Statistical versus neural network-embedded swarm intelligence optimization of a metallo-neutral-protease production: activity kinetics and food industry applications.

An integrated approach involving response surface methodology (RSM) and artificial neural network-ant-colony hybrid optimization (ANN-ACO) was adopted to develop a bioprocess medium to increase the yield of Bacillus cereus neutral protease under submerged fermentation conditions. The ANN-ACO model was comparatively superior (predicted r2 = 98.5%, mean squared error [MSE] = 0.0353) to RSM model (predicted r2 = 86.4%, MSE = 23.85) in predictive capability arising from its low performance error. The hybrid model recommended a medium containing (gL-1) molasses 45.00, urea 9.81, casein 25.45, Ca2+ 1.23, Zn2+ 0.021, Mn2+ 0.020, and 4.45% (vv-1) inoculum, for a 6.75-fold increase in protease activity from a baseline of 76.63 UmL-1. Yield was further increased in a 5-L bioreactor to a final volumetric productivity of 3.472 mg(Lh)-1. The 10.0-fold purified 46.6-kDa-enzyme had maximum activity at pH 6.5, 45-55 °C, with Km of 6.92 mM, Vmax of 769.23 µmolmL-1 min-1, kcat of 28.49 s-1, and kcat/Km of 4.117 × 103 M-1 s-1, at 45 °C, pH 6.5. The enzyme was stabilized by Ca2+, activated by Zn2+ but inhibited by EDTA suggesting that it was a metallo-protease. The biomolecule significantly clarified orange and pineapple juices indicating its food industry application.

Production, characterization, and bio-ethanologenic potential of a novel tripartite raw starch-digesting amylase from Priestia flexa UCCM 00132.

The biological conversion of agro-waste biomass into value-added metabolites is one of the trendy biotechnological research areas in recent times. One of the major drawbacks of the bioprocess is the saccharification potential of the amylolytic enzyme that releases reducing sugar from complex biomass to serve as substrate for fermentation. The present study reports the production of a novel tripartite raw starch-digesting amylase (RSDA) by an indigenous Priestia flexa strain with α-, ß-, and gluco-amylolytic activities and its potential for bioethanol production. Response surface statistics was employed to develop a suitable medium for improved production of the tripartite enzyme by submerged fermentation. The bioprocess selected raw starch (4.36%) Ca2+(2.71 g/L) and Zn2+ (0.0177 g/L) as significant variables which demonstrated a total RSDA activity of 7208.23 U/mL in a 5-L batch bioreactor. SDS/Native-PAGE determined the molecular weights of the 27-fold purified product as 25.2 kDa, 57.3 kDa, and 90.1 kDa for α-, ß-, and gluco-amylases, respectively. Optimum temperature and pH for enzyme activity were respectively broad at 30-70 °C and 4-11. The enzyme mixture demonstrated digestibility above 90% against a variety of raw starches and simultaneous fermentation of digestate with Saccharomyces cerevisiae generated 71.69 g/L of bioethanol within 24 h suggesting great potential for bioethanologenesis.

Studies on plasmids of multidrug resistant uropathogens isolated from patients with urinary tract infection in a tertiary hospital in Calabar, Nigeria.

Background: Urinary tract Infections caused by multidrug resistant uropathogens have become a significant global public health problem with Nigeria being no exception. Objective: This study is aimed at profiling and curing the plasmids of selected multidrug resistant uropathogens isolated from patients with urinary tract infection in a tertiary hospital in Calabar, Nigeria. Methodology: Isolates were obtained from urine samples of patients using standard microbiological techniques. Multidrug resistant bacterial isolates were then selected for plasmid DNA analysis and curing. Results: The study revealed that E. coli, K. pneumoniae, P. aeruginosa and Proteus mirabilis were resistant to the antibiotics tested. The extracted plasmid DNA showed the presence of TEM, SHV and CTX-M genes in the isolates with sizes of 400-600bp, 300bp and 500-800bp, respectively. All isolates possessed the SHV genes while few had TEM and CTX-M genes. Cells were subjected to curing and plasmid curing was achieved at 200-300µl of ethidium bromide. Conclusion: The reduction in percentage resistance due to plasmid curing observed in this study suggests that the resistance of the isolates to antibiotics were plasmid-mediated. Antibiogram and monitoring of plasmid mediated resistance are necessary for proper management of urinary tract infections.

Plackett-Burman Design and Response Surface Optimization of Medium Trace Nutrients for Glycolipopeptide Biosurfactant Production

Background: A glycolipopeptide biosurfactant produced by Pseudomonas aeruginosa strain IKW1 reduced the surface tension of fermentation broth from 71.31 to 24.62 dynes/cm at a critical micelle concentration of 20.80 mg/L. The compound proved suitable for applications in emulsion stabilization in food, as well as in cosmetic and pharmaceutical formulations. Method: In the present study, Plackett-Burman design (PBD) and response surface method (RSM) were employed to screen and optimize concentrations of trace nutrients in the fermentation medium, to increase surfactant yield. Results: The PBD selected 5 out of the 12 screened significant trace nutrients. The RSM, on the other hand, resulted in the production of 84.44 g glycolipopeptide/L in the optimized medium containing 1.25 mg/L nickel, 0.125 mg/L zinc, 0.075 mg/L iron, 0.0104 mg/L boron, and 0.025 mg/L copper. Conclusion: Significant second-order quadratic models for biomass (P<0.05; adjusted R2=94.29%) and biosurfactant (R2=99.44%) responses suggest excellent goodness-of-fit of the models. However, their respective non-significant lack-of-fit (Biomass: F=1.28; P=0.418; Biosurfactant: F=1.20; P=0.446) test results indicate their adequacy to explain data variations in the experimental region. The glycolipopeptide is recommended for the formulation of inexpensive pharmaceutical products that require surface-active compounds.