![]() Streptomyces also has a complex developmental cycle that begins with the germination of a spore to form multigenomic substrate mycelia. In addition, the social and multicellular behaviour of this bacterium requires intercellular communication ( Kroos, 2007 Velicer and Vos, 2009b). Fruiting body development and predation of other organisms induce rippling behaviour during which the cells organize themselves in parallel ridges that move coordinately ( Berleman et al., 2006). Development culminates when the rod-shaped vegetative cells differentiate into metabolically quiescent, spherical spores that germinate when nutrients are supplied ( Dworkin, 1996). This social behaviour has been more extensively studied during fruiting body development following nutrition depletion. xanthus S motility, cells glide in groups. Other predators are specialists and only feed a single species ( Velicer and Mendes-Soares, 2009a).ĭuring M. Myxococcus is not a specialized predator, and can feed on a single species including Escherichia coli, Corynebacterium glutamicum, Micrococcus luteus and Saccharomyces cerevisiae ( Hillesland et al., 2007 Berleman and Kirby, 2009). It attacks in groups like a wolf pack by surrounding the prey ( Velicer and Mendes-Soares, 2009a). This myxobacterium preys on a wide variety of microorganisms by secreting lytic enzymes and toxic molecules ( Velicer and Mendes-Soares, 2009a). Myxococcus xanthus has been extensively studied ( Berleman and Kirby, 2009 Velicer and Mendes-Soares, 2009a) and moves on solid surfaces by two surface translocation mechanisms, the adventurous (A motility) and social (S motility) motility systems ( Mauriello and Zusman, 2007). There are several groups of bacterial predators. xanthus cultures until 2005 when the use of high-performance liquid chromatograph mass spectrometry (HPLC-MS) technology provided a sensitive method to identify five antibiotic families ( Wenzel and Muller, 2009). In fact, no antibiotics were identified in M. xanthus DK1622 has revealed the presence of at least 18 clusters of polyketide/non-ribosomal peptide genes, most of which are not expressed under laboratory conditions ( Wenzel and Muller, 2009). ACT and RED are pigmented and their production is easily visualized. However, only four antibiotics have been detected under laboratory conditions, actinorhodin (ACT), undecylprodigiosin (RED) and calcium dependent antibiotic (CDA), synthesized by proteins encoded by the chromosome, and methylenomicin, whose biosynthetic enzymes are encoded by plasmid SCP1. Streptomyces coelicolor contains 23 gene clusters related to secondary metabolite production ( Bentley et al., 2002). Both bacteria have genomes in excess of 8 Mb and are endowed with the capacity to produce many secondary metabolites. In this work we have examined the confrontation between two typical soil inhabitants, immobile Streptomyces coelicolor and the mobile predator Myxococcus xanthus. Perhaps in natural communities unknown signals trigger gene expression, sometimes in other organisms ( Bassler and Losick, 2006). The number of silent or poorly expressed genes under laboratory conditions may be much higher than originally thought ( Schneiker et al., 2007). Laboratory co-cultures sometimes trigger the expression of genes that remain silent in pure cultures ( Yamanaka et al., 2005). The study of these interactions has attracted much interest ( Shank and Kolter, 2009 Straight and Kolter, 2009 Vos and Velicer, 2009). Bacterial populations in natural habitats are complex communities containing many species that exhibit competition and/or collaboration in order to survive with limiting nutritional resources. ![]()
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