Functional foods are essential food products that possess health-promoting properties for the treatment of infectious diseases. In addition, they provide energy and nutrients, which are required for growth and survival. They occur as prebiotics or dietary supplements, including oligosaccharides, processed foods, and herbal products. However, oligosaccharides are more efficiently recognized and utilized, as they play a fundamental role as functional ingredients with great potential to improve health in comparison to other dietary supplements. They are low molecular weight carbohydrates with a low degree of polymerization. They occur as fructooligosaccharide (FOS), inulooligosaccharadie (IOS), and xylooligosaccahride (XOS), depending on their monosaccharide units. Oligosaccharides are produced by acid or chemical hydrolysis. However, this technique is liable to several drawbacks, including inulin precipitation, high processing temperature, low yields, and high production costs. As a consequence, the application of microbial enzymes for oligosaccharide production is recognized as a promising strategy. Microbial enzymatic production of FOS and IOS occurs by submerged or solid-state fermentation in the presence of suitable substrates (sucrose, inulin) and catalyzed by fructosyltransferases and inulinases. Incorporation of FOS and IOS enriches the rheological and physiological characteristics of foods. They are used as low cariogenic sugar substitutes, suitable for diabetics, and as prebiotics, probiotics and nutraceutical compounds. In addition, these oligosaccharides are employed as anticancer, antioxidant agents and aid in mineral absorption, lipid metabolism, immune regulation etc. This review, therefore, focuses on the occurrence, physico-chemical characteristics, and microbial enzymatic synthesis of FOS and IOS from coprophilous fungi. In addition, the potential health benefits of these oligosaccharides were discussed in detail.

The emergence of COVID-19 continues to pose severe threats to global public health. The pandemic has infected over 171 million people and claimed more than 3.5 million lives to date. We investigated the binding potential of antiviral cyanobacterial proteins including cyanovirin-N, scytovirin and phycocyanin with fundamental proteins involved in attachment and replication of SARS-CoV-2. Cyanovirin-N displayed the highest binding energy scores (−16.8 ± 0.02 kcal/mol, −12.3 ± 0.03 kcal/mol and −13.4 ± 0.02 kcal/mol, respectively) with the spike protein, the main protease (Mpro) and the papainlike protease (PLpro) of SARS-CoV-2. Cyanovirin-N was observed to interact with the crucial residues involved in the attachment of the human ACE2 receptor. Analysis of the binding affinities calculated employing the molecular mechanics-Poisson–Boltzmann surface area (MM-PBSA) approach revealed that all forms of energy, except the polar solvation energy, favourably contributed to the interactions of cyanovirin-N with the viral proteins. With particular emphasis on cyanovirin-N, the current work presents evidence for the potential inhibition of SARS-CoV-2 by cyanobacterial proteins, and offers the opportunity for in vitro and in vivo experiments to deploy the cyanobacterial proteins as valuable therapeutics against COVID-19.

Huge amounts of wastewater are generated during food process, and usually contain high nutrient concentration. The present study investigated the feasibility of dairy and poultry wastewaters as growth media for Chlorella sp. T4 cultivation for concomitant nutrient removal and biomass propagation for biofuel production. Microalgae Chlorella sp. T4 was cultivated in poultry and dairy wastewater collected at different stage of wastewater treatment to study the growth, physiological respond, nutrient removal efficiency and biochemical composition. The strains showed phycoremediation potential resulting to high nitrogen and phosphorus removal efficiency in dairy and poultry wastewater ranging from 85–95% and 35–93%, respectively. High biomass yield of 1.28 ± 0.1 g L−1 was obtained in poultry wastewater compared to 0.85 ± 0.02 g L−1 obtained in dairy wastewater. The biomass contained significant amounts of lipids (16.2–25.7 % Dry wt.), carbohydrates (20.7–33.1 % Dry wt.), and proteins (24.5–34.6 % Dry wt.), regardless of the wastewater type. The fatty acid analysis revealed that palmitic (16:0), oleic (18:1), and linoleic (18:2) acids were the major fatty acids accumulated by Chlorella sp. T4 when cultivated in poultry and dairy wastewater. Biodiesel properties of lipids extracted from the cell grown in poultry and dairy wastewater complied with most of the international standards by ASTM D6751 and EN 14214. The results of this study revealed that Chlorella sp. T4 is a potential candidate for dairy and poultry wastewater treatment, with a significant accumulation of lipid, protein and carbohydrates for use in biofuel production.

