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BIODEEP-WP4

University of Essex. BIODEEP-WP4. Determination of the distribution, taxonomy and diversity of micro-organisms from DHABs, and isolation of strains with biotechnological potential. BIODEEP-WP5.

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BIODEEP-WP4

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  1. University of Essex BIODEEP-WP4 Determination of the distribution, taxonomy and diversity of micro-organisms from DHABs, and isolation of strains with biotechnological potential BIODEEP-WP5 Understanding of ecological relations between the microbial communities and the functioning of DHAB environments Andrea Sass , Terry McGenity

  2. University of Essex Objectives: 1. Isolation of bacteria from different physiological groups • Alterations: • Salt concentration • Oxygen regime • Organic substrate, electron acceptors (“food”) Halophilic, halotolerant, marine organisms Aerobic and anaerobic Degraders of different classes of organic compounds 2. Characterization of isolates 3. Evaluation of the relevance of obtained isolates in situ

  3. University of Essex Major properties of media

  4. University of Essex Isolation under oxic conditions • DNA extraction • Amplificatioon of 16S rRNAgene • RFLP • Sequencing • t-RFLP Isolates Physiological characterization of representative strains

  5. University of Essex total 39 36 25 14 0 0 0 Number of isolates on agar plates

  6. University of Essex Preliminary results from partial sequencing of eight isolates

  7. University of Essex Physiological properties of aerobic strains • The appearance of isolates from the sediments is different from those of the interface: • most of the strains from sediment samples were spore-forming (probably Bacillus-related) • only a few strains of the Bannock interface were spore-forming • Strains further characterized (Bacillus-like bacteria from l’Atalante and Bannock basin) • were capable facultatively anaerobic growth on artificial seawater with fermentable substrates • could grow in liquid media to salt concentrations of up to 15%

  8. University of Essex Relevance of aerobic isolates for the DHAB microbial community • Isolates from sediments possibly derived from resting cells • Isolates from interfaces possibly marine bacteria derived from the oxic water column Isolated organisms unlikely to be very active in situ

  9. University of Essex Future work: Further attempts to isolate extremely halophilic aerobic microorganisms: To obtain Halobacteria or other true aerobic halophiles the media constituents (buffer, major salts, organic compounds) and growth conditions (pH, temperature) can be altered • Further treatment of isolates already obtained: • Screening by RFLP fingerprinting • Partial sequencing of isolates representative of a fingerprint • Physiological characterization of isolates only remotely related to known organisms

  10. University of Essex Anoxic enrichments Media for on board inoculation Subsample for t-RFLP analysis Direct amendment of brine and interface samples Positive enrichments • Further cultivation • Isolation by deep-agar dilution series • Partial sequencing • Physiological characterization of representative strains Media inoculated in the lab

  11. University of Essex total 9 11 0 11 5 1 4 4 Number of positive enrichments cultures (with respect to salt regime and sample)

  12. University of Essex Number of positive enrichments cultures (with respect to organic substrate)

  13. University of Essex Physiological properties of anerobic cultures • Positive enrichments predominantly on high-salt media and on substrates that can be fermented • Most cultures grow relatively fast on media with a high salt concentration

  14. University of Essex Relevance of anaerobic cultures for the DHAB microbial community Enrichments grow readily under conditions similar to those in the DHAB Possibly active in the DHAB

  15. University of Essex Future work: • Further isolation attempts: • for SRB • enrichment experiments with brines concentrated through filtration • Further treatment of enrichments already obtained: • complete isolation procedure • partial sequencing of 16S rRNA gene • physiological characterization of representative phylotypes

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