School of Pure and Applied Sciences
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Item Prokaryotic diversity and composition within equatorial lakes Olbolosat and Oloiden in Kenya (Africa)(ELSEVIER :www.sciencedirect.com/journal/current-research-in-microbial-sciences, 2021-12-26) Wafula, Eliud N.; et.alTotal community 16S rDNA was used to determine the diversity and composition of bacteria and archaea within lakes Olbolosat and Oloiden in Kenya. The V3-V4 hypervariable region of the 16S rRNA gene was targeted since it’s highly conserved and has a higher resolution for lower rank taxa. High throughput sequencing was performed on 15 samples obtained from the two lakes using the Illumina Miseq platform. Lakes Olbolosat and Oloiden shared 280 of 10,523 Amplicon Sequence Variants (ASVs) recovered while the four sample types (water, mi crobial mats, dry and wet sediments) shared 4 ASVs. The composition of ASVs in lake Olbolosat was highly dependent on Cu+, Fe2+, NH4+, and Mn2+, while L. Oloiden was dependent on Mg2+, Na+, Ca2+, and K+. All the alpha diversity indices except Simpson were highest in the dry sediment sample (EC1 and 2) both from lake Oloiden. The abundant phyla included Proteobacteria (33.8%), Firmicutes (27.3%), Actinobacteriota (21.2%), Chloroflexi (6.8%), Cyanobacteria (3.8%), Acidobacteriota (2.8%), Planctomycetota (1.9%) and Bacteroidota (1.1%). Analysis of similarity (ANOSIM) revealed a significant difference in ASV composition between the two lakes (r =0.191, p =0.048), and between the sample types (r =0.6667, p =0.001). The interaction network for prokaryotic communities within the two lakes displayed Proteobacteria to be highly positively connected with other microbes. PERMANOVA results suggest that temperature controls the functioning of the two ecosystems.Item Potential Role of African Fermented Indigenous Vegetables in Maternal and Child Nutrition in Sub-Saharan Afric(Hindawi International Journal of Food Science, 2021-12-15) Wafula, Eliud N.; et.alHunger and malnutrition continue to affect Africa especially the vulnerable children and women in reproductive age. However, Africa has indigenous foods and associated traditional technologies that can contribute to alleviation of hunger, malnutrition, and communicable and noncommunicable diseases. The importance of African indigenous vegetables is undeniable, only that they are season-linked and considered as “food for poor” despite their high nutritional contents. The utilization of African indigenous vegetables (AIVs) is hindered by postharvest losses and antinutrients affecting the bioavailability of nutrients. In Africa, fermentation is among the oldest food processing technologies with long history of safe use. Apart from extending shelf life and improving food organoleptic properties, fermentation of African indigenous vegetables (AIVs) is known to improve food nutritional values such as proteins, minerals, vitamins, and other beneficial phytochemicals. It can also increase bioavailability of various vitamins, minerals, and phytochemicals and increase synthesis of vital blood pressure regulators thus protecting against cardiovascular diseases and cancer and further helping fight certain malnutrition deficiencies. Some lactic acid bacteria (LAB) involved in food fermentation are known to produce exopolysaccharides with cholesterol-lowering, immunomodulator, antioxidant, and anticancer properties. Fermented foods (vegetables) are superior in quality and safety since most microorganisms involved in fermentation are good starter cultures that can inhibit the growth of foodborne pathogens and detoxify harmful compounds in foods. Thus, fermented foods can boost growth and well-being in children and women due to their higher nutritional contents. Therefore, fermentation of AIVs can contribute to the attainment of food and nutrition security especially among women and children who rely on these vegetables as a staple source of micronutrients and income. These benefits have a positive impact on the implementation of the second sustainable development goals and African Union agenda 2063. This review is aimed at shedding light on the potential of African fermented indigenous vegetables in combating maternal and child malnutrition in Sub-Sahara AfricaItem Phenotypic and genotypic characterization of lactic acid bacteria isolated from spontaneously fermented vegetable amaranth(African Journal of Food Science, 2021-05-25) Wafula, Eliud N.; et.alLactic acid bacteria (LAB) are Gram-positive, non-spore-forming, catalase-negative cocci or rod-shaped bacteria that produce lactic acid as a major fermentation product. They are also involved in the production of fermented foods. They have applications in industry and human health, such as food preservation and probiotics. The aim of this research was to isolate, characterize, and classify indigenous lactic acid bacteria from fermented vegetable amaranth, a leafy vegetable native to Africa. The isolates' 16S rRNA gene was amplified using bacterial universal primers 27F and 1492R. From fermented vegetable amaranth, a total of 15 LAB were isolated were grouped into the genera Lactobacillus, Lactococcus, and Weissella