There is a great interest in prebiotics consumptions eminence by their health promoting properties and economic market value. Filamentous fungi have been implicated as the key producers of fructosyltransferase (Ftase) and inulinase for synthesis of fructooligosaccharides (FOSs), which is used as a bioactive ingredient in functional foods. In this study, sixty-one indigenous coprophilous fungal strains were isolated, purified to monoculture and investigated for their potential use in biotransformation of sucrose and inulin into fructooligosaccharides (FOSs) and inulooligosaccharides (IOSs) by producing Ftase and inulinase enzymes, respectively. The molecular identification by 18S rDNA sequencing and morpho-taxonomic keys revealed that axenic fungal strains belonged to the genera Aspergillus, Neocosmospora, Trichoderma, Mucor and Fusarium. The crude enzyme extract from the isolates showed hydrolysis zones of 15-30 mm on the 2,3,5-triphenyltetrazolium chloride (TTC) and Lugol's iodine solution assay plates confirming the Ftase and inulinase activities, respectively. The submerged culture filtrates of eight fungal isolates showed high Ftase activity while six different fungal isolates exhibited high inulinase activity. The reaction products analysed with thin-layer chromatography and high-performance liquid chromatography coupled with refractive index detection indicated the presence of FOSs and IOSs. The strains isolated in this study have potential biotechnological implications to produce FOSs and IOSs.

Fructooligosaccharides (FOS) produced via sucrose biotransformation by partially purified Fructosyltransferase (Ftase) from an indigenous coprophilous Aspergillus niger strain XOBP48 (AnXOBP48) are reported to have antioxidant and nutraceutical properties in the present study. The Ftase activity on sucrose yielded FOS identified as monomeric glucose, 1- kestose (GF2), and 1,1– kestotetraose (GF3) which were further purified and quantified using HPLC-RI system. The antioxidant activities of purified FOS at concentrations of 1, 1.5, 3, 6, 12, 24 and 48 μg/ml were determined by applying three experimental models and comparing their properties with FOS standards and vitamin C. The free radical scavenging activity measured by 1,1 - diphenyl-2-picryl hydroxyl (DPPH) assay, ferric reducing antioxidant power (FRAP) assay and nitric oxide (NO) radical inhibition assay, yielded IC50 values of 2.6 μg/ml, 3.9 μg/ml and 3.4 μg/ml, 3.8 μg/ml and 0.69 μg/ml, 0.74 for purified GF2 and GF3, respectively. The free radical scavenging and inhibition activities showed a concentration dependent antioxidant activity of purified FOS with no significant differences as compared to the standards p < 0.01 and vitamin C. In conclusion, the results demonstrated that purified FOS could be exploited in biotechnological applications and/or as to be used as functional ingredients in commercial products such as the production of nutraceutical compounds due to their potential antioxidant properties.

Contamination of freshwater raceway ponds impedes the commercial cultivation of microalgae. Acclimatization of freshwater microalgae to hypersaline conditions offers a means to reduce contamination. A freshwater Chlorella species was cultured in a gradient of salinities ranging from 5 to 40 parts per thousand and pulse amplitude modulated fluorometry recorded photosynthetic functioning. While the average salinity of seawater is 35 parts per thousand, optimum acclimatization occurred at 20 parts per thousand, at which point the growth rate (1.6 mu g chl a L(-1)d(-1)) was not significantly different from the control (1.8 mu g chl a L(-1)d(-1)). The maximum relative electron transfer rate was lower (9 to 12 mu mol m(-2)s(-1)) at 5 to 20 parts per thousand as compared to 40 parts per thousand (28 mu mol m(-2)s(-1)) where no algal growth was recorded. ATP and NADPH were thus shunted towards synthesis of molecules that offset cytoplasmic osmotic stress. Culturing this Chlorella strain in raceway ponds under saline conditions may reduce contamination and improve productivity.

