Open Access Minireview Article

Next-Generation Sequence: A Review on Metagenomic Approach to Discovery of Novel Enzymes from the Soil Environment

Rita-Cindy Aye-Ayire Sedjoah

Asian Journal of Biotechnology and Bioresource Technology, Page 10-19
DOI: 10.9734/ajb2t/2021/v7i130091

Next-generation sequencing (NGS) makes a large mass of sequences. As a technology that allows the sequence of deoxyribonucleic acid (DNA) molecules larger than one million base pairs, it has been applied in the food research and medical fields. In the food sector, NGS has been used in food safety for the detection of species authenticity of food products and for mostly discovering novel industrial enzymes. The soil ecosystem houses a great number of non-culturable microbes thus novels enzymes can still be discovered to date. The conventional methods used in enzyme discovery have less chances to identify novel gene clusters and bioactivities.  Therefore, there is a dire need for high-throughput technology, together with advanced bioinformatics for the search of novel enzymes or biocatalysts from soil metagenomes. This review article thus gives a summary of the progress in the application of next-generation sequencing in the identification and characterization of novel enzymes with a special focus on enzymes from the soil environment.

Open Access Original Research Article

A Study on Surface Physicochemical Properties of Woods Treated in Emulsion of Waterborne Varnish with Sesame and Grape Seed Oil

Halil Turgut Sahin, Ismail Erbil

Asian Journal of Biotechnology and Bioresource Technology, Page 1-9
DOI: 10.9734/ajb2t/2021/v7i130090

Aims: An eco-friendly coating emulsion prepared with mixture of oils of sesame and grape seed and alkyd-based waterborne varnish. The prepared emulsion applied four different wood substrates (walnut, beech, cedar and fir) in order to be investigated for some selected surface properties.

Study Design: Several test methods were used to evaluate surface physicochemical properties of the coatings. The results obtained may be suggested for the selection of the best varnish-emulsion formulation for the improvement wood substrates and could provide useful evaluation of the test methods employed.

Methodology: The wood species of Beech (Fagus sylvatica), Walnut (Juglans regia), Cedar (Cedrus libani) and Fir (Abies nordmandiana) were selected for the investigation. Commercially available alkyd based waterborne varnish was supplied ready to use form.

Both sesame oil (Sesamum indicum L.) and grape seed oil (Vitis vinifera L.) were obtained from a company that produces them by the cold press technique commercially. Both oils were used as supplied, without additional processing. These oils were added to varnish at 10% and 20% proportions (volume/volume). The 5 μl of distilled water (surface tension of 72.6 mN /m) was applied on wood surface by a sessile droplet method to measure surface contact angles. The surface hardness and scratch resistance of the cured varnish layers on wood substrates were measured with using pencil hardness test procedure according to ASTM-D-3363 standard. Cross cut test also conducted according to EN ISO 2409 standard.

Experimental Findings: It was found that coated walnut samples show 9.8 to 13.5° higher contact angle values in all directions while other three wood samples only show marginally different values (0.1 to 4.3°). The highest contact value of 35.9° and 35.8° was found with samples of Wg20 and Wg10 which treated 20- and 10% grape seed oil proportions in varnish emulsion. The oils of sesame and grape seed typically contain various proportions of fatty acids fractions which are constituents of a carboxylic acid with a long, aliphatic tail. These groups could be created a strong bond in combination with alkyd resin on wood surface. However, the surface energy distribution show only marginally changes regardless of treatment levels and conditions. Therefore, there is not any clear advantage observed on surface wood surface energy levels with coating applications. For 10% grape seed oil/varnish emulsion conditions, the hardness of coated surfaces found to be 3H, 3H, 2H, 2H for walnut, beech, fir and cedar, respectively. At 20% grape seed oil/varnish coatings, all coating surfaces show H level range. For cross hatch experiments, marginally similar trend was observed with 10-and 20% grape seed oil/varnish and 10% sesame oil/varnish emulsion coated wood species. Moreover, it was ranked 2 for fir, ranked 3 for beech and ranked 4 for cedar wood at 20% sesame oil/varnish emulsion coatings. It is noticeable that a correlation was observed between cross cut and surface scratch resistance properties with coated surfaces.

Open Access Original Research Article

Comparative Preservative Potential of Essential Oils of Ocimum gratissimum from Bambili of the North West and Mbonge of the South West Regions of Cameroon on Scomber scombrus

Ngwasiri Pride Ndasi, Tsi Celestine Angu, Wilson Agwanande Ambindei, Nantia Akono Edouard, Diane Youmbi Yimta, Eke Pierre, Agatha Tanya Nguti Kien, Tsouh Fokou Patrick Valere

Asian Journal of Biotechnology and Bioresource Technology, Page 20-29
DOI: 10.9734/ajb2t/2021/v7i130092

