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Vitamin B12-mediated restoration of defective anaerobic growth leads to reduced biofilm formation in Pseudomonas aeruginosa.

ABSTRACT: Pseudomonas aeruginosa undergoes cell elongation and forms robust biofilms during anaerobic respiratory growth using nitrate (NO(3)(-)) as an alternative electron acceptor. Understanding the mechanism of cell shape change induced upon anaerobiosis is crucial to the development of effective treatments against P. aeruginosa biofilm infection. Here, we uncovered the molecular basis of anaerobiosis-triggered cell elongation and identified vitamin B(12) to be a molecule that can reinstate defective anaerobic growth of P. aeruginosa. The ratio of total cellular DNA content to protein content was significantly decreased in the PAO1 strain grown under anaerobic conditions, indicating that DNA replication is impaired during anaerobic growth. Anaerobic growth of PAO1 reached a higher cell density in the presence of vitamin B(12), an essential coenzyme of class II ribonucleotide reductase. In addition, cell morphology returned to a normal rod shape and transcription of stress-response genes was downregulated under the same anaerobic growth conditions. These results suggest that vitamin B(12), the production of which was suppressed during anaerobic growth, can restore cellular machineries for DNA replication and therefore facilitate better anaerobic growth of P. aeruginosa with normal cell division. Importantly, biofilm formation was substantially decreased when grown with vitamin B(12), further demonstrating that anaerobiosis-induced cell elongation is responsible for robust biofilm formation. Taken together, our data reveal mechanistic details of a morphological change that naturally occurs during anaerobic growth of P. aeruginosa and illustrates the ability of vitamin B(12) to modulate the biofilm-forming capacity of P. aeruginosa under such condition.

SUBMITTER: Lee KM

PROVIDER: S-EPMC3347431 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature

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Vitamin B12-mediated restoration of defective anaerobic growth leads to reduced biofilm formation in Pseudomonas aeruginosa.

Lee Kang-Mu KM Go Junhyeok J Yoon Mi Young MY Park Yongjin Y Kim Sang Cheol SC Yong Dong Eun DE Yoon Sang Sun SS

Infection and immunity 20120227 5

Pseudomonas aeruginosa undergoes cell elongation and forms robust biofilms during anaerobic respiratory growth using nitrate (NO(3)(-)) as an alternative electron acceptor. Understanding the mechanism of cell shape change induced upon anaerobiosis is crucial to the development of effective treatments against P. aeruginosa biofilm infection. Here, we uncovered the molecular basis of anaerobiosis-triggered cell elongation and identified vitamin B(12) to be a molecule that can reinstate defective a ...[more]

PMID: 22371376

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Project description:The survival of bacteria in nature is greatly enhanced by their ability to grow within surface-associated communities called biofilms. Commonly, biofilms generate proliferations of bacterial cells, called microcolonies, which are highly recalcitrant, 3-dimensional foci of bacterial growth. Microcolony growth is initiated by only a subpopulation of bacteria within biofilms, but processes responsible for this differentiation remain poorly understood. Under conditions of crowding and intense competition between bacteria within biofilms, microevolutionary processes such as mutation selection may be important for growth; however their influence on microcolony-based biofilm growth and architecture have not previously been explored. To study mutation in-situ within biofilms, we transformed Pseudomonas aeruginosa cells with a green fluorescent protein gene containing a +1 frameshift mutation. Transformed P. aeruginosa cells were non-fluorescent until a mutation causing reversion to the wildtype sequence occurs. Fluorescence-inducing mutations were observed in microcolony structures, but not in other biofilm cells, or in planktonic cultures of P. aeruginosa cells. Thus microcolonies may represent important foci for mutation and evolution within biofilms. We calculated that microcolony-specific increases in mutation frequency were at least 100-fold compared with planktonically grown cultures. We also observed that mutator phenotypes can enhance microcolony-based growth of P. aeruginosa cells. For P. aeruginosa strains defective in DNA fidelity and error repair, we found that microcolony initiation and growth was enhanced with increased mutation frequency of the organism. We suggest that microcolony-based growth can involve mutation and subsequent selection of mutants better adapted to grow on surfaces within crowded-cell environments. This model for biofilm growth is analogous to mutation selection that occurs during neoplastic progression and tumor development, and may help to explain why structural and genetic heterogeneity are characteristic features of bacterial biofilm populations.

Dataset Information

Vitamin B12-mediated restoration of defective anaerobic growth leads to reduced biofilm formation in Pseudomonas aeruginosa.

Publications

Vitamin B12-mediated restoration of defective anaerobic growth leads to reduced biofilm formation in Pseudomonas aeruginosa.

Similar Datasets

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