Bioprospecting of microbial strains for biofuel production: metabolic engineering, applications, and challenges

The issues of global warming, coupled with fossil fuel depletion, have undoubtedly led to renewed interest in other sources of commercial fuels. The search for renewable fuels has motivated research into the biological degradation of lignocellulosic biomass feedstock to produce biofuels such as bioethanol, biodiesel, and biohydrogen. The model strain for biofuel production needs the capability to utilize a high amount of substrate, transportation of sugar through fast and deregulated pathways, ability to tolerate inhibitory compounds and end products, and increased metabolic fluxes to produce an improved fermentation product. Engineering microbes might be a great approach to produce biofuel from lignocellulosic biomass by exploiting metabolic pathways economically. Metabolic engineering is an advanced technology for the construction of highly effective microbial cell factories and a key component for the next-generation bioeconomy. It has been extensively used to redirect the biosynthetic pathway to produce desired products in several native or engineered hosts. A wide range of novel compounds has been manufactured through engineering metabolic pathways or endogenous metabolism optimizations by metabolic engineers. This review is focused on the potential utilization of engineered strains to produce biofuel and gives prospects for improvement in metabolic engineering for new strain development using advanced technologies.Instituto de BiotecnologíaFil: Adegboye, Mobolaji Felicia. North-West University. Faculty of Natural and Agricultural Sciences. Food Security and Safety Niche Area; SudáfricaFil: Ojuederie, Omena Bernard. North-West University. Faculty of Natural and Agricultural Sciences. Food Security and Safety Niche Area; SudáfricaFil: Ojuederie, Omena Bernard. Kings University. Faculty of Science. Department of Biological Sciences; NigeriaFil: Talia, Paola Mónica. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Agrobiotecnología y Biología Molecular (IABIMO); ArgentinaFil: Talia, Paola Mónica. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Babalola, Olubukola Oluranti. North-West University. Faculty of Natural and Agricultural Sciences. Food Security and Safety Niche Area; Sudáfric

Partial Purification, Characterization and Application of Bacteriocin from Bacteria Isolated Parkia biglobosa Seeds

Staff PublicationBacteriocins are proteinaceous toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strains. Fermented Parkia biglobosa seeds (African locust bean) were screened for bacteriocin-producing lactic acid bacteria (LAB) with the characterization of putative bacteriocins. Bacteriocin-producing lactic acid bacteria (LAB) were identified by 16s rDNA sequencing. Molecular sizes of the bacteriocins were determined using the tricine-sodium dodecyl sulphate-polyacrylamide gel electrophoresis (tricine-SDS–PAGE) and effects of enzymes, pH, detergents and temperature on bacteriocin activity investigated, using standard procedures. Bacteriocins production and activities were measured by spectrophotometric analysis. Statistical analysis was carried out using student t-test and Analyses of Variance. Bacteriocigenic LAB isolated were Lactobacillus plantarum Z1116, Enterococcus faecium AU02 and Leuconostoc lactis PKT0003. They inhibited the growth of both Gram-positive and Gram-negative bacteria. The sizes of bacteriocins Z1116, AU02 and PKT0003 were 3.2 kDa, 10 kDa and 10 kDa, respectively. The synergistic effects of characterized bacteriocins and rifampicin tested on organisms showed significant differences (P < 0.05), as compared with the effects of only one of the two. The antimicrobial activity of the three bacteriocins was deactivated after treatment of the cell-free supernatants with proteinase K, papain, pepsin and trypsin. Parkia biglobosa seeds are, therefore, rich in LAB bacteriocins which could be explored. The biosynthetic mechanisms of LAB bacteriocins could be employed in food safety and security, preservation, peptide design, infection control and pharmacotherapy. This should help in the control of undesirable bacteria and in designing more potent and selective antimicrobial peptides

Preliminary Phytochemical Screening and Antibacterial Properties of Crude Stem Bark Extracts and Fractions of Parkia biglobosa (Jacq.)

A methanolic crude extract of Parkia biglobosa was prepared and later partitioned in succession with different solvents of increasing polarity ranging from n-hexane, chloroform and ethyl acetate to butanol. Phytochemical screening of the extract revealed the presence of alkaloids, tannins, saponins, flavonoids, steroids, glycoside and sugars. The inhibition zones exhibited by the extract against the tested bacteria ranged between 14 ± 0.00 mm (against Escherichia coli) and 28 ± 0.71 mm (against Pseudomonas aeruginosa). The MIC of the methanolic extract of P. biglobosa against isolates ranged between 0.63 mg/mL and 5 mg/mL, while the MIC values exhibited by the n-hexane and aqueous fractions ranged between 0.63 mg/mL and 10 mg/mL. Overall the extract and fractions of P. biglobosa used in this work were found to possess antimicrobial properties which compared favourably with those of streptomycin. These observations make this plant a potential source of bioactive compounds that can be used in management of bacterial infections. The use of this plant as herbal medicaments in African countries and the reports on the toxicity of the plant further show that the plant is non-toxic to humans