A novel severe acute respiratory syndrome coronavirus (SARS-CoV-2) has emerged as the causative agent behind the coronavirus disease 2019 (COVID-19) pandemic. Treatment efforts have been severely impeded due to the lack of specific effective antiviral drugs for the treatment of COVID-associated pathologies. In the present research endeavour the inhibitory prospects of cyanobacterial metabolites were assessed at the active binding pockets of the two vital SARS-CoV-2 proteases namely, main protease (M-pro) and the papain-like protease (PLpro) that proteolytically process viral polyproteins and facilitate viral replication, employing anin silicomolecular interaction-based approach. It was evident from our analysis based on the binding energy scores that the metabolites cylindrospermopsin, deoxycylindrospermopsin, carrageenan, cryptophycin 52, eucapsitrione, tjipanazole, tolyporphin and apratoxin A exhibited promising inhibitory potential against the SARS-CoV-2 M-pro. The compounds cryptophycin 1, cryptophycin 52 and deoxycylindrospermopsin were observed to display encouraging binding energy scores with the PL(pro)of SARS-CoV-2. Subsequent estimation of physicochemical properties and potential toxicity of the metabolites followed by robust molecular dynamics simulations and analysis of MM-PBSA energy scoring function established deoxycylindrospermopsin as the most promising inhibitory candidate against both SARS-CoV-2 proteases. Present research findings bestow ample scopes to further exploit the potential of deoxycylindrospermopsin as a successful inhibitor of SARS-CoV-2in vitroandin vivoand pave the foundation for the development of novel effective therapeutics against COVID-19. Communicated by Ramaswamy H. Sarma

An extracellular fructosyltransferase (Ftase) enzyme with a molar mass of ≈70 kDa from a newly isolated indigenous coprophilous fungus Aspergillus niger sp. XOBP48 is purified to homogeneity and characterized in this study. The enzyme was purified to 4.66-fold with a total yield of 15.53% and specific activity of 1219.17 U mg−1 of protein after a three-step procedure involving (NH4)2SO4 fractionation, dialysis and anion exchange chromatography. Ftase showed optimum activity at pH 6.0 and temperature 50 °C. Ftase exhibited over 80% residual activity at pH range of 4.0–10.0 and ≈90% residual activity at temperature range of 40–60 °C for 6 h. Metal ion inhibitors Hg2+ and Ag+ significantly inhibited Ftase activity at 1 mmol concentration. Ftase showed Km, vmax and kcat values of 79.51 mmol, 45.04 µmol min−1 and 31.5 min−1, respectively, with a catalytic efficiency (kcat/Km) of 396 µmol−1 min−1 for the substrate sucrose. HPLC-RI experiments identified the end products of fructosyltransferase activity as monomeric glucose, 1-kestose (GF2), and 1,1-kestotetraose (GF3). This study evaluates the feasibility of using this purified extracellular Ftase for the enzymatic synthesis of biofunctional fructooligosaccharides.

This study investigated the interrelations between hydrogen synthesis and Photosystem I electron transport rate in Chlamydomonas reinhardtii. The fluorescence of both photosystems (PS I and PS II) was monitored using a Dual Pulse Amplitude Modulated (PAM) Fluorometer. Hydrogen synthesis was induced by eliminating sulphur from the growth media (TAP-S). Multiple physiological parameters [rETR, Y (I), Y (II), NPQ, a, FVF, and YL"YII] were recorded using the Dual PAM and correlated to hydrogen produced. There was a 66% increase in Photosystem I rETR,a during hydrogen production. A significant direct correlation existed between PS 1 rETR,a and hydrogen evolution values over the ten-day period (r = 0.895, p < 0.01) indicating that PS I can be considered as a driver of H2 production. Significant correlations between rETR,a of PS I and H2 evolution suggest a novel physiological indicator to monitor H2 production during the three critical phases identified in this study.

