Nocardia
The phylogenetic family Nocardiopsaceae represents 24 distinct species of filamentous organisms, what differentiates them from other species of filamentous actinomycetes are several unique phenotypical characteristics. Foremost among these is halotolerance, or the ability to survive and thrive in environments with higher levels of salinity than normal, e.g. hyper saline lakes or salt marshes. These levels would ordinarily lead to chronic dehydration of an organisms cells due to the extreme solute concentration of the surrounding environment. Nocardiopsaceae possess a specific chemical makeup which allows them to present with halotolerance, granting them the ability to grow and colonise areas which are inaccessible to other organisms.
This ability to grow both in the presence of and without NaCl suggests that the gene coding for haloteolerance in N. halophila was acquired from an outside source due to a chance encounter with another organism. Further reinforced by the fact that most organisms that present halotolerance are single-celled archaea, making incorporation into the genome relatively simple when compared to a much more complicated, multi-cellular eukaryotic organism. It does however, still occur, despite implicit complications. This process of genetic uptake and incorporation is almost identical to that which lead to mitochondria being incorporated into animal cells, or chloroplasts into plants and occurs due to endosymbiosis or horizontal gene transfer. This transfer facilitated the independence of cells and allowed larger, more complex organisms to form
Refrences:
http://en.wikipedia.org/wiki/Horizontal_gene_transfer
http://upload.wikimedia.org/wikipedia/commons/d/dc/Lake_Assal_3-Djibouti.jpg
Characterising a new group of filamentous organisms is difficult, mostly due to the phenotypic similarity between filamentous actinomycetes for example, species within the nocardiopsis genus (a member of Nocardiopsaceae family) and the Saccharotrhix genus cannot be differentiated based purely on morphological features. One of said features is a non-acid fast cell wall, due to a lack of mycolic acid.
Due to the similarity between species and genus in the filamentous actinomycetes, chemotaxonomic marker analysis is combined with DNA screening methods to distinguish between organisms. These techniques were used to identify many of the nocardiopsis species and also lead to many organisms previously incorporated into this genus to be identified as belonging to other families. (* chemotaxonomic markers are substances such as fatty acids and amino acids.)
Nocardiopsis halophila is a gram positive bacteria isolated from saline soil, it shows carbon utilisation from a variety of sources and displays the highest levels of halotolerance seen in a filamentous actinomycete species. It can be identified phenotypically by its long, dense and highly branched mycelium. This mycelium is typically branched in an irregular, zigzag pattern and sporulation from the aerial mycelium produces white spores with smooth surfaces and are of varying sizes. It is also possible to identify using chemotaxonomy to isolate specific acids produced upon breakdown of previously mentioned carbon sources.
N. halophila grows best at sodium chloride concentrations of up to 20%, but it also has the unique characteristic of being able to survive in non-saline conditions, without cell lysis occurring. A feature other halophiles are unable to match due to extremely high solute concentrations in their cytoplasm. N. halophila is able to survive on media completely devoid of NaCl, it is required for anything approaching optimal growth.