based on 16S rRNA gene analyses. Lactobacillus plantarum dominated vegetable amaranth fermentation, accounting for 60% of all isolates.Item Isolation and Identification of Bacteriocin-Producing Bacillus spp from Rastrineobola argentea (Omena) with Activity against Bovine Mastitis Bacterial Pathogens(Journal of Food Security, 2021-04-19) Wafula, Eliud N.; et.alRampant use of antibiotics has increased resistance of pathogenic bacteria in both animals and humans. This has triggered the investigation of novel antimicrobial agents produced by a bacterial strain of low virulence with antimicrobial activity with a wide range of clinical significance. This study sought to extract bacteriocins from Bacillus spp that were isolated and identified from Omena (Rastrineobola argentea) and to evaluate the in vitro antimicrobial effect of the obtained bacteriocin against bovine mastitis pathogens. Samples were collected from Lake Victoria using a completely randomized design method followed by isolation of the bacteriocin producing Bacillus spp. Characterization and identification of isolates was done by Gram staining, morphology and Biochemical tests which included catalase, nitrate reduction, methyl Red,-Voges-Proskauer, indole, motility and hydrogen sulphide, growth on Simmons citrate agar, triple sugar iron agar and starch hydrolysis. Antimicrobial activity was done using disc diffusion methods on the nutrient agar and zone of the inhibition measured after 24hours. An analytical profile index system (API 50CH BE, Biomerieux, Inc, France), was also used for identification. Molecular characterization was done by extracting genomic DNA using Qiagen DNA isolation Kit (Qiagen Germany) using the manufacturer's instructions. The gene encoding the 16S rRNA was amplified by PCR using universal bacterial primers pair combination of forwarding primer 27F forward (5′-AGA GTT TGA TCC TGG CTC AG-3′) and 1492R reverse, (5′-GGT TAC CTT GTT ACG ACT T-3′) about Escherichia coli gene sequence. A total of 60 pure isolates were obtained from Omena samples from Lake. Victoria. Morphological characteristics showed varied colour, form, shape and elevation of the pure colonies. About 54 isolates (90%) were gram-positive with spores, while 6 (10%) were gram-negative. Biochemical tests showed varied results among the bacterial isolates. 28 isolates showed antimicrobial activity on E. coli and S. aureus with inhibition measuring between 17-30mm. Analytical profile index system also showed that 20 isolates (71%) were identified as Bacillus subtilis, three isolates (11%) identified as Bacillus pumilus and five isolates (18%) Bacillus mycoides. The Blast analysis of the partial sequences showed100% of the strains of genus Bacillus within the Firmicutes in the domain bacteria. Twenty (20) isolates belong to Bacillus subtilis, Bacillus mycoides represent 18% (5 isolates) while Bacillus pumilus constituted 11% (3 isolates). This study contributes to understanding the use of bacteriocin in the control of diseases in dairy animal farming in Kenya.Item Isolation and Characterization of Bacteria from Lakes Olbolosat and Oloiden, Kenya(African Journal of Microbiology Research, 2021-01-26) Wafula, Eliud N.; et.alThere is still unexplored reservoir of microorganisms from sediments and water within Lakes Olbolosat and Oloiden using culture dependent technique. The current study compares bacterial diversity within Lake Olbolosat a freshwater lake and Lake Oloiden a saline alkaline lake. Out of 60 isolates obtained from sediments and water samples, 35 were from Lake Olbolosat and 25 from Lake Oloiden. Microbial count ranged between 0-1.75× 105 cfu/ml from both lakes. There was a significant difference between bacterial density and sampling points (p<0.001, F=6.667), 58 were Gram-positive and 2 Gram-negative. Fifty-five isolates that were rod-shaped, 3 were cocci and 2 filamentous. There was excellent growth of isolates at an optimum growth pH range of 6-10, a temperature range of 25-30°C and a salinity range of 0-5%. There was significant difference at p<0.001 for bacterial growth within physiological parameters. The isolates utilized skimmed milk, starch, olive oil, cellulose powder and xylan, hence the production of extracellular enzymes. There was antimicrobial activity against Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Candida albicans by bacterial isolates. BLAST analysis of partial sequences showed there were 4 different phyla. Firmicutes scored 77% closely affiliated with 20 strains, Actinobacteria scored 15% closely affiliated with 4 strains, Proteobacteria and Bacteroidetes scored 4% affiliated with 1 strain each. Novel bacteria from this study could provide insights into their diversity and biotechnological applications.Item Fermentation of African nightshade leaves with lactic acid bacterial starter cultures(International Journal of Food Microbiology, 2021-01-04) Wafula, Eliud N.; et.alThe interest in the consumption of African indigenous leafy vegetables increased in African countries, e.g. Kenya, within the last years. One example of African indigenous leafy vegetables is African nightshade (Solanum sca brum) which is nutritious, rich in proteins and