasse for single oil production. Methods: The oleaginocity of the yeasts was confirmed through a gravimetric analysis of lipids, Nile red, sulfo-phosphovanillin (SPV) and a gas chromatography method for fatty acid methyl esters (FAME). The identification of the selected yeasts was carried out through a 5.8S of the ribosomal internal transcribed spacer (ITS) and 26S ribosomal DNA (rDNA) sequences. The carbohydrate and protein contents were estimated using phenol-sulfuric acid and hot trichloroacetic acid method, respectively. Results: The yeast isolates accumulated lipids of between 28% and 67% of the dry cell weight, and 22–33% based on the SPV assay, qualifying them as oleaginous yeasts. The selected yeasts were identified as Candida ethanolica and Pichia manshuriica. The lipids contained high levels of fatty acids in the following order: oleic acid, palmitic acid, stearic acid, and linoleic acid, which made up 82% of the total lipids. Conclusion: All the six selected yeast strains have the potential to produce single cell oils and other metabolites. The fatty acids composition of the selected yeast species was found to be suitable for the applications in biofuel, nutraceutical, and food industry. The yeast strains require evaluation in lignocellulosic hydrolysate for the production of single cell oils to be cost effective.

The use of food‐based biomass and arable land for bio‐oil and biofuel production could compromise global food security. Therefore, renewable and environmentally friendly oils for biofuels from oleaginous microorganisms such as yeasts and microalgae (heterotrophic and mixotrophic) are gaining interest within the scientific community. These microorganisms have shorter cultivation times and higher lipid productivity when compared to higher plants/food crops/autotrophic microorganisms. Despite many advantages, the high carbon requirements and production cost are limiting factors that hinder their deployment at a commercial scale. Lignocellulosic waste substrates are abundant and inexpensive materials that are rich in organic carbon in the form of cellulose and hemicellulose, which release bioavailable forms of sugars upon hydrolysis. Recent studies have shown the tremendous potential of the hydrolysates of these substrates to be utilized as carbon sources for biomass production and the accumulation of lipids in oleaginous hetero‐/mixotrophic microorganisms. Therefore, this review highlights the potential use of lignocellulosic biomass as a low‐cost carbon substrate for the cultivation of hetero‐/mixotrophic microalgae and yeast for microbial oil production for commercial applications. It also examines the current status, challenges, and future prospects for the utilization of lignocellulose biomass.