MICRO ORGANISMS

Micro organisms

Micro organisms

Experiment 1: Demonstrate the Widespread Occurrence of Micro organisms in the Environment

Question 1

In the last decades, substantial changes have occurred regarding what scientists consider the limits of habitable environmental conditions. Our knowledge about extreme environments and the limits of life on Earth has been greatly expanded. These advances have been fundamental to the development of astrobiology, which studies the origin, evolution, and distribution of life in the universe.

The intense efforts in search of living systems in harsh environments on Earth have given us important clues about the origins of life on Earth. Hydrothermal environments are considered the most proper locals where life may have originated, since these environments provide energy, carbon sources, electron acceptors, and a variety of inorganic surfaces suitable for the formation of biopolymers. For this reason, hydrothermal environments should also be considered the targets for the origins of life in other planets within the Solar System and beyond (Horikoshi, 1998, pp. 56).

Studies in extreme ambient conditions have changed the previous paradigm that life can only be found on pleasant Earth-like planets. The continuous discovery of living systems thriving in habitats previously thought to be uninhabited has inspired us to speculate more realistically on the forms and constraints that extraterrestrial life may take on other planets. Nowadays, numerous planetary bodies in our Solar System have been suggested to sustain life.

Furthermore, most of the major barriers against the acceptance of panspermia have been demolished when it has been shown that microorganisms can survive the high impact and velocity experienced during the ejection from one planet, the journey through space, and the impact process onto another world.

Question 2

A total of 145 putative bacteriocin gene clusters were identified in 43 cyanobacteria (Figure 1, Table 1), by analyzing 58 complete and partial genomes from strains with diverse genomic structures and various morphologies. These gene clusters were classified into seven groups by comparison of their diverse gene organization and domain composition. Group I was the most abundant type with 57 gene clusters and present in one to three copies in all but one cyanobacterial genomes.

Group II was the second most abundant type, and possess 23 gene clusters found in fifteen genomes. A total of 19 group III bacteriocin gene clusters appeared in twelve strains. Gene clusters encoding LanM proteins were classified as group IV in this study. Cyanothece PCC 7425 and Nostoc punctiforme PCC 73102 each have four LanM encoding gene clusters, the other strains each have only one. Twelve gene clusters belong to group V were found in nine genomes. The gene clusters of group VI were defined as the presence of proteins with S8 peptidase domain, and mostly found from filmentatous diazotrophic strains (Table 1). Group VII had three members found in Cyanothece PCC 7425, Nostoc punctiforme PCC 73102, and Trichodesmium erythraeum IMS101 (Ulrih, 2009, pp. 249).

The majority of these putative gene clusters were encoded on the chromosome. However, eight gene clusters were found in plasmids from five ...