micronutrients and therefore could contribute to a healthy diet. African nightshade has several agricultural advantages. However, the most important disadvantage is the fast perishability which leads to enormous post-harvest losses. In this study, we investigated the fermentation of African nightshade as a post-harvest processing method to reduce post-harvest losses. The two lactic acid bac terial starter strains Lactiplantibacillus plantarum BFE 5092 and Limosilactobacillus fermentum BFE 6620 were used to inoculate fermentations of African nightshade leaves with initial counts of 106–107 cfu/ml. Uninoculated controls were conducted for each fermentation trial. Fermentations were performed both in Kenya and in Ger many. The success of the inoculated starter cultures was proven by the measurement of pH values and deter mination of lactic acid concentration. Lactobacilli strains dominated the microbiota of the starter inoculated samples in contrast to the non-inoculated controls. This was supported by classical culture-dependent plating on different microbiological media as well as by the culture-independent molecular biological methods denaturing gradient gel electrophoresis and 16S rRNA gene high-throughput amplicon sequencing. We could demonstrate that the use of the selected starter cultures for fermentation of African nightshade leaves led to controlled and reliable fermentations with quick acidification. Thus, controlled fermentation with appropriate starter cultures is a promising method for post-harvest treatment of African nightshade leaves.Item Antimicrobial Activity and Characteristics of Bacteriocin Producing Bacillus subtilis against Mastitis Pathogens(American Journal of Food Science and Technology, 2021-04-20) Wafula, Eliud N.; et.alThe use of drugs and antibiotics has increased the resistance of pathogenic bacteria in both animals and humans. This has been a significant problem and therefore triggers the investigation of novel antimicrobial agents produced by a bacterial strain of low virulence and having antimicrobial activity with a wide range of clinical significance. The use of bacteriocin has been extensively used in food industries, animals, and pharmaceutical industries. This is because it has been linked to antimicrobial activity, which has specific self-protection mechanisms. This study sought to evaluate antimicrobial activity and characteristics of bacteriocin producing Bacillus subtilis against Mastitis pathogens. For the screening of the isolates for bacteriocin properties against mastitis pathogens, antimicrobial activity was done using well diffusion methods on the nutrient agar. The results were obtained after 24hours and 48hours. Physiochemical characterization of the bacteriocin from Bacillus subtilis was determined at different temperatures of 60°C to 121°C for 15 minutes and monitor the effect of the temperature. The bacteriocin was also prepared at different pH (3-9) and incubated at room temperature; each sample's residual activity was determined against the indicator organisms. Metal ions (Cu2+, Zn2+, and Fe2+) on crude bacteriocin activity were determined to assess the residual antimicrobial activity by agar well diffusion assay. The results showed that bacteriocins from Bacillus subtilis were effective against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumonia. Physiochemical characterization showed that bacteriocin from different isolates had no inhibition from pH 3-5 and varied inhibition from pH 6-9 across the test organisms' isolates. On the temperature, crude bacteriocins at a temperature of 50°C to 60°C showed no activity loss based on initial activity. As temperature increases to 70°C to 80°C, there is reduced the bacteriocin activity of about 20%. 100°C had a 40% loss of the bacteriocin activity and 121°C with more than 50% loss of the activity. On metal ions, Cu2+, Fe2+, Zn2+ had a varied effect on bacteriocin activity against test organisms.Item Seasonal Population Trends of Microbial Communities in Oil Tainted Soils in Greater Port Harcourt Area, Nigeria(Science Publishing Group, 2024-02-20) Wanjala Paul Muyoma; Wafula, Eliud N.; et.alThe utilization of oil in industries has devastating effect to the environment. Industrial effluents and oil spills are continuously contaminating the soil. Further, seasonality influences the distribution of pollutants in soil. Consequently, soil microbial biota and ecological processes are affected. This study assessed the effect of seasonality on soil fungal and bacterial communities in oil contaminated soils in 12 selected sites in Greater Port Harcourt Area. Standard analytical procedures were used to obtain bio-physicochemical data from the soil samples and t test was used to analyse data. The levels of total petroleum hydrocarbons (TPH) were above 5000 ppm (DPR recommended limit). There was significant difference (p ≤ 0.000) between the means of TPH in wet and dry seasons. Seasonality influenced % HUF and % HUB in the soils of urban, industrial and agricultural sites. Generally, the seasonality trends showed that there was a declining population of THB, HUB, TF, and HUF from the wet season to the dry season. However, the results