Population Levels of Indigenous Bradyrhizobia Nodulating Promiscuous Soybean in two Kenyan Soils of the Semi-arid and Semi-humid Agroecological Zones

Soybeans grown in Africa have been selected to nodulate effectively with indigenous Bradyrhizobium spp. populations since Bradyrhizobium japonicum populations are considered absent or in very low numbers in African soils. The major objective of this study was to estimate total population of Bradyrhizobia specific to soybean in two agro-ecologically different study sites, Kiboko in Makueni District, Southeast Kenya (semi-arid to arid conditions) and Kaguru in Meru District, East Kenya (semi-humid climate) . The population of the indigenous rhizobia specific to soybeans was determined using the Most Probable Number (MPN) plant infection technique. In these experiments, the total Bradyrhizobia populations, the population sizes of taxonomically defined slow-growing Bradyrhizobia specific to soybean and the population sizes of Bradyrhizobia spp. specific to tropical Glycine Cross (TGx) varieties were determined for the two study sites. Cowpea, Vigna unguiculata, cultivar Ken Kunde I was used to estimate the total Bradyrhizobia spp. population. Clark soybean, Glycine max, was used to estimate the population sizes of taxonomically defined slow-growing Bradyrhizobia spp. specific to soybean while a TGx genotype, SB12-TGx1869-31E was used to determine the population sizes of Bradyrhizobia spp. specific to TGx varieties. The results of the MPN counts indicated that the total Bradyrhizobia population in Kiboko was between 2.59x104 and 1.89x105. The population size of taxonomically defined slowgrowing Bradyrhizobia in Kiboko was between 2.59x102 and 1.89x103 cells per gram of soil sample while the approximate Bradyrhizobia population specific to TGx genotype was between 7.81x102 and 5.67x103 cells per gram of soil. In Kaguru, the approximate total Bradyrhizobia population was between 1.04x102 and 7.56x103 cells per gram of soil. The population size of taxonomically defined slow-growing Bradyrhizobia was between 1.33x102 and 9.72x102 cells per gram of soil while the approximate Bradyrhizobia population specific toTGx genotype was between 2.37x102 and 1.73x103 per gram of soil. These populations were adequate to give satisfactory results on nodulation and nitrogen fixation in the two study sites

Detection of trypanosomes in small ruminants and pigs in western Kenya: important reservoirs in the epidemiology of sleeping sickness?

BACKGROUND: Trypanosomosis is a major impediment to livestock farming in sub-Saharan Africa and limits the full potential of agricultural development in the 36 countries where it is endemic. In man, sleeping sickness is fatal if untreated and causes severe morbidity. This study was undertaken in western Kenya, an area that is endemic for both human and livestock trypanosomosis. While trypanosomosis in livestock is present at high levels of endemicity, sleeping sickness occurs at low levels over long periods, interspersed with epidemics, underscoring the complexity of the disease epidemiology. In this study, we sought to investigate the prevalence of trypanosomes in small ruminants and pigs, and the potential of these livestock as reservoirs of potentially human-infective trypanosomes. The study was undertaken in 5 villages, to address two key questions: i) are small ruminants and pigs important in the transmission dynamics of trypanosomosis? and ii), do they harbour potentially human infective trypanosomes? Answers to these questions are important in developing strategies for the control of both livestock and human trypanosomosis. RESULTS: Eighty-six animals, representing 21.3% of the 402 sampled in the 5 villages, were detected as positive by PCR using a panel of primers that identify trypanosomes to the level of the species and sub-species. These were categorised as 23 (5.7%) infections of T. vivax, 22 (5.5%) of T. simiae, 21 (5.2%) of the T. congolense clade and 20 (5.0%) of T. brucei ssp. The sheep was more susceptible to trypanosome infection as compared to goats and pigs. The 20 T. brucei positive samples were evaluated by PCR for the presence of the Serum Resistance Associated (SRA) gene, which has been linked to human infectivity in T. b. rhodesiense. Three samples (one pig, one sheep and one goat) were found to have the SRA gene. These results suggest that sheep, goats and pigs, which are kept alongside cattle, may harbour human-infective trypanosomes. CONCLUSION: We conclude that all livestock kept in this T. b. rhodesiense endemic area acquire natural infections of trypanosomes, and are therefore important in the transmission cycle. Sheep, goats and pigs harbour trypanosomes that are potentially infective to man. Hence, the control of trypanosomosis in these livestock is essential to the success of any strategy to control the disease in man and livestock

A Comparative Study of the Physiochemical and Bacteriological Parameters of Potable Water from Different Sources in Kitui County, Kenya

Developing nations are experiencing an ever-increasing demand for safe water due to climate change and the ever-increasing human population. Various strategies including construction of shallow wells, boreholes and sand dams along the river are done to make water available to various households. However, availability of water sources near are faced with challenges of pollution from a variety of sources. The aim of this study was to determine the levels of selected bacteriological and physico-chemical parameters in three potable water sources namely Kiembeni borehole, Mwitasyano River and Kalundu Dam in Kitui County.  The quality of this water was compared to the standards for potable water prescribed by Kenya Bureau of Standards (KEBS). Representative sampling was conducted during the wet season (October 2019) and the dry season (August 2020) in the three sampling sites. The samples were analyzed for physico-chemical parameters: pH, color, turbidity, alkalinity, conductivity, iron, calcium, magnesium, hardness, chloride, fluoride, sulphates, ammonia, total dissolved solids and bacteriological parameters: total and fecal coliform. The analysis was performed at the Kenya Water Institute (KEWI) laboratory using standard procedures. The values obtained for the different water sources in the wet season and dry season were pooled and mean values calculated to determine the overall quality of drinking water. The results indicated that all the water sources had fecal coliform levels unsuitable for drinking water. Most of the values obtained for pH, color, alkalinity, conductivity, calcium, fluoride and sulphates in all sources of water were within the recommended potable water standards by KEBS. However, turbidity, iron and total coliform obtained values for borehole water samples were not within the recommended KEBS standards. The river and dam water samples were within the recommended standards for magnesium, hardness, chloride, ammonia and total dissolved solids. Although results indicate that some of the physico-chemical parameters were in conformance with the recommended standards, the overall bacteriological parameters render the water unsuitable for drinking.  Thus, public health intervention programmes should be focused on addressing various sources of water pollution including regular disinfection of water. Keywords: Water quality, Physico-chemical, Kitui County, Assessment DOI: 10.7176/JEES/12-11-05 Publication date: November 30th 202

Genetic structure and mating system of wild cowpea populations in West Africa

Abstract Background Cowpea is a highly inbred crop. It is part of a crop-weed complex, whose origin and dynamics is unknown, which is distributed across the African continent. This study examined outcrossing rates and genetic structures in 35 wild cowpea (Vigna unguiculata ssp. unguiculata var. spontanea) populations from West Africa, using 21 isozyme loci, 9 of them showing polymorphism. Results Outcrossing rates ranged from 1% to 9.5% (mean 3.4%), which classifies the wild cowpea breeding system as primarily selfing, though rare outcrossing events were detected in each population studied. Furthermore, the analyses of both the genetic structure of populations and the relationships between the wild and domesticated groups suggest possibilities of gene flow that are corroborated by field observations. Conclusions As expected in a predominantly inbred breeding system, wild cowpea shows high levels of genetic differentiation and low levels of genetic diversity within populations. Gene flow from domesticated to wild cowpea does occur, although the lack of strong genetic swamping and modified seed morphology in the wild populations suggest that these introgressions should be rare.</p