Microalgae are promising feedstock to produce biodiesel and other value added products. However, the water footprint for producing microalgal biodiesel is enormous and would put a strain on the water resources of water stressed countries like South Africa if freshwater is used without recycling. This study evaluates the utilization of pre-chlorinated wastewater as a cheap growth media for microalgal biomass propagation with the aim of producing biodiesel whilst simultaneously remediating the wastewater. Wastewater was collected from two wastewater treatment plants (WWTPs) in Durban, inoculated with Neochloris aquatica and Asterarcys quadricellulare and the growth kinetics monitored for a period of 8 days. The physicochemical parameters; including chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) were determined before microalgal cultivation and after harvesting. Total lipids were quantified gravimetrically after extraction by hexane/isopropanol (3:2 v/v). Biodiesel was produced by transesterification and characterised by gas chromatography. The total carbohydrate was extracted by acid hydrolysis and quantified by spectrophotometric method based on aldehyde functional group derivatization. Asterarcys quadricellulare utilized the wastewater for growth and reduced the COD of the wastewater effluent from the Umbilo WWTP by 12.4%. Total nitrogen (TN) and phosphorus (TP) were reduced by 48% and 50% respectively by Asterarcys quadricellulare cultivated in sterile wastewater while, Neochloris reduced the TP by 37% and TN by 29%. Although the highest biomass yield (460 mg dry weight) was obtained for Asterarcys, the highest amount of lipid (14.85 ± 1.63 mg L−1) and carbohydrate (14.84 ± 0.1 mg L−1) content were recorded in Neochloris aquatica. The dominant fatty acids in the microalgae were palmitic acid (C16:0), stearic acid (C18:0) and oleic acid (C18:1). The biodiesel produced was determined to be of good quality with high oxidation stability and low viscosity, and conformed to the American society for testing and materials (ASTM) guidelines.

Microalgae are diverse microorganisms inhabiting a wide range of habitats with only a small fraction being cultivated for human use. Recently, interest in microalgal research has increased in the quest for alternative renewable fuels due to possible depletion of fossil fuels in the near future. However, costly downstream processing has hampered the commercialization of biofuels derived from microalgae. Several value added products of industrial, pharmaceutical and agricultural relevance could be simultaneously derived from microalgae during bioenergy production. Despite these value-added products having the potential to offset the high cost of downstream processing of renewable fuels, their production has not been explored in-depth. This review presents a critical overview of the current state of biotechnological applications of microalgae for human benefit and highlights possible areas for further research and development.

Diverse African traditional fermented foods and beverages, produced using different types of fermentation, have been used since antiquity because of their numerous nutritional values. Lactic acid bacteria (LAB) isolated from these products have emerged as a welcome source of antimicrobials and therapeutics, and are accepted as probiotics. Probiotics are defined as live microbial food supplements which beneficially affect the host by improving the intestinal microbial balance. Currently, popular probiotics are derived from fermented milk products. However, with the growing number of consumers with lactose intolerance that are affected by dietary cholesterol from milk products, there is a growing global interest in probiotics from other food sources. The focus of this review is to provide an overview of recent developments on the applications of probiotic LAB globally, and to specifically highlight the suitability of African fermented foods and beverages as a viable source of novel probiotics.

Biodiesel, a renewable fuel has a great potential in fulfilling an ever-increasing transport fuel demand. The enzymatic conversion process of feedstock oil to biodiesel is greener when compared to the conventional approach of chemical conversion due to mild reaction conditions and less wastewater generation. Lipases obtained from various microbial sources have been widely applied as catalysts for the conversion of oil to biodiesel. Biodiesel and glycerol obtained by enzymatic conversion have shown a higher purity as compared to that obtained by other conversion techniques. Enzymatic conversion of oil to biodiesel is less energy intensive because of milder reaction conditions and fewer purification steps involved in processing. Lipases, due to their catalytic efficiency and specificity, have emerged as a great tool for converting a wide range of feedstock oils to biodiesel. This manuscript presents an overview of the use of enzymatic conversion for making biodiesel production sustainable and environmentally-friendly. The constraints of enzymatic conversion are the high cost of the enzyme and its inhibition by alcohol and glycerol. The possible solutions to overcome these constraints are discussed. Recent advances to develop an effective process for enzymatic conversion of feedstock oils into biodiesel are critically evaluated. Prospective and challenges in scaling up of this technology are also discussed.

