Agbaje Lateef

Enzymatic Trends of Fructooligosaccharides Production by Microorganisms

Fructooligosaccharides are influential prebiotics that affect various physiological functions in such a way that they promote positive impact to health. They occur naturally in many fruits and vegetables in trace amounts. However, they are mainly produced commercially by the reaction of microbial enzymes with di- or polysaccharides, such as sucrose or inulin as a substrate. For maximum production of fructooligosaccharides on an industrial level, development of more enzymes with high activity and stability is required. This has attracted the attention of biotechnologists and microbiologists worldwide. This study aims to discuss the new trends in the production of fructooligosaccharide and its effect on numerous health qualities through which it creates great demand in the sugar market.

Biogenic synthesis of silver nanoparticles using a pod extract of Cola nitida: Antibacterial and antioxidant activities and application as a paint additive

Abstract This work reports the biogenic synthesis of silver nanoparticles (AgNPs) using the pod extract of Cola nitida, the evaluation of their antibacterial and antioxidant activities, and their application as an antimicrobial additive in paint. The AgNPs were characterized with UV–Vis spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The AgNP solution was dark brown with a maximum absorbance occurring at 431.5 nm. The FTIR spectrum showed strong peaks at 3336.85, 2073.48, and 1639.49 cm−1, indicating that proteins acted as the capping and stabilization agents in the synthesis of the AgNPs. The AgNPs were spherical, with sizes ranging from 12 to 80 nm. Energy dispersive X-ray (EDX) analysis showed that silver was the prominent metal present, while the selected area electron diffraction pattern conformed to the face-centred cubic phase and crystalline nature of AgNPs. At various concentrations between 50 and 150 μg/ml, the AgNPs showed strong inhibition of the growth of multidrug resistant strains of Klebsiella granulomatis, Pseudomonas aeruginosa, and Escherichia coli. In addition, at 5 μg/ml, the AgNPs completely inhibited the growth of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, A. flavus and A. fumigatus in a paint-AgNP admixture. The AgNPs exhibited a potent antioxidant activity with an IC50 of 43.98 μg/ml against 2,2-diphenyl-1-picrylhydrazyl and a ferric ion reduction of 13.62–49.96% at concentrations of 20–100 μg/ml. This study has demonstrated the biogenic synthesis of AgNPs that have potent antimicrobial and antioxidant activities and potential biomedical and industrial applications. To the best of our knowledge, this work is the first to use the pod extract of C. nitida for the green synthesis of nanoparticles.

Antimicrobial resistance of bacterial strains isolated from orange juice products

Forty samples of twenty brands of sachet orange juice products were examined microbiologically. All the products were contaminated with bacteria and yeasts. The organisms encountered include Saccharomyces cerevisiae, Saccharomyces sp, Rhodotorula sp, Bacillus cereus, Bacillus subtilis, Escherichia coli, Staphylococcus aureus, Streptococcus pyogenes and Micrococcus sp . The resistances of thirty bacterial strains isolated from orange juice products to the commonly used antibiotics were studied. About 66.67% of the isolates were resistant to augmentin and amoxycillin; 63.33% to cotrimoxazole, 56% to cloxacillin, and 23.33% to tetracycline. Resistances of 10, 6.67, and 3.33% were obtained for gentamicin, erythromycin and chloramphenicol respectively. Among the eight antibiotics tested, seven patterns of drug resistance were obtained. Six out of these are multiple-drug resistance with number of antibiotics ranging between 2 to 8. While MIC of amoxycillin ranged between 10-25mg/ml for the strains of E. coli, MIC of 10-20mg/ml was obtained for the strains of S. aureus . The MIC for cloxacillin was 0.1-1.0mg/ml for E. coli strains, and 0.01-1.0mg/ml for S. aureus strains. In all, ten strains of the bacterial isolates had evidence for the production of β-lactamases. Key words: Orange juice, antibiotics, resistance pattern, β-lactamase, microbiological standard. African Journal of Biotechnology Vol.3(6) 2004: 334-338

A novel approach to the green synthesis of metallic nanoparticles: the use of agro-wastes, enzymes, and pigments

Abstract The green synthesis of nanoparticles has received great attention in recent times owing to its advantages such as cost effectiveness, simplicity, eco-friendliness, biocompatibility, and wide applications over the conventional chemical and physical methods. Various kinds of biomolecules from microorganisms and plants have been successfully utilized for the synthesis of metallic and nonmetallic nanoparticles, and these have been well documented. However, the recent increase in the fabrication of metallic nanoparticles using agro-wastes, enzymes and microbial and plant-derived pigments and their respective areas of applications have not been compiled as a review article. Therefore, the present efforts have been aimed at compilation of reports on the use of these novel bio-resources for the green synthesis of nanoparticles. To the best of our knowledge, this is the first review article on the green synthesis of metallic nanoparticles using diverse agro-wastes, enzymes, and pigments of biological origin. It is envisaged that the compendium will bring to the fore the emerging importance of these bio-resources for nanobiotechnological applications.