Essential oils serve as a natural alternative to chemical or synthetic antimicrobials and antioxidants to fight against food borne pathogens or spoilage organisms, inhibiting lipid peroxidation and extending the shelf life of fish and other seafood. This study examines the antibacterial properties of essential oils from leaves of Ocimum gratissimum L. from two localities of the North West and South West of Cameroon on some pathogenic spoilage gram negative and positive bacteria isolated from mackerel, and their antimicrobial and antioxidant effectiveness on the fish quality during preservation for one month at -18oC. The plant materials were harvested from Bambili, the North West Region of Cameroon and from Mbonge, the South West Region of Cameroon and the essential oils extracted by hydro-distillation using Clevenger-type apparatus. Escherichia coli, Salmonella typhi and Staphylococcus aereus were isolated from mackerel by culture techniques and their susceptibility to the essential oils determined by well diffusion method. Psychrophilic bacteria and Enterobacteraceae counts were used to evaluate the microbiological quality of the fish during storage. Total volatile basic nitrogen and thiobarbituric acid reactive substance assays were used as indices to assess the biochemical quality of the fish during storage. Antibacterial susceptibility test showed that essential oils of O. gratissimum from the North West and South West Regions were active on all the tested microorganisms with different degree.The inhibitory diameters for essential oil from the South West Region were 28.0 mm, 27.2 mm and 26.0 mm while that for essential oil from the Bambili were 24.1 mm, 20.4mm and 21.9 mm for Staphylococcus aereus, Escherichia coli and Salmonella typhi respectively. At the end of storage periods, the values of Psychrotrophs plate counts, total volatile base nitrogen and thiobarbituric acid reactive substances for fish samples treated with essential oil from the Mbonge were 2.71log10cfu/g, 12.88 mgN/100g and 0.88 mgMDA/Kg, while that treated with North West essential oil were 3.00 log10cfu/g, 16.24 mgN/100g and 1.26 mgMDA/Kg respectively. From the obtained results, essential oil of O. gratissimum from the Mbonge was the most effective in preserving Atlantic mackerel.

Open Access Original Research Article

Isolation and Molecular Characterization of Two Bacterial Strains with Higher Bioleaching Potentials, from Agbaja Mines (Kogi State, Nigeria)

Ekpa Emmanuel, Abdulrahman Abdullateef, Jamila Saleh, Muhibat Komolafe Bolanle

Asian Journal of Biotechnology and Bioresource Technology, Page 47-63
DOI: 10.9734/ajb2t/2021/v7i130094

Bacterial strains with higher bioleaching capacity (BC) are relevant for the mining industry, being more eco-friendly methods, for instance more than cyanide based extraction.  Microbiological samples were collected from selected sites in Agbaja Mines, which after a growth enrichment step, cultures were screened for iron BC, including chemical quantification of iron species. Strains with the highest BC were morphologically, biochemically and molecularly characterized. Two bacterial strains with iron BC Leptospirillum sp. And Acidithiobacillus sp. (AGBAJA-1 and AGBAJA-2, respectively) were isolated from Agbaja Mines of Kogi State Nigeria.  Bioleaching studies carried out shows that prior to inoculation of the iron ore solution with the organisms, raw Agbaja iron ore had a concentration of 25.10 mg/g iron while Zinc, Copper and Lead were 1.3903 mg/g, 0.094 mg/g, and 0.2813 mg/g respectively from X-ray diffraction analysis. The degree of bioleaching as a function of the amount of iron leached into solution was higher (in four weeks bioleaching test) than the other metals. Molecular characterization by sequencing  the 16S ribosomal unit, amplification with universal primers, yielded high quality amplicons that were sequenced.  Their phylogenetic/Blast comparison showed more than 97% relationships with Acidithiobacillus ferroxidans ATCC 23270 and Leptospirillum ferrovirans DSM 15468, families of bacteria in the National Centre for Biotechnology Information (NCBI) data bank. These are moderately thermophilic acidophilic bacteria that may represent an opportunity for developing a greener iron extraction process.

Open Access Review Article

Role of Microbial Biomechanics in Composting with Special Reference to Lignocellulose Biomass Digestion

Philip Ghanney, Joseph Xorse Kugbe, Dominic Kwadwo Anning

Asian Journal of Biotechnology and Bioresource Technology, Page 30-46
DOI: 10.9734/ajb2t/2021/v7i130093

Biomass transformation of lignocellulose into compost offers ‘green’ technology for sustainable agricultural development. So far, biomass conversion into compost outweighs fossil resources and other conversational techniques due to the low production cost and environmental pollution reduction. Although composting has aesthetically been resorted to in the digestibility of lignocellulose biomass, its realization has keenly been directed towards adding chemical reagents. However, inclining massively to this treatment instigated research bias as microorganisms’ biomass digestibility remains mostly inadequate. Besides, proliferated growth and activities of microorganisms native to lignocellulose biomass are usually disrupted by chemical treatment. The microbial flora (fungi, bacteria, actinomycetes, archaea, and yeast) involved in composting synthesizes complex biocatalysts (enzymes) that are crucial for solubilizing the biopolymers of lignocellulose materials at a density of 1012 cells g-1. Filamentous fungi are by far excellent degraders of lignocellulose in nature. To adequately ensure sustainable lignocellulose digestibility, microbial engineers must subject research studies to surpassing conditions (feedstock formulation and management processes) suitable for inducing ligninolytic, cellulolytic, and hemicellulolytic enzymes. Hence, the state-of-the-art-method of this review provides insights that relate to mechanisms of microbial reactions on the digestibility of lignocellulose biomass during composting.