Cruentarens are a group of macrolides secreted by the myxobacteria "Byssovorax cruenta". Swarming also describes groupings of some kinds of predatory bacteria such as myxobacteria. In the 1970s he worked on the developmental biology of swarms of myxobacteria. "Sorangium" produces 50% of all known metabolites produced by myxobacteria. Examples include fruiting body formation by "Myxobacteria" and aerial hyphae formation by "Streptomyces", or budding. Sorangium cellulosum is a soil-dwelling Gram-negative bacterium of the group myxobacteria. The second largest is another myxobacteria "Sorangium cellulosum". Spectacular examples of multicellular behavior can be found among the myxobacteria. Others, such as myxobacteria, have multicellular stages in their life cycles. Examples are colonies or swarms of myxobacteria, quorum sensing, and biofilms. DGD is reported in thermophilic bacteria, a few mesophilic bacteria and aggregating myxobacteria. Myxobacteria travel in "swarms" containing many cells kept together by intercellular molecular signals. In response to starvation, myxobacteria develop species-specific multicellular fruiting bodies. Myxobacteria are included among the delta group of proteobacteria, a large taxon of Gram-negative forms.