Cyanobacteria are fascinating organisms that appeared on our planet more than 3.5 billion years ago. They are photosynthetic bacteria that live in the aquatic environment and over more than 1 billion years were able to modify the chemical composition of an atmosphere in which life, as we know it today, would be impossible.
They have been able to survive all major planetary catastrophes and can be found today in a multitude of habitats, even in extreme environments such as polar ice caps or deserts.
Under certain conditions, they can live out of water, generally forming films on the surface of rocks or any other material, almost always in environments with high humidity and as long as light is present.
The environment of the "Ares Station" in the Escalón cave (Cantabria) is an ideal place for the development of cyanobacterial biofilms and is of great interest from the point of view of applied biology.
Caves can be a good habitat for these creatures, but when they grow on the surface of these hollows, they tend to form biofilms that are not very developed or rich in biodiversity due to the limiting conditions of these environments.
Appearance of the biofilms with the naked eye when illuminated with UV light at 360nm. The whitish masses correspond to filamentous cyanobacteria of the genera Timaviella and Geitleria.
The environment of the "Ares Station" in the Cueva del Escalón (Cantabria, Spain) has proved to be one of the most favourable environments known for the development of cyanobacterial mats and an ideal setting for research of various kinds, particularly in Astrobiology.
The "Ares Station" is an operations centre of the company "Astroland Agency", installed inside the cave itself, from where part of the biofilm research is carried out, mainly supporting sampling and fieldwork activities.
The "Ares Station" is an operations centre of the "Astroland Agency" company, installed inside the Cueva del Escalón, from where part of the biofilm research is carried out, mainly supporting sampling and fieldwork activities.
It is a facility that respects the environment in which it is located, and from where an interesting astrobiology programme is being developed, in which different protocols related to microbiological research and the appearance of life on our planet, or the search for signs of life on Mars, are being tested.
In the biofilms that develop on the humid limestone walls of its surroundings, very heterogeneous masses of cyanobacteria flourish, forming biofilms of very varied appearance, very rich in species and of a captivating beauty in which the gelatinous or powdery textures of some species intermingle with other filamentous, tangled or spongy ones in a show of exceptional colours, which make this place a "Sistine Chapel", capricious in its forms and overflowing with life and colours.
Under the epifluorescence microscope at 100x magnification, the main cyanobacterial masses and the structure of the formations of the different species can be seen in detail. Motic Panthera C2 Trinocular, with FLED epi-fluorescence module. Motic Plan UC 10X/0.25/Ph1 objective.
All this beauty is accompanied by exceptional interest, not least because among the cyanobacterial microorganisms and other very primitive photosynthetic life forms such as the cyanidaceae, found here, are some of the most primitive forms of photosynthetic life known on our planet. Gloeobacter violaceus, a cyanobacterium related to the most primitive photosynthesising ancestors, was found in this cavity along with a number of taxa that are possibly new to science and are now being studied in the Dept. of Integrative Biotechnology at the University of California, USA. Integrative Biotechnology of the University of Applied Sciences Kaiserslautern, by Michael Lakatos and Patrick Jung, together with Dennis J. Nuernberg, at the Institute of Experimental Physics of the Freie Universität Berlin, who are completing the work initiated by us at the "Ares Station" through the Water Project.
The study of the photosynthetic activity of some cyanobacteria in situ is key to understanding their metabolism and some of their survival strategies.
The potential industrial, pharmacological, dietary and bioremediation applications that these organisms apparently present open up an exciting panorama in the field of biotechnology and hypotheses about how the first photosynthetic organisms arose on our planet and the relationship with some mineral compounds that could provide alternative sources of photosynthetic activation to that of light radiation.
Optical microscopy is playing a fundamental role in identifying the microorganisms that constitute the biofilms and their vital processes and in this sense the equipment that Motic Europe has generously lent us temporarily, a Motic Panthera CC trinocular microscope equipped with the FLED module and provided with a condenser and objectives for observation with phase contrast and dark field, is being a very valuable working tool, with which we have taken the microscopic images that accompany this article.
The images shown here show some of the most common forms of growth in these biofilms, on the one hand the filamentous formations and on the other the powdery ones, in addition to the more abundant gelatinous ones, such as Gloeobacter violaceus, already mentioned in a previous article.
Cyanidium sp. cells observed at 200x magnification with the UV epi-illumination module. The cell outlines and the low photosynthetic activity in the sample are highlighted in the image. Motic Panthera C2 Trinocular, with FLED epi-fluorescence module. Motic Plan UC 20X/0.45/Ph2 objective.
Almost as Martian as Mars itself, although tinged with green, the Cyanidiophyceae are an ancestral group of algae that develop inside the cave in very poorly lit areas. Little is known about them as much as about the red planet, little more than that they are a living treasure, another in this astrobiological adventure that puts us on the trail of the first steps of life of eukaryotic organisms on Earth.
In their morphology, the spherical shapes of these tiny algae, barely 5 microns in diameter, are very reminiscent of Cyanidium, with a green chloroplast and a differentiated nuclear structure that almost always occupies the central part of the cell, all protected by a thick wall that protects it from drying out, and so they live in small groups while retaining their individuality, on a slightly different basic substrate to that described for Cyanidium caldarium and on which further research will have to be carried out.
Cyanidium sp. cells observed at 400x magnification with the UV epi-illumination module. The cell outlines and the low photosynthetic activity in the sample are highlighted in the image. Motic Panthera C2 Trinocular, with FLED epi-fluorescence module. Motic Plan UC 40X/0.65/Ph2 objective.
Members of the class Cyanidiophyceae are considered to be pre-Rhodophytes and may represent a transitional algal model linking cyanobacteria with unicellular rhodophyceae. This group of algae, often living in thermal and acidic waters, is composed of three genera represented by a small number of species.
The images shown here, taken with dark-field and epifluorescence techniques, show their circular outlines and show which cells are active when their photosynthetic pigments fluoresce red.
Filamentous colonial forms of the genera Timaviella and Geitleria in the biofilm observed with polarised light at 400x magnification.
Motic Panthera C2 Trinocular, with epifluorescence FLED module. Motic Plan UC 40X/0.65/Ph2 objective and polarisers.
The filamentous tangles shown in the images correspond mainly to the cyanobacterial genera Timaviella and Geitleria, which metabolise CO2 in their photosynthesis, generating calcium carbonate as a by-product with which they synthesise the fibrous sheaths in which they live protected.
All these microorganisms are very efficient carbon dioxide fixers and, given their metabolic and genetic particularities, they are a priori excellent candidates for the development of atmospheric bioremediation processes together with other cyanobacteria that are capable of photosynthesis under very low light conditions.
Filamentous colonial forms of the genera Timaviella and Geitleria in the biofilm observed with darkfield at 400x magnification. Motic
Panthera C2 Trinocular, with epifluorescence FLED module. Motic Plan UC 40X/0.65/Ph2 objective.
Similarly, the extracellular matrix of many of the cyanobacteria living in these biofilms are very rich in glycoprotein compounds and have very interesting antibiotic, nutritional and other properties, which have hardly been explored and open up an interesting and promising field of applied research.
Copyright: Antonio Guillén
Proyecto Agua - by Antonio Guillén