Microbial adaptation to a changeable environment: Cell‐cell interactions mediate physiological and genetic differentiation

Rosenzweig, Ravid; Adams, Julian

doi:10.1002/bies.950161005

Cited by 13 publications

(10 citation statements)

References 40 publications

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“…A similar effect in Serratia is believed to play a role in colonization of new niches [47]. Finally, a clonal population may break into different specialized clones evoked by metabolic demands [48,49] or antibiotic pressure [50]. …”

Section: Discussionmentioning

confidence: 99%

Developmental plasticity of bacterial colonies and consortia in germ-free and gnotobiotic settings

et al. 2012

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BackgroundBacteria grown on semi-solid media can build two types of multicellular structures, depending on the circumstances. Bodies (colonies) arise when a single clone is grown axenically (germ-free), whereas multispecies chimeric consortia contain monoclonal microcolonies of participants. Growth of an axenic colony, mutual interactions of colonies, and negotiation of the morphospace in consortial ecosystems are results of intricate regulatory and metabolic networks. Multicellular structures developed by Serratia sp. are characteristically shaped and colored, forming patterns that reflect their growth conditions (in particular medium composition and the presence of other bacteria).ResultsBuilding on our previous work, we developed a model system for studying ontogeny of multicellular bacterial structures formed by five Serratia sp. morphotypes of two species grown in either "germ-free" or "gnotobiotic" settings (i.e. in the presence of bacteria of other conspecific morphotype, other Serratia species, or E. coli). Monoclonal bodies show regular and reproducible macroscopic appearance of the colony, as well as microscopic pattern of its growing margin. Standard development can be modified in a characteristic and reproducible manner in close vicinity of other bacterial structures (or in the presence of their products). Encounters of colonies with neighbors of a different morphotype or species reveal relationships of dominance, cooperation, or submission; multiple interactions can be summarized in "rock – paper – scissors" network of interrelationships. Chimerical (mixed) plantings consisting of two morphotypes usually produced a “consortium” whose structure is consistent with the model derived from interaction patterns observed in colonies.ConclusionsOur results suggest that development of a bacterial colony can be considered analogous to embryogenesis in animals, plants, or fungi: to proceed, early stages require thorough insulation from the rest of the biosphere. Only later, the newly developing body gets connected to the ecological interactions in the biosphere. Mixed “anlagen” cannot accomplish the first, germ-free phase of development; hence, they will result in the consortium of small colonies. To map early development and subsequent interactions with the rest of the biospheric web, simplified gnotobiotic systems described here may turn to be of general use, complementing similar studies on developing multicellular eukaryots under germ-free or gnotobiotic conditions.

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Section: Discussionmentioning

confidence: 99%

Developmental plasticity of bacterial colonies and consortia in germ-free and gnotobiotic settings

et al. 2012

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“…Complex signalling pathways have evolved in many bacterial systems to permit such an adaptation. Microbial adaptation to environment may resemble the physiological and genetic differentiation usually attributed to higher organisms (Rosenzweig and Adams, 1994). Several issues remain to be resolved, in particular the molecular signal recognized by Nm upon contact with target cells.…”

Section: Discussionmentioning

confidence: 99%

Down‐regulation of pili and capsule of Neisseria meningitidis upon contact with epithelial cells is mediated by CrgA regulatory protein

Deghmane¹,

Giorgini²,

Larribe³

et al. 2002

Molecular Microbiology

132

146

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SummaryThe initial attachment of Neisseria meningitidis to the target cell surface appears to be largely pilus dependent in capsulated bacteria. Intimate adhesion subsequently occurs to permit colonization. We recently reported that insertional inactivation of the crgA gene, which encodes a transcriptional regulator belonging to the LysR family, decreased meningococcal adhesion to epithelial cells and abolished intimate adhesion. In this report, we analyse expression of the pilE and sia genes, which are involved in the biosynthesis of pili and capsule respectively, during bacteria-host cell interactions. Western blotting, transcriptional fusion and reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed that the expression of these genes was downregulated during intimate adhesion. DNA-binding assays, footprinting and RT-PCR analysis indicated that this downregulation was directly mediated by the CrgA protein. The pilE and sia promoters were found to have a CrgA binding motif in common. These results strongly suggest that N. meningitidis displays an adaptive response upon cell contact. CrgA may play a central regulatory role in meningococcal adhesion, particularly in switching from initial to intimate adhesion by downregulating the bacterial surface structures that hinder this adhesion.

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“…Much evidence indicates that bacterial adaptation to changes in the environment may be viewed as genetic and physiological differentiation (Rosenzweig and Adams, 1994). Complex signalling pathways have evolved in many bacterial systems to permit such an adaptation.…”

Section: Discussionmentioning

confidence: 99%

The pilA regulatory gene modulates the pilus‐mediated adhesion of Neisseria meningitidis by controlling the transcription of pilC1

Taha

Giorgini

Nassif

1996

Molecular Microbiology

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Adherence to eukaryotic cells is essential in the pathogenesis of Neisseria meningitidis. Pilus-mediated adhesion has been shown to play an essential role in this process. Pilin, the pilus major subunit, and two pilus associated proteins, PilC1 and PilC2, are key components in meningococcal adhesiveness. Phase and/or antigenic variation of these molecules are the only identified means by which N. meningitidis modulates pilus-mediated adhesion. PilA/PilB is a pleiotropic regulatory system first characterized in Neisseria gonorrhoeae where it controls pilin gene transcription. Similar alleles are found in N. meningitidis. To address the role of this regulatory pathway in N. meningitidis, we engineered a meningococcal pilA mutant strain and analysed the consequences of this mutation on pilus-mediated adhesion using epithelial Hec-1-B cells. This mutation resulted in a threefold reduction in adhesiveness. As no change in the amount of pilin nor in pilin gene mRNA was detected, we compared the expression of the pilC genes in both pilA and parental strains. Two transcriptional fusions pilC1-lacZ and pilC2-lacZ were constructed. A threefold reduction in beta-galactosidase activity was observed in the pilA mutant strain harbouring the pilC1-lacZ fusion. No effect of the pilA mutation on beta-galactosidase activity was observed in the strain carrying the pilC2-lacZ fusion. Gel retardation experiments confirmed that the PilA protein binds to the promoter region of pilC1 but not of pilC2. Taken together, these data demonstrate that PilA modulates meningococcal adhesiveness via the transcription of pilC1. Thus, in addition to phase variation, a more co-ordinate and responsive system may allow a fine adaptation of adhesiveness of meningococci to various environmental signals.

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Microbial adaptation to a changeable environment: Cell‐cell interactions mediate physiological and genetic differentiation

Cited by 13 publications

References 40 publications

Developmental plasticity of bacterial colonies and consortia in germ-free and gnotobiotic settings

Developmental plasticity of bacterial colonies and consortia in germ-free and gnotobiotic settings

Down‐regulation of pili and capsule of Neisseria meningitidis upon contact with epithelial cells is mediated by CrgA regulatory protein

The pilA regulatory gene modulates the pilus‐mediated adhesion of Neisseria meningitidis by controlling the transcription of pilC1

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