Effects of water hyacinth (Eichhornia crassipes [mart.] solms) compost on growth and yield of common beans (Phaseolus vulgaris) in Lake Victoria Basin

ABSTRACT Water hyacinth (Eichhornia crassipes) has become a problem in water bodie

Effects of grain source and processing methods on the nutritional profile and digestibility of grain amaranth

Amaranth grain is reputed to have a high nutritional value, and as a plant, be tolerant to adverse weather conditions. This suggests that grain amaranth could be useful in tackling malnutrition and the growing burden of cardiometabolic diseases. However, there is insufficient knowledge at present about how the nutrient composition and digestibility of amaranth grain varies with growing environment, crop genotype, and post-harvest processing. We investigated the effect of the source and processing of amaranth grains on the digestibility of protein and lipid present in the grains. There was variation in the composition and digestibility of raw grains from different sources, indicating a role of genotype and/or growing environment which warrants further investigation. The greatest differences in digestibility were measured between the different processing techniques. This indicates that efforts to increase the cultivation and consumption of grain amaranth need to be supported by education about effective processing and preparation techniques

Distribution and phenotypic characteristics of common bean (Phaseolus vulgaris L.) nodulating bacteria in diverse soils

Bacteria were isolated from the root nodules using common bean as a trap host. Growth and morphological characteristics of the bacterial isolates were described on yeast extract mannitol mineral salts agar and broth media. The results showed that over 67% of the isolates produced extracellular polysaccharide with an entire margin and convex elevation. The others differentiated into cream yellow, cream white and milky white colouration with colony area ranging from 0.8 to 26 mm2. The population levels of bacteria nodulating common bean varied in soils and were not affected by the cropping system. However, selected soil parameters greatly influenced the occurrence and distribution of these bacteria. The isolation of indigenous bacteria in all the soils with different cropping systems is an indication that the soils are favourable for nitrogen fixation. Based on the differences in cultural characteristics of the isolates, our data demonstrate the presence of high diversity of bacteria associated with bean nodules

Diversity of endophytic bacteria isolated from leguminous agroforestry trees in western Kenya

Abstract Plants have diverse and vast niches colonized by endophytic microorganisms that promote the wellbeing of host plant. These microbes inhabit internal plant tissues with no signs of ill health. Bacterial endophytes from many plants have been isolated and characterized due to their beneficial roles however their diversity in leguminous plants still remain unexploited. Diversity of bacterial endophytes isolated from Sesbania sesban, Leucaena diversifolia and Calliandra calothyrsus was assessed using morphological and molecular characteristics. A total of 27 pure isolates were recovered from C. Calothyrsus, L. diversifolia and S. sesban constituting 44.4%, 33.3% and 22.2% from the leaves, stems and roots respectively. The isolates differentiated into Gram positive and negative with rods and spherical shapes. Analysis of 16S rRNA gene sequences revealed 8 closely related bacterial genera that consisted of Bacillus (33.3%), Staphylococcus (22.2%), Alcaligens (11.1%), Pantoea (11.1%), Xanthomonas,and Sphingomonas (7.4%) each. Others included Acinetobacter, and Pseudomonas at 3.7% each. Bacterial endophytes of genus bacillus were isolated from all the three plants. These results indicate the presence of high diversity of endophytic bacteria associated with the different parts of L. diversifolia, S. sesban and C. salothyrsus growing in western Kenya

Fungi and Aflatoxin Levels in Traditionally Processed Cassava (Manihot esculenta Crantz) Products in Homa Bay County, Kenya

Cassava (Manihot esculenta Crantz) is a major source of carbohydrates, calcium, vitamins (B and C), and essential minerals and is the third most important source of calories in the tropics. However, it is not clear if the traditional processing methods expose the products to microbial contamination. This study assessed the levels of fungi and aflatoxin contamination in traditionally processed cassava products (Akuoga and Abeta). A total of 38 samples were collected from the local markets in 7 subcounties in Homa Bay County, Kenya. The levels of aflatoxin were determined using an indirect competitive ELISA protocol. Yeast and mould contamination was determined using ISO 21527-2 method. Mean aflatoxin levels in chopped, fermented, and sun-dried cassava (Akuoga) were 0.36 μg/kg compared to 0.25 μg/kg in chopped and sun-dried (Abeta) products. Aflatoxin contamination was detected in 55% of the samples and ranged from 0–5.33 μg/kg. These levels are within 10 μg/kg recommended by the CODEX STAN 193-1995. Yeast and mould counts in fermented and chopped sun-dried products were 3.16 log Cfu/g and 2.92 log Cfu/g, respectively. The yeast and mould counts were above standards set by East African Standard 739:2010 in 62% (Akuoga) and 58% (Abeta). The most prevalent fungal species were Saccharomyces cerevisiae (68.4%) and Candida rugosa (68%) followed by Candida parapsilosis (18.4%), Candida tropicalis (15.8%), Candida humilis (15.8%), and Aspergillus spp. (5.3%). Aspergillus spp. was the only mycotoxigenic mould isolated from the samples. The study shows that cassava consumers are exposed to the risk of aflatoxin poisoning. The study, therefore, recommends appropriate surveillance to ensure safety standards

IMPACT OF LAND USE ON THE DISTRIBUTION AND DIVERSITY OF ENTOMOPATHOGENIC NEMATODES IN EMBU AND TAITA DISTRICTS, KENYA

Natural entomopathogenic nematodes (EPNs) are considered as potential biological control agents against soil-borne insect pests. This study was conducted to determine the impact of land use on the distribution, occurrence and diversity of entomopathogenic nematode community. Isolation of EPNs was done using the baiting technique and application of morphological identification methods revealed presence of the genus Steinernema. Land use intensification negatively affected the occurrence and recovery frequency in soils of Embu and Taita districts. The occurrence of EPNs was high in soils from coffee than maize and beans which had more nematodes than planted forest and napier grass followed by natural forest and tea respectively. PCR-RFLP of the internal transcribed spacer region on the ribosomal(r) DNA of the EPN isolates and digestion of the products by Alu I enzyme showed molecular variations among the isolates. The study has demonstrated that the frequency of occurrence and species variation of EPNs is different in various land uses

Genetic diversity of symbiotic bacteria nodulating common bean (Phaseolus vulgaris) in western Kenya.

Biological nitrogen fixation (BNF) in legumes plays a critical role in improving soil fertility. Despite this vital role, there is limited information on the genetic diversity and BNF of bacteria nodulating common bean (Phaseolus vulgaris L.). This study evaluated the genetic diversity and symbiotic nitrogen fixation of bacteria nodulating common bean in soils of Western Kenya. The genetic diversity was determined using 16S rRNA gene partial sequences while BNF was estimated in a greenhouse experiment. The sequences of the native isolates were closely affiliated with members from the genera Pantoea, Klebsiella, Rhizobium, Enterobacter and Bacillus. These results show that apart from rhizobia, there are non-rhizobial strains in the nodules of common bean. The symbiotic efficiency (SE) of native isolates varied and exhibited comparable or superior BNF compared to the local commercial inoculants (CIAT 899 and Strain 446). Isolates (MMUST 003 [KP027691], MMUST 004 [KP027687], MMUST 005 [KP027688], KSM 001 [KP027682], KSM 002 [KP027680], KSM 003 [KP027683] and KSM 005 [KP027685]) recorded equal or significantly higher SE (p < 0.05) compared to N supplemented treatments. The results demonstrate the presence of genetic diversity of native bacteria nodulating bean that are effective in N fixation. These elite bacterial strains should be exploited as candidates for the development of Phaseolus vulgaris inoculants