Home composting has been strongly advocated in the UK, Europe and North America to divert organic waste away from conventional waste processing. Despite this, little attention has been given to microbial communities and their diversity in these systems. In this study, we examined the diversity of fungal species in 10 different domestic composts by 454 tag-encoded pyrosequencing. We report the recovery of 478 different molecular operational taxonomic units (MOTUs) from the 10 composts with a mean of 176.7 ± 19.6 MOTUs per compost and a mean of 12.9 ± 3.8 unique MOTUs per sample. Microascales (17.21 %), Hypocreales (16.76 %), Sordariales (14.89 %), Eurotiales (11.25 %) and Mortierellales (7.38 %) were the dominant orders in the community, with Pseudallescheria (9.52 %), Penicillium (8.43 %), Mortierella (3.60 %) and Fusarium (3.31 %) being the most abundant genera. Fungal communities in home composts were substantially different to large-scale commercial composts, with thermophilic and thermotolerant fungi present in much lower numbers. Significantly, 46.2 % of all sequences were identified as uncultured fungi or could not be assigned above the family level, suggesting there are a high number of new genera and species in these environments still to be described.
Ixotrophy is a process that enables certain microbes to prey on other cells. The ability of cells to aggregate or adhere is thought to be a significant initial step in ixotrophy. The gliding, multicellular filamentous bacterium Aureispira sp. CCB-QB1 belongs to the family Saprospiraceae and preys on bacteria such as Vibrio sp. in seawater. Adhesion and cell aggregation were coincident with preying and were hypothesized to play an important role in the ixotrophy in this bacterium. To test this hypothesis, experiments to elucidate the mechanisms of aggregation or adhesion in this bacterium were performed. The ability of Aureispira QB1 to adhere and aggregate to prey bacterium, Vibrio sp., required divalent cations, especially calcium ions. In the presence of calcium, Aureispira QB1 cells captured 99 % of Vibrio sp. cells after 60 min of incubation. Toluidine blue O, which binds acidic polysaccharides, bound to Aureispira QB1 and inhibited adhesion of Aureispira QB1. These results suggest that acidic polysaccharides are needed for aggregation or adhesion of Aureispira and that calcium ions play a significant role in these phenomena.