The production of fructooligosaccharides (FOS) and inulooligosaccharides (IOS) of varying degrees of polymerization (DP) was optimized by orthogonal experimental designs using central composite design (CCD) and response surface methodology (RSM). The FOS produced were quantified and maximal GF2, GF3 and GF4 were 211.09mM, 156.06mM and 43.99mM respectively at pH 5.6 and 60 degrees C. Maximal IOS produced were quantified and F3, F4 and F5 were 70.3mM, 38.8mM and 12.43mM respectively at pH 6.0 and 60 degrees C. The detection and quantification of oligosaccharides of specific chain length from inulin hydrolysis and sucrose elongation were carried out using high performance liquid chromatography with refractive index (HPLC-RI) detection, thin layer chromatography (TLC) and mass spectrometry with electrospray ionization (MS-ESI). FOS and IOS were ionized and detected in the positive ion mode using 1mM LiCl, [M+Li](+). The FOS produced by the action of fructosyltransferases were monosaccharides (m/z=187.98), disaccharides (m/z=349.19), 1-kestose (GF2; m/z=511.25), nystose (GF3; m/z=673.27) and fructofuranosyl nystose (GF4; m/z=835.45). IOS produced were identified as fructose (F; m/z=187.01), inulobiose (F2; m/z=349.22) inulotrioses (F3; m/z=511.23), inulotetraoses (F4; m/z=673.29) and inulopentaoses (F5; m/z=835.22).

South Africa has a rich microalgal biodiversity which has the potential to be used for renewable bio-fuel production in the region. Bioprospecting for oleaginous microalgae in KwaZulu Natal Province, South Africa, resulted in the establishment of a microalgal culture collection system for alternative energy research in the country. A potential hyper-lipid-producing Chlorella spp. strain was isolated, purified, and cultured in supplemented post-chlorinated wastewater for biomass and lipid production at the laboratory scale under batch mode. The microalgal strain was cultivated in different strengths of BG-11 media supplemented with wastewater from a local municipal domestic wastewater treatment plant. The Chlorella spp. was grown using ambient dissolved carbon dioxide in shake flasks under photosynthetically active radiation (±120 μmolm−2s−1). Microalgal biomass and lipid productivity were monitored at 24-h intervals in the batch mode. The microalgal biomass was analyzed by direct light microscopy and indirectly by spectrophotometry at 600 nm, and the lipids were extracted and quantified. The growth rate of the Chlorella spp. was enhanced in post-chlorinated wastewater supplemented with 5 mM NaNO3 with maximal biomass productivity. A dramatic increase in lipid yield was achieved with the post-chlorinated wastewater supplemented with 25 mM NaNO3. Low dosages of free chlorine were found to enhance microalgal growth. These findings serve as a basis for further scale-up trials using municipal wastewater as a medium for microalgal biomass and lipid production.

High energy prices, rising energy imports, concerns about petroleum supplies and greater recognition of the environmental consequences of fossil fuels have driven interest in renewable transportation biofuels. To assuage the depleting fossil reserves, environmental concerns and the rising cost of fuels in the world market, there is a spurring demand to look for sustainable, greener fuels that are economically competitive with substantial environmental benefits. At this juncture, the positive attributes of biodiesel makes it a viable alternative to the conventional, petrodiesel. As the emphasis switched to production of natural oils for biodiesel, microalgae became the exclusive focus of the research. There is a need to develop and deploy microalgae technology as it provides an exciting option for the recycling of fossil fuel emissions. Algal biodiesel opens up a promising avenue for producing several “quads” of biodiesel because microalgae generally produce more of the right kind of high density natural oils needed for the production of biodiesel. Though, a nascent field today, microalgae seem to present the only bio-solution to replace fossil fuels completely. This paper reviews the production processes of biodiesel from microalgae, procedures involved in the microalgal propagation, harvesting and extraction of oil, microalgal strain improvement and importance of manipulation of microalgal lipid composition via metabolic engineering. _____________________________________________________________________________________________________________