Bacterial Cellulose Production from agricultural Residues by two Komagataeibacter sp. Strains.

Agricultural residues are constantly increasing with increased farming processes, and improper disposal is detrimental to the environment. Majority of these waste residues are rich in lignocellulose, which makes them suitable substrate for bacterial fermentation in the production of value-added products. In this study, bacterial cellulose (BC), a purer and better form of cellulose, was produced by two Komagataeibacter sp. isolated from rotten banana and kombucha drink using corncob (CC) and sugarcane bagasse (SCB) enzymatic hydrolyzate, under different fermentation conditions, that is, static, continuous, and intermittent agitation. The physicochemical and mechanical properties of the BC films were then investigated by Fourier Transformed Infrared Spectroscopy (FTIR), Thermogravimetry analysis, Field Emission Scanning Electron Microscopy (FE-SEM), and Dynamic mechanical analysis. Agitation gave a higher BC yield, with Komagataeibacter sp. CCUG73629 producing BC from CC with a dry weight of 1.6 g/L and 1.4 g/L under continuous and intermittent agitation, respectively, compared with that of 0.9 g/L in HS medium. While BC yield of dry weight up to 1.2 g/L was obtained from SCB by Komagataeibacter sp. CCUG73630 under continuous agitation compared to that of 0.3 g/L in HS medium. FTIR analysis showed BC bands associated with cellulose I, with high thermal stability. The FE-SEM analysis showed that BC fibers were highly ordered and densely packed. Although the BC produced by both strains showed similar physicochemical and morphological properties, the BC produced by the Komagataeibacter sp. CCUG73630 in CC under intermittent agitation had the best modulus of elasticity, 10.8 GPa and tensile strength, 70.9 MPa.

Design and evaluation of the antimicrobial properties of ackee seed extract silver nanoparticle film formulations.

BACKGROUND: Plant-extract-reduced metal nanoparticles provide means of overcoming microbial resistance. Incorporating them into appropriate pharmaceutical formulations will enhance their portability and ease of administration. OBJECTIVES: To synthesize silver nanoparticles using methanol extracts of the seeds of Blighia sapida as capping agents and formulating the products in antimicrobial films. MATERIAL AND METHODS: Phytochemical screening of the methanol extract of Blighia sapida K.D. Koenig (ackee) seeds was performed and its antioxidant properties were determined using DPPH (1,1-diphenyl-2-picrylhydrazyl) assay. The green synthesis of ackee seed extract silver nanoparticles (ASAgNPs) was accomplished with reacting 1 mM of aqueous silver nitrate (AgNO3) and the methanol extract in a flask; the bioreduction was performed at 37°C for 72 h. The resulting nanoparticles were lyophilized and characterized using UV-visible spectrophotometry, Fourier-transform infrared spectroscopy (FTIR) and photomicrography. The nanoparticles were further formulated into films using starch and carboxymethyl cellulose using the solvent evaporation method. The extract, biosynthesized nanoparticles and film formulations were screened for antimicrobial activity against several pathogens using the agar well diffusion method. RESULTS: The methanol seed extracts of the ackee fruit contained saponins, tannins, flavonoids, terpenoids, and anthraquinones. The extract exhibited significant antioxidant properties. The nanoparticles and film formulations had a broader range of activity against microbes than the plant extract, exhibiting significant activity against Escherichia coli ATCC 700728, Salmonella typhi ATCC 14028, Staphylococcus aureus ATCC 29213, and Pseudomonas aeruginosa ATCC 27853. Activity was also observed with Candida krusei, C. albicans, and Penicillium sp. It is noteworthy that this last organism showed resistance to fluconazole. CONCLUSIONS: Ackee seed extract silver nanoparticles exhibited a synergistic antimicrobial activity against several pathogens. Film formulations of the nanoparticles retained this antimicrobial activity and allowed the product to be presented in a consumer-ready form.

Phytochemical composition and comparative evaluation of antimicrobial activities of the juice extract of citrus aurantifolia and its silver nanoparticles

Background: Citrus aurantifolia juice has been useful for the treatment of various infections and green synthesis of silver nanoparticle using lime juice may offer added advantages.Objective: The phytochemical composition and comparative evaluation of antimicrobial activities of the crude juice extract and biosynthesized Silver nanoparticle (SNPs) from Citrus aurantifolia juice was investigated.Materials and methods: Phytochemical, antimicrobial evaluation (agar well diffusion) and biosynthesis of SNPs was done using Crude extract of Citrus aurantifolia. The SNPs were characterized by colour changes, spectroscopy and Fourier-Transform Infrared (FTIR) Spectroscopy.Results: The juice extract contained bioactive compounds such as flavonoids (710mg/100g), tannins (525mg/100g), phenols (65mg/100g) and terpenes (56mg/100g). Changes in colour, UV-Vis Spectroscopy at 300-550nm ranges and FTIR revealed the functional groups present in the biosynthesized SNPs. The crude extract and SNPs exhibited varying antimicrobial activities against some selected pathogens including Streptococcus pyogenes ATCC 19615, Klebsiella pneumoniae ATCC 10031, Bacillus sp, Actinobacillus sp., Pseudomonas aeruginosa and Staphylococcus aureus. The crude extract has more antibacterial potential against the tested pathogens than the biosynthesized SNPs. The crude extract also had higher antimicrobial activities against Streptococcus pyogenes which were resistant to ciprofloxacin. The result revealed that the crude extract was more effective than the SNPs produced and the Minimum Inhibitory concentration (MIC) also showed increasing activities with an increase in the concentration of the juice extract and SNPs.Conclusion: Crude extract of Citrus aurantifolia contain bioactive compound with potent antimicrobial potential and the extract was more effective than the biosythesized SNPs