Biomedical and Catalytic Applications of Gold and Silver-Gold Alloy Nanoparticles Biosynthesized Using Cell-Free Extract of Bacillus Safensis LAU 13: Antifungal, Dye Degradation, Anti-Coagulant and Thrombolytic Activities

This study investigated the green biosynthesis of gold (Au) and silver-gold alloy (Ag-Au) nanoparticles using cell-free extract of Bacillus safensis LAU 13 strain (GenBank accession No: KJ461434). The biosynthesized AuNPs and Ag-AuNPs were characterized using UV-Vis spectroscopy, Fourier-transform infrared spectroscopy, and transmission electron microscopy. Evaluation of the antifungal activities, degradation of malachite green, anti-coagulation of blood, and thrombolysis of human blood clot by the biosynthesized nanoparticles were investigated. The AuNPs and Ag-AuNPs had maximum absorbance at 561 and 545 nm, respectively. The FTIR peaks at 3318, 2378, 2114, 1998, 1636, 1287, 446, 421 cm-1 for AuNPs; and 3310, 2345, 2203, 2033, 1636, 1273, 502, 453, 424 cm-1 for Ag-AuNPs indicated that proteins were the capping and stabilization molecules in the biosynthesized nanoparticles. The particles were fairly spherical in shape with size of 10-45 nm for AuNPs and 13-80 nm for Ag-AuNPs. Moreover, energy dispersive X-ray analysis of AuNPs revealed gold as the most prominent metal in the AuNPs solution, while silver and gold were the most prominent in the case of Ag-AuNPs. Selected area electron diffraction showed the biosynthesized nanoparticles as crystal structures with ring shape pattern. AuNPs and Ag-AuNPs displayed growth inhibitions of 66.67-90.78% against strains of Aspergillus fumigatus and A. niger at concentration of 200 μg/ml, and remarkable degradation (> 90%) of malachite green after 48 h. Furthermore, the nanoparticles prevented coagulation of blood, and also completely dissolved blood clots, indicating the biomedical potential of AuNPs and Ag-AuNPs in the management of blood coagulation disorders. This is the first report of the synthesis of AuNPs and Ag-AuNPs using a strain of B. safensis for biomedical and catalytic applications.

Biogenic synthesis of silver nanoparticles using cell-free extract of Bacillus safensis LAU 13: antimicrobial, free radical scavenging and larvicidal activities

Abstract The cell-free extract of Bacillus safensis LAU 13 strain (GenBank accession No: KJ461434) was used for green biosynthesis of silver nanoparticles (Ag-NPs). Characterization of Ag-NPs was carried out using UV-VIS spectroscopy, Fourier-transform infrared spectroscopy, and transmission electron microscopy. Evaluation of synthesized Ag-NPs as antimicrobial agents was done using multi-drug resistant clinical isolates as well as their synergistic effects when combined with some selected antibiotics. Furthermore, potential of Ag-NPs as antimicrobial additives in paint was demonstrated. The Ag-NPs have maximum absorbance at 419 nm, with peaks at 3308, 2359, 1636, and 422 cm−1, indicating that proteins were the capping and stabilisation molecules in the synthesis of Ag-NPs. The particles were spherical shaped having size of 5-95 nm, with silver as the prominent metal from the energy dispersive X-ray analysis, while selected area electron diffraction pattern agrees well with the crystalline nature and face-centred cubic phase of Ag-NPs. Inhibition of Staphylococcus aureus, Escherichia coli, Klebsiella granulomatis and Pseudomonas aeruginosa was achieved at 100 μg/mL. Improvement of activities of augmentin, ofloxacin and cefixime to the tune of 7.4-142.9% was achieved in synergistic study, while total inhibitions of P. aeruginosa, S. aureus, Aspergillus flavus and Aspergillus fumigatus were achieved in Ag-NPs-paint admixture. The Ag-NPs showed potent antioxidant and larvicidal activities with IC50 and LC50 of 15.99 and 42.19 μg/mL, respectively. The present study demonstrated that the biosynthesized Ag-NPs have potent biological activities, which can find applications in diverse areas. The report adds to the growing biotechnological relevance of B. safensis.

Bacillus safensis LAU 13: a new source of keratinase and its multi-functional biocatalytic applications

A newly isolated bacterium identified as Bacillus safensis based on biochemical tests and 16S rRNA analysis and its mutant variant created by exposure to ultraviolet radiation at 254 nm were investigated for keratinolytic activity. The wild-type strain produced 35.4–50.4 U/mL keratinase over a period of 120 h, while the mutant one yielded 64.4–108.5 U/mL keratinase for the same period of 120 h. The optimal conditions for the enzyme activities were pH 7.5 and 40 °C. The mutant and wild-type strain keratinases retained 59% and 54% of their activity after 12 h pretreatment at 40 °C, and 64% and 60% of their activity after 12 h at pH 7.5, respectively. The keratinases showed high substrate specificity for feathers, but low specificity for human and bovine hairs. The enzymes were activated by Na+, Ca2+, Fe2+ and Mg2+. However, while Mn2+ activated the enzyme from the mutant strain, it inhibited that of the wild type. The mutant and wild-type strain completely degraded whole chicken feathers after 6 and 9 days at 30 ± 2 °C, and also completely dehaired goat skin within 12 and 16 h, respectively, without damage to the skin. Similarly, remarkable destaining of blood-stained cloth occurred within 2–3 h. The obtained results showed an improvement in the properties of the mutant strain for use of the micro-organism or its enzyme as biocatalysts.

