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Amplicon-based assessment of bacterial diversity and community structure in three tropical forest soils in Kenya
(Published by Elsevier Ltd., 2022-11-07) Eucharia Kenya, Grace Kinyanjui, Alex Kipnyargis, Franklin Kinyua, Mary Mwangi, Fathiya Khamis, Romano Mwirichia
Forest soils provide a multitude of habitats for diverse communities of bacteria. In this study, we selected three
tropical forests in Kenya to determine the diversity and community structure of soil bacteria inhabiting these
regions. Kakamega and Irangi are rainforests, whereas Gazi Bay harbors mangrove forests. The three natural
forests occupy different altitudinal zones and differ in their environmental characteristics. Soil samples were
collected from a total of 12 sites and soil physicochemical parameters for each sampling site were analyzed. We
used an amplicon-based Illumina high-throughput sequencing approach. Total community DNA was extracted
from individual samples using the phenol-chloroform method. The 16S ribosomal RNA gene segment spanning
the V4 region was amplified using the Illumina MiSeq platform. Diversity indices, rarefaction curves, hierarchical
clustering, principal component analysis (PCA), and non-metric multidimensional scaling (NMDS) analyses were
performed in R software. A total of 13,410 OTUs were observed at 97% sequence similarity. Bacterial communities were dominated by Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria, and Acidobacteria in both
rainforest and mangrove sampling sites. Alpha diversity indices and species richness were higher in Kakamega
and Irangi rainforests compared to mangroves in Gazi Bay. The composition of bacterial communities within and
between the three forests was also significantly differentiated (R ¼ 0.559, p ¼ 0.007). Clustering in both PCA and
NMDS plots showed that each sampling site had a distinct bacterial community profile. The NMDS analysis also
indicated that soil EC, sodium, sulfur, magnesium, boron, and manganese contributed significantly to the
observed variation in the bacterial community structure. Overall, this study demonstrated the presence of diverse
taxa and heterogeneous community structures of soil bacteria inhabiting three tropical forests of Kenya. Our
results also indicated that variation in soil chemical parameters was the major driver of the observed bacterial
diversity and community structure in these forests
OPTIMIZATION OF PARAMETERS FOR BIO-ETHANOL PRODUCTION FROM SWEET SORGHUM (Sorghum bicolor (L.) Moench) STALK JUICE AND FINGER MILLET MALT USING TAGUCHI METHOD
(Bull. Chem. Soc. Ethiop., 2023-11-02) Dolphene Okoth, Stephen Otieno, Francis Kiema, David Onyango and Chrispin Kowenje
ABSTRACT. Bio-ethanol is a promising renewable energy but its production is expensive from high cost of
feedstocks. In this study, sweet sorghum (Sorghum bicolor (L.) Moench) stalk juice was investigated for bio-ethanol
production. Most reports on bio-ethanol productions use commercial Saccharomyces cerevisiae as yeast. However,
this study used finger millet (Eleusine coracana) malt with already high adaptation to local conditions and high
economic viability as it is being utilized by the indigenous communities. Five sweet sorghum varieties of IESV92001-DL (V1), NTJ (V2), 15233-IESV (V3), 92008-DJ (V4) and IESV-92028-DL (V5) were planted at
0°3'45.4644" North, 34°17'16.1052" South, in Kenya. °Brix content of juice was determined at 11th to 16th weeks
after sowing. Highest °Brix for all varieties were at 15th week where V1 was highest at 22.07. V1 was then harvested
for the juice. Factors affecting fermentation; temperature, time, pH and yeast to substrate ratio were optimized using
Taguchi method and were obtained as 30 ℃, 48 hours, pH 5 and 5 g/L, respectively. Kinetics parameters of Vmax
and Km were 0.35 g/L/h and 12.56 g/L, respectively. The optimized and kinetic parameters were within literature
values and therefore finger millet malt has a great potential, as a substitute yeast source, in commercial bio-ethanol
production.
Optimization of Bioethanol Production from Sweet Sorghum Stalk (Sorghum bicolor (l.) Moench) Juice Using Response Surface Method
(science publishing group, 2022-10-30) Purity Ngui, Dolphene Okoth, Stephen Otieno, Bowa Kwach, Patrick Kuloba, David Onyango, Harun Ogindo, Chrispin Kowenje
Abstract: The use of fossil fuel as a source of energy has been unsustainable and has adverse effects to the environment.
