When we think about marine life the big stuff usually springs to mind: fish, sharks and whales. But these iconic creatures are far outnumbered by their much smaller, much older, distant relatives. Christine Campbell gives us a… glimpse into the world of microbes and the many things they can tell us.
They may be invisible to the naked eye, but microbes make up a surprising 90 per cent of ocean life and are amongst the oldest forms of life on Earth.
Blue-green algae (cyanobacteria) are well known – mostly as a nuisance – but not many people realise quite how ancient these organisms are, with examples dating back around 3.4 billion years. With such a long history it should be no surprise that microbes appear on nearly every branch of the tree of life. They flourish in a huge range of environments, from shallow seas to hydrothermal vents and the frozen poles. Marine microbes form the base of the ocean food chain, drive global nutrient cycles and have a major influence on our climate.
Microbes are staggeringly diverse. They include protozoans, unicellular and chain-forming colonial algae and cyanobacteria, and these groups themselves contain thousands of species, each with unique characteristics. Some cyanobacteria can tolerate extremely low oxygen and light levels and are even resistant to UV radiation, which enables them to thrive in areas inhospitable to most other life-forms such as hot springs.
Despite their unrivalled abundance, their size and capacity to inhabit extreme environments makes microbes rather difficult to study. It is time-consuming and expensive to collect samples and not everyone who wants to study them has the time or resources to collect, isolate or cultivate microbes for themselves.
So specialist labs called culture collections play host to different strains of microbes collected on research cruises and field trips, creating just the right conditions to keep them alive for future study.
The Culture Collection of Algae and Protozoa (CCAP) lives at the Scottish Association for Marine Science in Oban. CCAP hosts around 3000 strains of algae, cyanobacteria and protozoa and is the most diverse collection of its kind in the world. It is in reality like a microscopic botanic gardens and zoo combined, but as a scientist you can take the plants or animals home, or at least to your own lab!
Some of CCAP’s microbe strains have been kept alive for over a century. The collection was started by Professor E G Pringsheim, a German academic who came to England in 1938. Pringsheim isolated more than 150 different strains, many in the 1920s and 30s when he worked in Prague, and they are still growing at CCAP today. New strains are regularly added from samples collected by NERC-funded scientists taking part in research cruises in polar regions and elsewhere and CCAP now hosts samples that originated in the Arctic, Chile, South Africa, Japan and Alaska as well as from waters around the UK and Europe.
Looking after these tiny pets is no easy task. Most of the strains live in test tubes in a specially formulated water-based solution or on the solid growth medium called agar. As most strains will only tolerate certain environmental conditions, the test tubes are kept in different rooms each maintained at a constant temperature under standardised light regimes. Almost all the strains have to be transferred regularly (on average monthly) into fresh medium to keep them alive – a delicate and laborious process. In some cases strains are maintained through cryopreservation, which involves keeping them in suspended animation in liquid nitrogen at -196ºC where they can last without deteriorating for hundreds of years.
We go to so much trouble because these ancient and diverse organisms have so much to teach us.
The fact that some strains can only tolerate quite specific conditions makes them useful biomarkers – by matching ‘fossil chemicals’ in sedimentary rocks with similar chemicals found in cultures held in CCAP today we can get a picture of ancient climates and environmental change. Microbes have a major influence on the environment; they are responsible for 50 per cent of global oxygen evolution and have even been explored as tools for bioengineering our environment to reverse climate change.
Their unique biological properties also means some CCAP microbes have a much more direct influence on our everyday lives. Microbiologists and biotechnologists around the world study the chemical compounds behind the microbes’ exceptional properties to see if they can isolate and mimic them for the benefit of we humans: a UV-resistant compound, for example, could be invaluable in our sun creams.
Marine algae have been found to contain a number of compounds which are now ingredients in many everyday products. The pigment that gives blue-green algae Spirulina its colour and is the source of the pink colour of the lesser flamingo – beta-carotene – is used as a food colouring. Other compounds from algae have been found to be useful in a wide range of pharmaceutical, cosmetic and nutritional products.
For companies striving to create more ‘natural’ products in particular, the marine microbial world is an important and relatively untapped resource. CCAP supplies many strains to commercial companies on the hunt for natural ingredients, new sources of lipids for human or animal foods and bioactives with the potential to produce new antibiotics or compounds with anti-cancer activity. In addition, it acts as an official international depository authority for patent organisms, maintaining patent strains for a fee and supplying them only to the depositor or those who have paid to access the strain.
The potential for marine products extends far beyond everyday consumer products or bioactives. Marine algae are being researched as a source of oil for biofuels and other petrochemical replacements. Initial studies have shown that some species of marine microalgae could provide up to ten times more oil per hectare of land than any terrestrial crops currently being used, without compromising valuable freshwater resources.
Microbes can also be a really engaging way to enthuse people about science. Pyrocystis lunula is a bioluminescent dinoflagellate – it glows in the dark and is the source of the glittering light you sometimes see in the sea at night. CCAP has supplied samples to schools and to TV companies making children’s programmes, and the pretty microbe has been the inspiration for and star of several art installations.
Supporting everything from crucial climate change research to the natural products revolution, the benefits of collections like CCAP are as diverse as their tiny house-guests.
View original article at: It’s a microbial world