Bacterial population of Rhizospheres and non-Rhizospheres of the mangrove species Rhizophora mucronata from 0 to 10 cm deep

Abstract

The interaction of plants and microorganisms in the rhizospheres and non-rhizospheres of plants is well studied and mastered in the terrestrial environment. In general, given the rhizosphere effect exclusively defining the effectiveness of root exudates to promote multiplication, development and microbial growth in the rhizosphere zones, studies unanimously tend to report that the microbial biomass is rather high in the rhizosphere than in the non-rhizosphere. However, the trend may change in the marine environment. This study was conducted in both the rhizosphere and non-rhizosphere of the mangrove species Rhizophora mucronata at different depths ranging from 0-10 cm, to assess the bacterial community in the rhizosphere and non-rhizosphere and to also address the profile of bacterial community changes. The result showed no difference regarding the bacterial abundance in the rhizosphere and in the non-rhizosphere. However, the abundance of bacteria at 0-5 cm depth was significantly higher in rhizosphere and non-rhizosphere. This could be attributed to the large amount of nutrients available in the surface layer. The unequal distribution of nutrients in the rhizosphere and non-rhizosphere of the mangrove species Rhizophora mucronata could be the consequences of mineralization, immobilization of nutrients in the soil and especially root exudation. The general results of this study can be summarized by showing that if the abundance of bacteria in the rhizosphere zones of terrestrial plants is often high, the trend may be different in aquatic plants, more particularly mangroves, which constitute a separate ecosystem.