Bioethanol is a suitable alternative due to its exceptional properties. Bioethanol production can be done through fermentation
of sucrose in presence of a catalyst and as is customary for every production processes, the fermentation parameters such as the
pH, duration of reaction, the catalyst concentration and the temperature need to be optimized. Thus, this study sought to
optimize bioethanol production parameters from the sweet sorghum stalk juice. Sweet sorghum is potential multipurpose crop
since it can be used as human food, animal feed, animal fodder and processed for syrup and bio-fuel. For this work, Sweet
sorghum stalks were harvested 15 weeks after planting, crushed to extract the juice and the juice fermented in presence of
biocatalyst (Saccharymyes ceresiae). A 44
Factorial design in Minitab 17 software was used to design the experimental runs.
Thereafter, response surface method (SRM) and contour plots were used to determine the best operating conditions among the
applied factorial combination of parameters. It was concluded that the optimal catalyst concentration was 1.5 ± 0.5 g/l,
duration of reaction was 55.25 ± 3.25 hrs., pH was 5.0 ± 0.25 and the temperature was 40 ± 1.0 degrees Celsius. The chemical
composition of the produced bioethanol indicated that it is a good substitute for combustion engine fuel. Thus, the bioethanol
has the potential to replace the fossil gasoline as a fuel hence being friendlier to the environment.
PROXIMATE COMPOSITION AND NUTRITIONAL CHARACTERIZATION OF CHIA ENRICHED YOGHURT
(African journal of food agriculture, nutrition and development (AJFAND), 2018-04) Kibui AN, Owaga E and M Mburu
Yoghurt is a fermented dairy product associated with several beneficial nutritional and
health effects. Due to increased demand of yoghurt in Kenya, some processors seek to
incorporate synthetic ingredients in order to improve the nutritional value, thickening
and stabilizing properties. Besides having good gelling properties, chia seeds (Salvia
hispanica L.) are a good source of proteins, omega-3 fatty acids, omega-6 fatty acids,
minerals, soluble dietary fiber and phytochemicals. This study sought to develop and
determine the proximate composition and nutritional (amino acids, fatty acids, and
mineral contents) characteristics of chia enriched yoghurt (CEY). Yoghurt treatments
were enriched with chia seeds at either 1.5% m/v (CEY1.5), 2.5% m/v (CEY2.5) or 3.5%
m/v (CEY3.5), and 2% cornstarch (CEY0). The results of the proximate composition
indicated a significantly higher content of moisture, crude ash, crude fat, crude fiber and
carbohydrates in CEY1.5, CEY2.5 and CEY3.5 than in CEY0. In the current study, the
composition of calcium, potassium, and phosphorus, was significantly higher in CEY
1.5, CEY2.5 and CEY3.5 than in CEY0, with values increasing with increase in quantity
of chia seeds in the formulation. The results for amino acids showed that the essential
and non-essential amino acids were significantly higher in CEY3.5 than CEY2.5,
CEY2.5 than CEY1.5 and CEY1.5 than CEY0. In terms of fatty acids profile, the
concentration of lauric acid and palmitic acid was significantly lower in CEY1.5,
CEY2.5 and CEY3.5 than in CEY0. On the other hand, the concentration of stearic acid,
oleic acid, linoleic acid and α-linolenic acid in CEY1.5, CEY2.5 and CEY3.5 was
significantly higher than in CEY0. In conclusion, CEY1.5, CEY2.5 and CEY3.5 showed
enhanced proximate composition and nutritional (amino acids, fatty acids, and minerals
contents) characteristics compared to CEY0, thus chia seeds have a potential to be used
in yoghurt for value addition.
The Economic, Health and Nutritional benefits of Chia (Salvia hispanica L.) Farming In Nyeri County, Kenya – Baseline survey analysis.
(2019-04-02) David M. Gitau, Dr. Monica Mburu, Dr. David Kiarie
Descriptive cross-sectional survey was conducted to provide quantitative information on the current
status of chia cultivation in Nyeri County. This aimed at assessing the opportunities and challenges in chia
cultivation in Nyeri County, Kenya. It involved the systematic collection and presentation of data to give a clear
picture of awareness, knowledge, attitude and practices (AKAP) of the selected population. This was done as the
preliminaries to promotion of chia cultivation and value chain development in the region. Having the
beneficiaries participate in the assessment of needs and identification of problems to be addressed helps to
accommodate their information, experience and analysis therefore making them actual creators of change and
progress. This will result in improved involvement of target beneficiaries who will participate in the
implementation of an effective and beneficial chia value chain.The baseline study expressed findings in a
quantitative manner providing justification for promotion of chia production in the region, and guide the
selection of most appropriate traditional and modern media to be used in a in project implementation. The
results will be used as a reference point or benchmark for later comparison or impact studies to assess how well
the original project objectives have been achieved. The results can also be generalized and used for similar
project in other regions of Kenya.
