Comparative description of land use and characteristics of belowground biodiversity benchmark sites in Kenya = Descripción comparativa de usos del suelo y características de la diversidad del subsuelo en sitios empleados como referencia en Kenia

In Kenya, the below-ground biodiversity (BGBD) project selected two benchmark sites for the inventory of soil biota; these included the Irangi and Ngangao forest sites in the Mount Kenya region of Embu District and the Taita Hills area of Taita Taveta District. The areas selected by the project were located in biodiversity hotspots that are supporting rare and endemic plant and animal species. For more in-depth studies and analysis, the broader Embu and Taita benchmark areas were further sub-sampled into smaller areas that we refer to as study areas, designated by the symbols E1 and E2 for Embu and T1 and T2 for Taita benchmark. Within the study areas, we plotted and sampled 200x200 square grids for collecting soil as well as socio-economic data. Site characterization was carried out using the method provided by FAO-UNESCO for characterizing and classifying soils. Further to this, attempts were made to establish land use intensity (LUI) and land productivity (PI) indices that provided land condition indicators. The indicators offered insights into the quantitative relationship between the environmental conditions and land use. Parameters used in the computation of the land use intensity were; total quantity of inputs per ha, the frequency of input application, cropping intensity and cultivation frequency. The soils in Taita Taveta benchmark site were classified as Plinthic Lixisols, Plinthic Acrisols, Dystric Cambisols and Chromic Luvisols, while those from Embu ones were Rhodic Nitisols, Humic Nitisols, Humic Acrisols, Haplic Acrisols and Umbric Andosols. The highest level of soil organic carbon recorded was 7.6% in the forest and the lowest value of 1.6% in intensely cultivated maize-based and horticultural systems. Low land use intensity gradients were observed in the forests (LUI40%). The productivity index (PI) followed a similar trend, being highest in the natural forest and grassland (40-50%) and lowest in horticultural and maize-based systems (15-20%) It was concluded that the decline in soil quality and productivity was linked to increased land use intensification and lack of knowledge of the appropriate management practices for sustainable ecosystem functions and services

Influence of soil chemical and physical properties on occurrence of Trichoderma spp. in Embu, Kenya = Influencia de las propiedades químicas y físicas del suelo sobre la ocurrencia de Trichoderma spp. en Embu, Kenia

Soil samples were collected from 8 land use types in Embu to study the effects of land use on soil chemical and physical parameters and on the occurrence of Trichoderma spp. The fungus was recovered from the soil using the dilution plate and soil washing technique. The remaining soil samples were used to measure the following characters of the soil; pH was determined in 1:1 (w/v) soil – water suspension with pH meter, total nitrogen was determined by the Kjeldahl method, available nutrients P, K, Na, Ca and Mg were determined using Mehlich method while total organic carbon was determined by calorimetric method. Land use type (LUT), plant cover, and soil physical and chemical properties influenced Trichoderma occurrence. The frequency of isolation of Trichoderma spp. was highest in napier LUT followed by indigenous forests. Carbon, N, Mg and Fe loaded with forest land use type suggesting their influence on fungal diversity in this LUT. The forests had clay loam soils with higher porosity and water retention capacity compared with the cultivated LUTs which were characterized with clay soils and bulk density. Napier together with other cultivated LUTs which had low records of the fungus loaded positively with Mn and Cu. This implied that plant type was the major determining factor for the high population of Trichoderma recorded in napier LUT. The diversity of soil factors observed in the fallow lands explained the influence of land management on soil physical and chemical characteristics which in turn determined the fungal distribution. Soil depth (0-20cm) did not influence soil factors though fungal diversity, abundance and evenness varied with depth suggesting the influence of other drivers.This study explains the fact that many factors interact in determining the occurrence of Trichoderma spp. and that in some situations it is the soil that is the key factor determining fungal occurrence and diversity while in others it is the plant type

Land use systems and distribution of Trichoderma species in Embu region, Kenya = Relación entre uso del suelo y la distribución de Trichoderma en la región de Embu, Kenia

The distribution of Trichoderma species in soils of Embu region in relation to land use practices was investigated. The study area was chosen because of its significant land use intensification. Soil washing and dilution plate techniques were used to recover Trichoderma spp from soil samples. The fungal isolates were identified and assigned to eight species. Greater populations as well as a wider range of species were obtained in soils collected from the natural forests while coffee farms were the poorest ones. Land use affected the distribution of Trichoderma. Napier farms had the highest abundance of this fungus. The species that showed the highest incidence in all cases was T. harzianum. Plant type was a major determinant of the occurrence of this fungus. Trichoderma favored plants with shallow and widespread rooting systems, to the deeply rooted perennial coffee and tea trees. The age of the plants also was a driving factor. Both inorganic and organic fertilizers are used in the region. There was a negative correlation between amount of chemical fertilizers and abundance of the fungus. Organic fertilizers were used exclusively in napier farms that had the highest fungal abundance. Soil pH and amount of phosphorus were limiting and influenced the occurrence and abundance of this fungus. However carbon and nitrogen were not limiting though they were high in the forests and napier farms where the fungus was also abundant. Trichoderma showed tolerance to soil acidity since it was abundant in the most acidic soils under napier. Land intensification affected Trichoderma distribution negatively

Staphylococcus epidermidis in the human skin microbiome mediates fermentation to inhibit the growth of Propionibacterium acnes: implications of probiotics in acne vulgaris

Increasing evidence demonstrates that commensal microorganisms in the human skin microbiome help fight pathogens and maintain homeostasis of the microbiome. However, it is unclear how these microorganisms maintain biological balance when one of them overgrows. The overgrowth of Propionibacterium acnes (P. acnes), a commensal skin bacterium, has been associated with the progression of acne vulgaris. Our results demonstrate that skin microorganisms can mediate fermentation of glycerol, which is naturally produced in skin, to enhance their inhibitory effects on P. acnes growth. The skin microorganisms, most of which have been identified as Staphylococcus epidermidis (S. epidermidis), in the microbiome of human fingerprints can ferment glycerol and create inhibition zones to repel a colony of overgrown P. acnes. Succinic acid, one of four short-chain fatty acids (SCFAs) detected in fermented media by nuclear magnetic resonance (NMR) analysis, effectively inhibits the growth of P. acnes in vitro and in vivo. Both intralesional injection and topical application of succinic acid to P. acnes-induced lesions markedly suppress the P. acnes-induced inflammation in mice. We demonstrate for the first time that bacterial members in the skin microbiome can undergo fermentation to rein in the overgrowth of P. acnes. The concept of bacterial interference between P. acnes and S. epidermidis via fermentation can be applied to develop probiotics against acne vulgaris and other skin diseases. In addition, it will open up an entirely new area of study for the biological function of the skin microbiome in promoting human health