Microbial Diversity III Summary

Microbial Diversity Overview

  • Focus on microbial diversity in marine biology.

Haeckel's Tree of Life

  • Historical perspective from Haeckel (1866) and Banfield et al. (2016).

Endosymbiosis

  • Primary, secondary, and tertiary endosymbiosis processes highlighted, focusing on various algal and bacterial groups.
    • Tertiary Endosymbiosis: Key groups (e.g., diatoms, haptophytes).
    • Synapomorphies: Different groups like SAR, Chromalveolates, and Archaeplastida.

Bacterial Diversity

  • Current classification based on the Bacteriological Code.
  • Major Divisions: 92 phyla, often uncultured and identified via environmental DNA.
  • Classification remains dynamic.

Bacterial Species Concept

  • Define bacterial species through DNA-DNA hybridization and 16S rRNA similarity.

Heterotrophic Strategies in Ocean Bacteria

  • Oligotrophs: Adapted to low nutrients, slow-growing.
  • Copiotrophs: Rapid growth in nutrient-rich conditions.

Roseobacter Clade

  • Significant component of ocean bacterioplankton, plays role in biogeochemical cycles.

SAR11 - Pelagibacter ubique

  • Most abundant in ocean, tiny and dominates surface communities.

Cyanobacteria

  • Key role in CO2 fixation and O2 production.
    • Synechococcus & Prochlorococcus: Major contributors in surface waters.

Sulfur-Oxidizing Bacteria (SOB)

  • Metabolism involves reduced sulfur compounds; important in microbial mats and hydrothermal vents.
  • Some are anaerobic and use nitrate as an electron acceptor.

Hydrothermal Vents & Symbiosis

  • Invertebrates like tube worms contain symbiotic bacteria, vital for nutrition.

Vibrio Family

  • Commonly found in marine environments; include important pathogens and bioluminescent species.

Oil-Degrading Marine Bacteria

  • Obligate Hydrocarbonoclastic Bacteria (OHCB): Key players in degrading oil, e.g., Alcanivorax.

Deepwater Horizon Oil Spill

  • Largest accidental marine oil spill; significant impact and bacterial response documented.

Importance of Methanogens

  • Methane production in sediments, significant greenhouse gas implications.

Conclusion

  • The study of microbial diversity encompasses complex interactions and crucial ecological roles in marine environments.