A new genus of cyanobacteria has been described and published in the latest issue of the journal Phycologia. The paper, entitled ‘Systematics and biogeography of sciophilous cyanobacteria; an ecological and molecular description of Albertania skiophila (Leptolyngbyaceae) gen. et sp. nov.’, is authored by Gabrielle Zammit, a resident academic at the University of Malta.
These newly described bacteria are photosynthetic and are among the most primitive microorganisms. The type strain of the genus, Albertania skiophila SA373 was isolated from the Sancta Sanctorum chamber at St Agatha Crypt and Catacombs in Rabat, Malta. Apart from having a particular ecology, the genus is diagnosed on the basis of genetic sequences and their unique secondary folding structures.
The six cyanobacterial strains included in this new genus are made up of very thin filaments of minute blue- green cells, 2-3 µm in diameter, which are morphologically cryptic. They form phototrophic biofilms on calcareous substrata in ancient hypogea situated around Malta and Italy. Their blue green colouration (shown in the first image) is due to the presence of the phycobilin pigments phycoerythrin and phycocyanin (shown in the second image), which enable the cyanobacteria to photosynthesise at low-light intensities.
Another feature which confers an advantage to these microorganisms, enabling them to survive on rocky surfaces, is the filamentous mode of life and phototactic responses allowing them to glide towards the light. The production of copious exopolymeric substances enables the filaments to adhere to the substrate and to form microbial films that occupy a specific niche within the ecosystem.
Another feature which confers an advantage to these microorganisms, enabling them to survive on rocky surfaces, is the filamentous mode of life and phototactic responses allowing them to glide towards the light. The production of copious exopolymeric substances enables the filaments to adhere to the substrate and to form microbial films that occupy a specific niche within the ecosystem.
Molecular and phylogenetic analyses show that all strains are closely related (98% or higher DNA identity) and distantly related to all other established cyanobacterial taxa (DNA identity lower than 95%). These cyanobacteria have only been isolated from subterranean environments in Malta and Italy so far, and considering this unique biotope and their particular ecology, the new genus and species Albertania skiophila were proposed. The genus Albertania is named after Professor Patrizia Albertano, who was an an eminent phycologist and was Dr Zammit’s Ph.D. supervisor. The species name skiophila is derived from ancient Greek and means ‘shade tolerant’. The new genus is described and named in accordance with the nomenclatorial recommendations of both the Bacteriological Code and the Botanical Code of Nomenclature.
Dr Gabrielle Zammit is a lecturer at the Department of Biology, University of Malta. She leads the Labs of Microbiology and Applied Phycology (shown in the third image), where the biodiversity of microbial communities is elucidated and new taxa of microorganisms and their metabolic processes are characterised.