Bacteriocins produced by various lactic acid bacteria (LAB) have found enormous use in the food industries as biopreservatives. This study evaluated the effect of varied culture conditions (temperature, pH, and NaCl concentration) on bacteriocin production by Lactococcus lactis MT186647 isolated from fermenting African oil bean seeds (Pentaclethra macrophylla Benth) using response surface methodology. A three-factor central composite design (CCD) was adopted with the interest of estimating the optimal conditions for its production using the response surface regression model, which evaluated the linear, squared, and interactive relationship between the response variables. The analysis of variance (ANOVA) using Minitab statistical software version 14.13 showed an R2 = 0.869 variations in the response variable for culture conditions. It was accounted for by the predictors suggesting that the model was adequate. The optimal culture condition for bacteriocin production by L. lactis was estimated at 30.5C, pH 5.9, 1.94% NaCl concentration at Y = 12.31 mm where Y represents the response (zone of inhibition) against Staphylococcus aureus ATCC 19095 using the agar well diffusion assay method. Validation of optimal values according to the regression model, produced an inhibition zone at Y = 13.33 ± 0.29 mm. There was a 19.33% increase in bacteriocin activity compared to an OFAT optimized medium from a previous study.

The enzymatic hydrolysis of wood particles and sawdust (waste) and fermentation of resultant sugar to produce bio-ethanol is both economical and efficient. Sawdust and wood particles contains high amount of cellulose which needs to be broken down to simple sugar (glucose) and fermented to produce ethanol. Trichoderma viride with high enzymatic (cellulase) activity was used to hydrolyse the processed wood particles and sawdust for 5 to 7 days after which the presence of reducing sugar was determined using Fehling's and Anthrone method. The determined sugar (%) of 6.87±0.25 was optimized to 23.90±0.18 by adding commercial sugar. After optimization, the hydrolysate was inoculated with Saccharomyces cerevisiae isolated from palm wine and left to ferment for 7 days. During the fermentation, changes in physicochemical properties such as temperature, pH, titratable acidity, sugar content, specific gravity, biomass and ethanol yield were monitored. The temperature fluctuated between 29 oC and 30 oC with pH decreasing from 5.8 to 4.1, generating a biomass yield of 1.98±0.21 g/L. The sugar content (%) reduced from 23.90±0.18 to 3.83±0.32 and 10.16±0.12 ethanol (%) was obtained at the end of the fermentation. Therefore, it is clearly evident that wood particles and sawdust are potential substrates for the production of ethanol, and extending fermentation days could lead to a higher ethanol yield.

Bacteriocin production by lactic acid bacteria (LAB) is strongly conditioned by growth-medium composition, and adjusting ingredients offers a low-cost route to enhanced yield. Response surface methodology (RSM) based on a three-factor, five-level central composite design (CCD) was used to optimize supplementation of an African oil bean seed ( Pentaclethra macrophylla Benth) extract broth with glucose, sodium citrate and potassium chloride for two LAB isolated from the seed and identified by 16S rRNA sequencing, Lactococcus lactis MT186647 and Lactobacillus fermentum MT186598. Twenty runs per organism were performed; bacteriocin activity was determined by the zone of inhibition against Staphylococcus aureus ATCC 19095 by agar well diffusion. For both isolates, glucose exerted a significant negative linear effect and all three supplements significant negative quadratic effects, while no two-factor interaction reached significance, indicating an additive response. The second-order models accounted for 71.85% ( L. lactis ; p = 0.060) and 73.15% ( L. fermentum ; p = 0.050) of the variation, with significant lack-of-fit; the regression was therefore only marginally significant, and the predicted R² was 0.00%, indicating no demonstrated ability to predict new runs. The desirability-based optima (6.35/0.55/1.78 g/L glucose/sodium citrate/potassium chloride for L. lactis ; 6.44/0.55/1.59 g/L for L. fermentum ; predicted zones 13.12 and 12.74 mm) are best interpreted as an estimated optimal region rather than a quantitatively predictive optimum. Validation under these optima combined with the previously established optimal culture conditions (1.9% NaCl, 31 °C, initial pH 6.0) produced zones of 15.22 mm ( L. lactis ) and 14.96 mm ( L. fermentum ), exceeding the supplementation-only model estimates by 16.0% and 17.4% and the previously reported culture-condition-only outcomes (13.33 and 11.75 mm) by 14.2% and 27.3%. Because these differences were not tested statistically and partly reflect the fixed 1.9% NaCl (optimized separately and absent from the supplement CCD), the two optimization layers are interpreted as combining additively rather than demonstrating an established synergy. Moderate, balanced supplementation with inexpensive, food-grade additives can substantially enhance bacteriocin yield, supporting further development, subject to confirmatory multi-point validation, of L. lactis MT186647 and L. fermentum MT186598 as starter or protective cultures for the controlled fermentation of P. macrophylla to Ugba .