show that there was a stable trend in % HUB as compared to oscillations observed in % HUF in oil tainted soils across a seasonal divide. We recommend characterization of the microorganism to identify the best candidate for bioremediation of oil tainted soils across a seasonal divide.Item Screening and Identification of Diesel Biodegrading Bacteria Isolated From Petroleum Hydrocarbon Contaminated Garage Soils of Kericho County, Kenya(International Journal of Microbiology, 2025-12-24) Wafula, Eliud N.; et.alDespite the benefits of petroleum hydrocarbon as essential raw energy sources in many industries, they cause major global environmental pollution. Petroleum hydrocarbons pollutants are highly toxic and recalcitrant, making them dangerous and persistent over long periods in an ecosystem. However, oil contaminated soil is enriched with microorganisms that can uti lize petroleum products and hydrocarbons for their growth, nutrition, and metabolic activities. This study aimed to isolate and characterize hydrocarbons-degrading bacteria capable of degrading hydrocarbons in soil samples obtained from oil-polluted garage sites in Kericho County, Kenya. One hundred and ten (110) bacterial isolates were isolated after enrichment, with 67 of the isolates (60.9%) having visible petroleum diesel-degrading capability. The bacteria were characterized based on pheno typic characteristics and 16S rRNA gene sequence analyses. Forty-nine of the isolates were Gram negative rods, and majority (56) of the isolates reacted positively for catalase and negatively for oxidase (38), methyl red (59), and Voges Proskauer (65); 50.9% of the isolates tested positive for citrate utilization. More than half of the isolated bacteria (69.7%) demonstrated strong evidence of diesel degradation. Bacteria with moderate diesel degradation demonstration accounted for 18.2% of the isolates, while isolates with substantial diesel residues contributed 12.1%. Following 16S rRNA gene sequence analysis, the bacterial strains were identified as belonging to the genera Acinetobacter (8), Pseudarthrobacter (4), Corynebacterium (2), Gordonia (2), Athrobacter (2), Microbacterium (2), Acidivorax (1), Pseudoxanthomonas (1), Priestia (1), Cellulosimicrobium (1), Cupriavidus (1), Paenarthrobacter (1), Exiguobacterium (1), Shewanella (1), Stutzerimonas (1), and Pseudomonas (1). This study has demonstrated that garage soils with petroleum hydrocarbon contamination in Kericho County harbor a rich and diverse indigenous population of microbes with the ability to biodegrade diesel. The findings suggest potential application of these bacterial strains to facilitate the biodegradation of petroleum hydrocarbons.Item MICROBIAL, CHEMICAL AND SENSORY PROPERTIES OF PINEAPPLE AND BEETROOT JUICE BLEND FERMENTED USING MIXED PROBIOTIC LACTIC ACID BACTERIA CULTURES (LACTOBACILLUS PLANTARUM AND L. RHAMNOSUS)(African journal of food, Agriculture,Nutrition and development ajfand, 2025-11-06) Wafula, Eliud N.; et.alThe rising demand for functional foods has increased interest in probiotic products beyond traditional dairy sources, particularly among individuals with lactose intolerance, dairy allergies, or those adhering to plant-based diets. Fruit juices such as pineapple and beetroot offer promising non-dairy alternatives for delivering probiotic cultures. This study aimed to analyze the microbial, physicochemical, nutritional, and sensory acceptability profiles of pineapple and beetroot juice blends fermented with a mixed culture of probiotic lactic acid bacteria (Lactobacillus plantarum and Lactobacillus rhamnosus). Juice blends were prepared in varying pineapple-to-beetroot ratios: 90:10 (P90:B10), 80:20 (P80:B20) and 70:30 (P70:B30), alongside 100% pineapple (control-P) and 100% beetroot (Br) juices. All blends were pasteurized and inoculated with the probiotic cultures and fermented for 28 days, except the control-P and 100% Br treatment, which underwent spontaneous fermentation. Lactic acid bacteria (LAB) count analysis showed that all inoculated blends maintained probiotic viability (>7 log CFU/mL) for up to 21 days, with the P90:B10 blend maintaining viability up to 28 days. Yeast or mold growth was not detected in the probiotic blends up to day 21, whereas the control-P and 100%Br treatment exceeded yeast and mold count limits by day 14. Physicochemical analysis for all treatments revealed a significant increase in titratable acidity, accompanied by a decrease in pH and sugar content over the fermentation period in the inoculated blends (P90:B10, P80:B20, P70:B30). Significant differences P < 0.05 in vitamin C content were observed between the control-P and all other treatments on day 1. Among the three blends, P90:B10 achieved the highest overall consumer acceptability. Fermenting pineapple-beetroot juice blends with L. plantarum and L. rhamnosus mixed culture is a feasible approach to producing a safe, palatable, and nutritionally beneficial non-dairy probiotic beverage. The P90:B10 blend was optimal in supporting probiotic viability and achieving desirable consumer sensory attributes and, therefore, would be recommended for future commercialization as a probiotic non-dairy product.