Thinking About Bacterial Populations as Multicellular Organisms

Abstract

It has been a decade since multicellularity was proposed as a general bacterial trait. Intercellular communication and multicellular coordination are now known to be widespread among prokaryotes and to affect multiple phenotypes. Many different classes of signaling molecules have been identified in both Gram-positive and Gram-negative species. Bacteria have sophisticated signal transduction networks for integrating intercellular signals with other information to make decisions about gene expression and cellular differentiation. Coordinated multicellular behavior can be observed in a variety of situations, including development of E. coli and B. subtilis colonies, swarming by Proteus and Serratia, and spatially organized interspecific metabolic cooperation in anaerobic bioreactor granules. Bacteria benefit from multicellular cooperation by using cellular division of labor, accessing resources that cannot effectively be utilized by single cells, collectively defending against antagonists, and optimizing population survival by differentiating into distinct cell types.

Molecular eco-systems biology: towards an understanding of community function

“…Given this complexity of cellular interactions, which are analogous to those of multicellular organisms [36], the reconstruction of ecosystem-wide molecular networks will be far from trivial. However, as more relevant data have become available, some aspects of cooperative molecular networks can already be derived.…”

“…As many of these processes are also linked to the abundance of organisms (for example, quorum sensing [33]) the nature and presence of these molecular interactions are highly dependent on population structure, which might vary over time (discussed in the next section). In addition, in many environments, the physical and MDC Repository | http://edoc.mdc-berlin.de/9603/ 2 Raes J and Bork P geographical heterogeneity of the local habitat can determine the interactions that are possible [35].Given this complexity of cellular interactions, which are analogous to those of multicellular organisms [36], the reconstruction of ecosystem-wide molecular networks will be far from trivial. However, as more relevant data have become available, some aspects of cooperative molecular networks can already be derived.…”

Bacteria are small but not stupid: cognition, natural genetic engineering and socio-bacteriology

“…The nature of chemically characterized signaling molecules ranges from oligopeptides, proteins, amino acids, liposaccharides and fatty acids to aminoglycosides, acyl homoserine lactones and furanosyl borate diester. These chemically diverse signals affect properties as different as antibiotic production, exoenzyme synthesis, bioluminescence, symbiotic root nodulation, virulence, and group motility in addition to competence and sporulation (Shapiro, 1998;Waters & Bassler, 2005). There is, therefore, a rich chemical vocabulary that bacteria use to control numerous multicellular traits.…”

Deadly competition between sibling bacterial colonies

“…When exposed to harsh environmental conditions such as starvation, hard surfaces, extreme heat, and hazardous chemicals, the bacteria can collectively develop sophisticated strategies for adaptation and survival. One aspect of this cooperative behavior is the formation of complex colonies with different spatiotemporal patterns, as needed for efficient response to the environmental conditions (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13).…”