Bacterial Circadian Programs

Johnson, Carl Hirschie

doi:10.1101/sqb.2007.72.027

Cited by 13 publications

(7 citation statements)

References 73 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Some strategies, such as circadian rhythms, require explicit molecular clocks for proper execution (1, 2), but clocks may also be present in nonphotosynthetic prokaryotes (3, 4). Bacteria can also exhibit anticipatory control (5), in which they respond to external cues, such as changes in temperature and oxygen concentration (6), to predict and adapt to environmental change before it occurs.…”

Section: Introductionmentioning

confidence: 99%

Microbial Communities Are Well Adapted to Disturbances in Energy Input

2016

View full text Add to dashboard Cite

Within the broader ecological context, biological communities are often viewed as stable and as only experiencing succession or replacement when subject to external perturbations, such as changes in food availability or the introduction of exotic species. Our findings indicate that microbial communities can exhibit strong internal dynamics that may be more important in shaping community succession than external drivers. Dynamic “unstable” communities may be important for ecosystem functional stability, with rare organisms playing an important role in community restructuring. Understanding the mechanisms responsible for internal community dynamics will certainly be required for understanding and manipulating microbiomes in both host-associated and natural ecosystems.

show abstract

Section: Introductionmentioning

confidence: 99%

Microbial Communities Are Well Adapted to Disturbances in Energy Input

2016

View full text Add to dashboard Cite

show abstract

“…Microorganisms host a diverse repertoire of temporal strategies to maximize their productivity under a variety of environmental settings that undergo periodic as well as aperiodic change. Some strategies, such as circadian rhythms, require explicit molecular clocks for proper execution (1, 2), but clocks may also be present in non-photosynthetic prokaryotes (3, 4). Bacteria can also exhibit anticipatory control (5) in which they respond to external cues, such as changes in temperature and oxygen concentration (6), to predict and adapt to environmental change before it occurs.…”

Section: Introductionmentioning

confidence: 99%

Microbial Communities are Well Adapted to Disturbances in Energy Input

Fernandez‐Gonzalez

Huber

Vallino

2016

Preprint

View full text Add to dashboard Cite

Although microbial systems are well suited for studying concepts in ecological theory, little is known about how microbial communities respond to longterm periodic perturbations beyond diel oscillations. Taking advantage of an ongoing microcosm experiment, we studied how methanotrophic microbial communities adapted to disturbances in energy input over a 20-day cycle period. Sequencing of bacterial 16S rRNA genes together with quantification of microbial abundance and ecosystem function were used to explore the long-term dynamics (510 days) of methanotrophic communities under continuous versus cyclic chemical energy supply. We observed that microbial communities appeared inherently well adapted to disturbances in energy input and that changes in community structure in both treatments were more dependent on internal dynamics than on external forcing. The results also showed that the rare biosphere was critical to seeding the internal community dynamics, perhaps due to cross-feeding or other strategies. We conclude that in our experimental system, internal feedbacks were more important than external drivers in shaping the community dynamics over time, suggesting that ecosystems can maintain their function despite inherently unstable community dynamics. IMPORTANCEWithin the broader ecological context, biological communities are often viewed as stable and as only experiencing succession or replacement when subject to external perturbations, such as changes in food availability or the introduction of exotic species. Our findings indicate that microbial communities can exhibit strong internal dynamics that may be more important in shaping community succession than external drivers. Dynamic "unstable" communities may be important for ecosystem functional stability, with rare organisms playing an important role in community restructuring. Understanding the mechanisms responsible for internal community dynamics will certainly be required for understanding and manipulating microbiomes in both host-associated and natural ecosystems.KEYWORDS: 16S rRNA gene, bacteria, internal community dynamics, microbial community dynamics, chemostat cultures, endogenous drivers, energy input pulse, rare biosphere, structure and function M icroorganisms host a diverse repertoire of temporal strategies to maximize their productivity under a variety of environmental settings that undergo periodic as well as aperiodic change. Some strategies, such as circadian rhythms, require explicit molecular clocks for proper execution (1, 2), but clocks may also be present in nonphotosynthetic prokaryotes (3,4). Bacteria can also exhibit anticipatory control (5), in which they respond to external cues, such as changes in temperature and oxygen concentration (6), to predict and adapt to environmental change before it occurs. Bacteria that anticipate environmental change have an obvious fitness advantage, and anticipatory strategies may stabilize ecosystems against perturbations (7,8). Temporal strategies that do not rely on internal clocks include ...

show abstract

“…Furthermore, possession of a circadian clock has been shown to enhance the adaptive fitness of Cyanobacteria in a wide variety of environmental conditions (Woelfle et al ., ). In prokaryotic organisms, the circadian rhythms have been described only in photosynthetic bacteria (Johnson, ), where they were mainly studied in Cyanobacteria and lately also in the purple bacteria Rhodobacter sphaeroides (Min et al ., 2005a). Although KaiB and KaiC are found in several prokaryotes belonging to different species (Dvornyk et al ., ; Loza‐Correa et al ., ), their implication in circadian clocks has never been shown.…”

Section: Introductionmentioning

confidence: 99%

The Legionella pneumophila kai operon is implicated in stress response and confers fitness in competitive environments

Loza-Correa

Sahr

Rolando

et al. 2013

Environmental Microbiology

View full text Add to dashboard Cite

Summary Legionella pneumophila uses aquatic protozoa as replication niche and protection from harsh environments. Although L. pneumophila is not known to have a circadian clock, it encodes homologues of the KaiBC proteins of Cyanobacteria that regulate circadian gene expression. We show that L. pneumophila kaiB, kaiC and the downstream gene lpp1114, are transcribed as a unit under the control of the stress sigma factor RpoS. KaiC and KaiB of L. pneumophila do not interact as evidenced by yeast and bacterial two-hybrid analyses. Fusion of the C-terminal residues of cyanobacterial KaiB to Legionella KaiB restores their interaction. In contrast, KaiC of L. pneumophila conserved autophosphorylation activity, but KaiB does not trigger the dephosphorylation of KaiC like in Cyanobacteria. The crystal structure of L. pneumophila KaiB suggests that it is an oxidoreductase-like protein with a typical thioredoxin fold. Indeed, mutant analyses revealed that the kai operon-encoded proteins increase fitness of L. pneumophila in competitive environments, and confer higher resistance to oxidative and sodium stress. The phylogenetic analysis indicates that L. pneumophila KaiBC resemble Synechosystis KaiC2B2 and not circadian KaiB1C1. Thus, the L. pneumophila Kai proteins do not encode a circadian clock, but enhance stress resistance and adaption to changes in the environments.

show abstract

Bacterial Circadian Programs

Cited by 13 publications

References 73 publications

Microbial Communities Are Well Adapted to Disturbances in Energy Input

Microbial Communities Are Well Adapted to Disturbances in Energy Input

Microbial Communities are Well Adapted to Disturbances in Energy Input

The Legionella pneumophila kai operon is implicated in stress response and confers fitness in competitive environments

Contact Info

Product

Resources

About