Bacteriology and genotoxicity of some pharmaceutical wastewaters in Nigeria

Wastewaters from two pharmaceutical production processes, cotrimoxazole B wastewater (BWW) and Piriton wastewater (PWW), were examined microbiologically and for physico-chemical parameters. Furthermore, the wastewaters were also screened for genotoxicity using Allium cepa assay to assess the risk associated with the discharge of untreated pharmaceutical wastewaters into the environment. The effluents induced various types of chromosomal aberrations, namely, disturbed spindle, vagrant and chromosome bridge, and also showed a dose-dependent reduction in the number of dividing cells. The mitotic inhibition ranged from 38.6 to 67.2%. The mean root length at 20% of BWW and all concentrations except 1% of PWW were significantly different from the control values (p < 0.05). The EC50 of the root growth inhibition was 4.17 and 12.45% for PWW and BWW, respectively. The wastewater physico-chemical analysis revealed that most parameters were within the allowable limits. The wastewaters had similar microbial load index of 107 cfu ml−1, indicating dense populations of bacteria, which may be due to the richness of the wastewaters in nutrients particularly sulphate, nitrate and phosphate. Coliform bacteria concentrations in the PWW and BWW wastewaters were 50MPN/100 ml and 550MPN/100 ml, respectively. The identified bacterial isolates included Staphylococcus aureus, Escherichia coli, Serratia marcescens, Klebsiella sp, Streptococcus pyogenes, Bacillus licheniformis, Yersinia sp, Proteus vulgaris and Bacillus subtilis. The resistance of the bacterial isolates ranged from 10% for gentamicin to 100% for augmentin, amoxycillin, cloxacillin and nalidixic acid. PWW isolates were more resistant. Seven patterns of multiple drug resistance ranging from 5 to 11 antibiotics were obtained amongst the isolates.

Modelling of biohydrogen generation in microbial electrolysis cells (MECs) using a committee of artificial neural networks (ANNs)

The enhancement of hydrogen yield in microbial electrolysis cells (MECs) requires a robust process model that accurately relates the effect of anodic physicochemical input variables to the process output. Artificial neural networks (ANNs) have been used for the modelling of complex and non-linear processes. This paper reports the modelling of biohydrogen yield in MECs by using a committee of five ANNs. A topology of 6–(6, 8, 11, 12, 14)–1 was adopted, corresponding to the number of neurons of inputs, hidden (varied) and output layers. The ANN inputs were substrate type, substrate concentration, pH, temperature, applied voltage and reactor configuration. Model development was carried out with 50 data points from 15 published studies. The coefficients of determination (R2) between the experimental and predicted hydrogen yields for the five models were as follows: 0.90, 0.81, 0.85, 0.70 and 0.80. Model validation on new MEC processes showed a strong correlation between the observed and predicted hydrogen yields. Sensitivity analysis revealed that the performance of MEC was highly affected by variations in the substrate type, followed by applied voltage, substrate concentration, pH, MEC configuration and temperature in decreasing order. This study showed that the committee model accurately modelled the non-linear relationship between the considered physicochemical parameters of MEC and hydrogen yield, and thus could be used to navigate the optimization window in MEC scale-up processes.

The biology and potential biotechnological applications of Bacillus safensis

Abstract Bacillus safensis colonizes a wide range of habitats, many of which are stringent for the survival of some microorganisms. Its survival in extreme environments relies on its unique physiological and genotypic characteristics. It was originally identified as a recalcitrant contaminant in a spacecraft-assembly facility (SAF) at the Jet Propulsion Laboratory, USA, from which it derived its specific epithet, safensis. The bacterium belongs to the Bacillus pumilus group, and is closely related to Bacillus pumilus, Bacillus altitudinis, Bacillus xiamenensis and Bacillus invictae. At times, B. safensis has been erroneously identified as B. pumilus, especially when extensive molecular analyses and some mass spectroscopic methods, such as matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), are not considered. B. safensis possesses some plant growth-promoting traits and also has promising biotechnological applications due to its ability to produce various industrial enzymes and industrially applicable secondary metabolites. It may be regarded as a safe industrial microorganism because its pathogenicity has never been evidenced. This review attempts to chronicles the biology of B. safensis and its exploit as a potential industrially important bacterium. The ecology, physiology, genetics, and biotechnological applications of B. safensis are hereby presented in this review. This represents the first compendium of information on its attributes and applications that may be useful in opening a new vista of research on the bacterium.