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Koh KS, Lam KW, Alhede M, Queck SY, Labbate M, Kjelleberg S, Rice SA. Phenotypic diversification and adaptation of Serratia marcescens MG1 biofilm-derived morphotypes. J Bacteriol 2006; 189:119-30. [PMID: 17071749 PMCID: PMC1797207 DOI: 10.1128/jb.00930-06] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We report here the characterization of dispersal variants from microcolony-type biofilms of Serratia marcescens MG1. Biofilm formation proceeds through a reproducible process of attachment, aggregation, microcolony development, hollow colony formation, and dispersal. From the time when hollow colonies were observed in flow cell biofilms after 3 to 4 days, at least six different morphological colony variants were consistently isolated from the biofilm effluent. The timing and pattern of variant formation were found to follow a predictable sequence, where some variants, such as a smooth variant with a sticky colony texture (SSV), could be consistently isolated at the time when mature hollow colonies were observed, whereas a variant that produced copious amounts of capsular polysaccharide (SUMV) was always isolated at late stages of biofilm development and coincided with cell death and biofilm dispersal or sloughing. The morphological variants differed extensively from the wild type in attachment, biofilm formation, and cell ultrastructure properties. For example, SSV formed two- to threefold more biofilm biomass than the wild type in batch biofilm assays, despite having a similar growth rate and attachment capacity. Interestingly, the SUMV, and no other variants, was readily isolated from an established SSV biofilm, indicating that the SUMV is a second-generation genetic variant derived from SSV. Planktonic cultures showed significantly lower frequencies of variant formation than the biofilms (5.05 x 10(-8) versus 4.83 x 10(-6), respectively), suggesting that there is strong, diversifying selection occurring within biofilms and that biofilm dispersal involves phenotypic radiation with divergent phenotypes.
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Affiliation(s)
- Kai Shyang Koh
- The Centre for Marine Biofouling and Bio-Innovation, The University of New South Wales, Sydney, NSW 2052, Australia, The School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia, Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Kin Wai Lam
- The Centre for Marine Biofouling and Bio-Innovation, The University of New South Wales, Sydney, NSW 2052, Australia, The School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia, Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Morten Alhede
- The Centre for Marine Biofouling and Bio-Innovation, The University of New South Wales, Sydney, NSW 2052, Australia, The School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia, Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Shu Yeong Queck
- The Centre for Marine Biofouling and Bio-Innovation, The University of New South Wales, Sydney, NSW 2052, Australia, The School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia, Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Maurizio Labbate
- The Centre for Marine Biofouling and Bio-Innovation, The University of New South Wales, Sydney, NSW 2052, Australia, The School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia, Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
| | - Staffan Kjelleberg
- The Centre for Marine Biofouling and Bio-Innovation, The University of New South Wales, Sydney, NSW 2052, Australia, The School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia, Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
- Corresponding author. Mailing address: The School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia. Phone: 61-2-9385-2102. Fax: 61-2-9385-1779. E-mail:
| | - Scott A. Rice
- The Centre for Marine Biofouling and Bio-Innovation, The University of New South Wales, Sydney, NSW 2052, Australia, The School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW 2052, Australia, Center for Biomedical Microbiology, BioCentrum-DTU, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
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Gonzalez G. Habitable zones in the universe. ORIGINS LIFE EVOL B 2005; 35:555-606. [PMID: 16254692 DOI: 10.1007/s11084-005-5010-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2004] [Accepted: 03/15/2005] [Indexed: 10/25/2022]
Abstract
Habitability varies dramatically with location and time in the universe. This was recognized centuries ago, but it was only in the last few decades that astronomers began to systematize the study of habitability. The introduction of the concept of the habitable zone was key to progress in this area. The habitable zone concept was first applied to the space around a star, now called the Circumstellar Habitable Zone. Recently, other, vastly broader, habitable zones have been proposed. We review the historical development of the concept of habitable zones and the present state of the research. We also suggest ways to make progress on each of the habitable zones and to unify them into a single concept encompassing the entire universe.
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Affiliation(s)
- Guillermo Gonzalez
- Department of Physics and Astronomy, Iowa State University, Ames, Iowa, 50011, USA.
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Schwabe C. Genomic potential hypothesis of evolution: a concept of biogenesis in habitable spaces of the universe. THE ANATOMICAL RECORD 2002; 268:171-9. [PMID: 12382315 DOI: 10.1002/ar.10151] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The new hypothesis of evolution establishes a contiguity of life sciences with cosmology, physics, and chemistry, and provides a basis for the search for life on other planets. Chemistry is the sole driving force of the assembly of life, under the subtle guidance exerted by bonding orbital geometry. That phenomenon leads to multiple origins that function on the same principles but are different to the extent that their nucleic acid core varies. Thus, thoughts about the origins of life and the development of complexity have been transferred from the chance orientation of the past to the realm of atomic structures, which are subject to the laws of thermodynamics and kinetics. Evolution is a legitimate subject of basic science, and the complexity of life will submit to the laws of chemistry and physics as the problem is viewed from a new perspective. The paradigm connects life to the big events that formed every sphere of our living space and that keeps conditions fine-tuned for life to persist, perhaps a billion years or more. The "genomic potential" hypothesis leads to the prediction that life like ours is likely to exist in galaxies that are as distant from the origin of the universe as the Milky Way, and that the habitable zone of our galaxy harbors other living planets as well.
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Affiliation(s)
- Christian Schwabe
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston 29425, USA.
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