January JAMS got the new year off to a good start with a solid turnout and some stimulating talks. First up was Olivier Laczka who took us in to the technical realm of biosensors. Olivier’s work has focused on developing cost-effective tools for the rapid identification of micro-organisms relevant to industry and has led to several Patents.
Changes in soil microbial community precede changes in plant community along a chronosequence
Shrubs in semiarid ecosystems facilitate the establishment of other plant species under their canopies and promote changes in these understory plant communities as they grow. To better understand whether plant community dynamics are linked to changes in soil microbes, we characterized soil microbial communities in gaps (interspaces) and under Retama sphaerocarpa shrubs of three different size/age classes. Different methodological approaches including pyrosequencing of 16S rDNA, phospholipid-fatty acid (PLFA) analysis and microbial activity indicators were combined to characterize both the structure and function of microbial communities along the chronosequence. Small shrubs induced an increase in soil bacterial and fungal biomass, a stimulation of microbial activity and changes in the relative abundance of several bacterial groups, preceding aboveground increase in plant richness and biomass. Shrubs promoted a significant increase of Bacteroidetes, Betaproteobacteria and Gammaproteobacteria abundance in detriment of Actinobacteria and Firmicutes without changes in overall bacterial diversity. Some changes in the microbial community increased with shrub age while other did not, being microbial communities in gaps and under the canopy of large shrubs the most differentiated. We argue that the observed changes in composition and function of soil microbial communities may promote the increase in plant growth and understory species richness along the chronosequence. This emphasizes the importance of plant-soil interactions on defining the structure and composition of both plant and soil microbial communities and their impact on ecosystem functioning.