Untangling the Distribution of Encephalartos villosus in Nutrient Deficient Soils of South Africa

Information on how bacteria in plants and soil, along with extracellular enzymes, affect nutrient cycling in Encephalartos villosus growing in nutrient-poor and acidic scarp forests is lacking. Bacteria in coralloid roots, rhizosphere, and non-rhizosphere soils were isolated to determine the potential role of soil bacterial communities and their associated enzyme activities in nutrient contributions in rhizosphere and non-rhizosphere soils. The role of soil characteristics and associated bacteria on E. villosus nutrition and nitrogen source reliance was investigated. Encephalartos villosus leaves, coralloid roots, rhizosphere, and non-rhizosphere soils were collected at two scarp forests. Leaf nutrition, nitrogen source reliance, soil nutrition and extracellular enzyme activities were assayed. A phylogenetic approach was used to determine the evolutionary relationship between identified bacterial nucleotide sequences. Twenty, twelve and seven different bacterial genera were isolated from rhizosphere, non-rhizosphere, and coralloid roots, respectively. Phosphorus and nitrogen cycling enzyme activities in E. villosus rhizosphere and non-rhizosphere soils were insignificant. More than 70% of the leaf nitrogen was derived from the atmosphere. This study revealed that plant-associated bacteria with plant growth-promoting functions, soil bacteria, and associated extracellular enzymes play a role in E. villosus nutrition and nitrogen source reliance and contribute to E. villosus rhizosphere and non-rhizosphere soil nutrition.