Characterization of Autochthonous Lactic Acid Bacteria Isolated from a Traditional Ethiopian Beverage, Tella.

This study aimed to isolate lactic acid bacteria (LAB) from a traditional Ethiopian fermented product, Tella, and evaluate their functional properties. Of forty-three isolates, seven LAB were screened and identified as Pediococcus pentosaceus, Latilactobacillus curvatus, Leuconostoc mesenteroides, and Lactiplantibacillus plantarum species. The isolates were tested for their alcohol tolerance, acid and bile resistance, auto-aggregation, co-aggregation, hydrophobicity, antibacterial activity, and antibiotic susceptibility. LAB isolates, specifically P. pentosaceus TAA01, L. mesenteroides TDB22, and L. plantarum TDM41, showed a higher degree of alcohol tolerance in 8% and 10% (w/v) ethanol concentrations. Additionally, these three isolates displayed survival rates >85% in both acidic pH and bile environments. Among the isolates, L. plantarum TDM41 demonstrated the highest auto-aggregation, co-aggregation, and hydrophobicity with (44.9 ± 1.7)%, (41.4 ± 0.2)%, and (52.1 ± 0.1)% values, respectively. The cell-free supernatant of the isolates exhibited antibacterial activity against foodborne pathogens of Escherichia coli, Salmonella Enteritidis, and Staphylococcus aureus. Each isolate exhibited various levels of resistance and susceptibility to seven antibiotics and resistance was observed against four of the antibiotics tested. After performing a principal component analysis, Pediococcus pentosaceus TAA01, L. mesenteroides TDB22, and L. plantarum TDM41 were selected as the most promising ethanol-tolerant probiotic isolates.

Catalytic Performance Investigation of Alkali and Bifunctional Catalysts Derived from Lignocellulosic Biomasses for Biodiesel Synthesis from Waste Frying Oil.

In this study, alkali and bifunctional catalysts were synthesized for waste frying oil methyl ester (WFOME) synthesis. Coffee husk (CH) and CH blended with Eragrostis tef straw (TS) (CH-TS) lignocellulosic biomasses (LBs) were utilized during the catalysts' synthesis. The alkali catalysts were CH and CH-TS ashes, both modified by KNO3 impregnation. They are designated as C-45 and C-Mix, respectively. Zirconia (ZrO2) promoted CH ash catalysts via precipitation followed by impregnation (Bic-PP) and in situ precipitation-impregnation (Bic-Dm) were the bifunctional ones. CH and CH-TS chars were the supporting frameworks during the catalysts' composite materials (CCMs) preparation. The combustion performance of LBs and CCMs was evaluated and associated with the catalysts' physicochemical properties. Using XRD, SEM, FTIR, alkalinity, TOF, and BET surface area analysis, catalysts were characterized. The combustion performance of the LBs was in the order of TS > CH-TS > CH. Among CCMs, the highest combustion performance was for CCM-Mix (KNO3/(CH-TS char)) and the lowest was for CCM-45 (KNO3/ CH char). The C-Mix catalyst was a light green powder due to the reaction between inorganic components, whereas C-45 was dark gray due to the presence of unburned char. The CCMs for bifunctional catalysts had moderate combustion performance and yielded light gray powdered catalysts containing tetragonal ZrO2. The optimum WFOME yields were 98.08, 97, 92.69, and 93.05 wt % for C-Mix, C-45, Bic-Dm, and Bic-PP assisted WFO transesterification, respectively. The results were obtained at a reaction temperature of 65 °C, time of 1 h, and methanol to WFO molar ratio of 15:1 using catalyst amounts of 5 and 7 wt % for the alkali and bifunctional catalysts, respectively. The greatest moisture resistance was offered by the C-Mix catalyst. The best reusability was for the C-45 catalyst. Catalysts' deactivation modes include active site leaching and poisoning.

KNO3-Loaded Coffee Husk Ash as a Heterogeneous Alkali Catalyst for Waste Frying Oil Valorization into Biodiesel.

In this study, a heterogeneous basic catalyst was synthesized from a catalyst composite material (CCM) of coffee husk ash and char mixture (A/C) impregnated with KNO3 and employed to transesterify crude waste frying oil (WFO). The effect of CCM calcination temperature (CCMCT) (500-700 °C) on the catalyst physicochemical properties was investigated. A differential scanning calorimeter was used to examine potential phase changes during the calcination of A/C and CCM. The catalysts from each CCMCT were characterized by X-ray diffraction (XRD), Brunauer-Emmet-Teller surface area analyzer, scanning electron microscopy (SEM), SEM with energy-dispersive X-ray diffractometer, colorimeter, and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectrometer. The methoxy functional group FTIR peak integral value and the dynamic viscosity of the biodiesel synthesized by each catalyst were used to determine the qualitative WFO conversion. Furthermore, the quantitative WFO conversion was determined using nuclear magnetic resonance (1H NMR) analysis. Crystallinity, elemental composition, basicity, and morphology of catalysts were highly dependent on the CCMCT. Without transesterification condition optimization (reaction temperature of 45 ± 2.5 °C, catalyst loading of 3 wt %, methanol to oil molar ratio of 12:1, and reaction time of 1 h), a higher catalytic performance (72.04% WFO conversion) was reached using a catalyst from the CCMCT of 600 °C. When using a coffee husk ash catalyst without KNO3 impregnation (C-00-600), the WFO conversion was only 52.92%. When comparing the C-25-600 and C-00-600 catalysts, it was observed that KNO3 impregnation had a substantial impact on the catalyst crystallinity, basicity, and morphology.