Myxos are NOT slime

Slime is all around us and plays an essential role in the environment. There are many organisms that produce slime. In fact, mammals turned their slimy bits inward. Slime acts as selective barriers, glues and lubricants. A snail uses its slime as a trail, often filled with pheromones to attract a mate, and as a lubricant to assist its movement in a near-frictionless manner across an environmental surface. Another example is the abalone, which uses its slime to cling to a rock surface beneath the ocean where the slime acts as a strong adhesive. Australia’s red triangle slug will secrete a mucus so strong it can trap its predator, a tree frog, to almost any surface in order to protect itself.

By Teresa Van Der Heul
Photos by John and Teresa Van Der Heul

Slimes are biofilms (about 90% water) which are highly organised structures that resemble mycelial threads, surrounded by circulating water channels that supply nutrients and remove wastes. A biofilm can contain a single species of bacteria or several species living harmoniously in a clustered group. Any bacteria can transform itself into a biofilm once it attaches to a hard surface in a moist environment. Genetic studies confirm that bacteria can switch on or off different genes, depending on whether they’re living as free-floating microbes or clustering as biofilms. Biofilms secrete a sticky carbohydrate coating to protect against an aggressive environment, continually adapting in order to contribute to the wellbeing of the whole organism.

Myxomycetes play a major role in the microbial environment of this planet. Here in Australia, there is much to learn about where they are, where they grow, what their preferred substrate is, what they feed on, how active they are in controlling other soil protists, or do they kill other soil predators?

Myxomycetes are eukaryotic cells which are functionally integrated individuals, whose evolution dates to two (so far proven) endosymbiotic events: the endosymbiosis between an α-proteobacterium and the proto-eukaryotic cell which is found on the mitochondria in the nucleus. This process (eukaryogenesis) occurred millennia ago as reported with the discovery of a fossil myxomycete from Eocene-Oligocene amber found in the Dominican Republic dated 20 to 23 million years ago. It is the only known myxomycete with the phaneroplasmodium clearly preserved. Another ancient example is that of the microbial stromatolites in Western Australia, the fossilised remains of complex slimes aged 3.5 billion years, which have slowly built over time mineralising layer by layer, year after year.

Myxomycetes have a slimy period in their life cycle when they feed as a plasmodium. If you are lucky enough to see one in the wild for the first time, look closely with a lens and see the white trail alongside the coloured, slimy, pulsating section (usually, this will change to a brownish colour as it dehydrates).

Perichaena depressa mobile plasmodium with trail
Perichaena depressa dehydrated trail

This is like a snail trail. Communication. It tells the organism “You’ve been here before, nothing to find this time, try another route”. A form of intelligence. Different species will move about together, some are happy to do this, some will fight, some will become parasitic, sometimes there is harmony and sometimes there are great wars. Sound familiar?

Physarum roseum and Metatrichia floriformis

Learning about the role of myxomycetes in the environment involves learning about many other life cycles and interactions such as symbiosis and endosymbiosis, and antibiotic and antifungal abilities of organisms. How they assist in nature with their interactions with plants, earth, invertebrates, reptiles and mammals. The importance they reveal and teach us about our own health with their anti-tumor abilities. How they are dispersed and by which animal vectors. How they have survived in extreme environments over millennia. You will also begin to understand the interactions involved with your own body, ingesting necessary earth elements and the cycles involved within, to ensure all those cycles are operating effectively.

Typical yellow plasmodium seen in the field

Myxomycetes are not slime, they are a protist that lives a life with a slimy phase, that slime being external.  

The internal is its cytoplasm which transmits signals, has receptors, and is where the nucleus continues its synchronous divisions while it is feeding. Homo sapiens, the most evolved organism on earth, has all its slimy areas internally. Mammals have evolved to protect these areas and prevent them from drying out too quickly. So, why are Homo sapiens not listening to Myxomycetes? Call them “myxos” or “myxomycetes” but not slime moulds! They produce the most exquisite fruit that really are a delight to photograph. But they do have a reason for being a part of the environment.

Physarum roseum
Arcyria obvelata

Soil protists are bacterivorous, but there are numerous interactions happening below the soil surface. Functions of soil protists are attributed to interactions with other organisms. Especially important is the role of protists in driving the microbial loop, i.e. releasing nutrients (particularly nitrogen) bound in bacterial prey. The microbial loop has been demonstrated both in aquatic and soil systems.

Echinostelium sp, one of the tiniest known myxomycete species and the one which may lack a multinucleate plasmodial stage, often appears in moist chambers on soil and fallen plant material. These tiny critters play a role in symbiosis with some of the nitrogen fixing bacteria which stimulate plant growth and nutrient cycling. They represent an essential link to life on this planet.

There are some myxomycetes that have the ability to destroy anaerobic bacteria. Some may convert the nitrous oxide, respired by the anaerobic bacteria, within the earth, back to individual elements. The oxygen stays in the earth while nitrogen expels to the atmosphere. So, while myxomycetes are doing this fungal mycelium is producing carbon dioxide and saturating the soil. Young plants are loving it and soak all that carbon up. Meanwhile myxomycete amoeba are reabsorbing their flagella prior to forming the zygote, in order to redirect tubulin from the cytoskeleton and flagellum to form the mitotic spindle in the nucleus. RECYCLING of two important proteins is less costly to the organism than making new ones, and so tubulin is used to form microtubules and actin for cell division and cell motility.

Clastoderma debaryanum

The dictyostelids (another amoeba), coat their spores with slime. The larvae of a beetle or a cicada consumes the dictyostelids fruit, and the spores have protection from digestive acids, enzymes and bacteria while in the gut. This larva is then eaten by a bird which is very mobile in flight and poops quite freely, even when on the wing. If the poop lands in the right spot, environmentally, the spores may grow. Some birds fly huge distances, some myxomycetes are carried over long distances. Myxo spores have been found in bat poop in caves and on cow poop in pastures, indicating the possibility of long-distance dispersal.

Another protist, Cryptodifflugia operculata, found together with myxomycetes in the soil, has been observed to hunt and destroy nematodes, the protist actually showed a preference for juvenile nematodes. These spores do not germinate unless they have passed through the juvenile’s gut first, indicating a co-operative existence between the two microbes. Findings such as this are of great significance for food, forestry and environmental research, along with ensuring that food production is not threatened.

How many of you have had a replacement joint, heart valve or cataract replacement? It is amazing to think that all that has only come about thanks to science and the studies in mycology! Myxomycetes produce polysaccharides which protect them from the enzymes and antibiotics produced by other micro-organisms e.g., bacteria, viruses, yeasts and other protists, including other myxos. It’s the study of these polysaccharides that has enabled science to create the replacement lens to fit into the eye. If it were not for these marvellous studies, the natural immune responses of your body would reject the foreign object. It’s these slimy coatings that cover artificial joint replacements. It’s a protein-based membrane that has been designed thanks to mycological studies.

The recent studies of the effects of methanogenic archaea in the northern hemisphere, and how the changes in microbial activity are driving the changes in methane cycling. Or the fact that changing the content of a cow’s diet can make such a difference to the amount of methane it produces from its four stomachs (you only have one with a slimy inside lined cavity, to contain and retain the hydrochloric acid produced by your digestive system, and bacteria, to process that which you ingested). Even your body is a multiple of cycles, each of which is a healthy environmental home to another group of organisms. But if one of those organisms enters another part of your body, it could kill you.

As a community, we, Homo sapiens, should expand our knowledge on climate change impacts linked to desertification, land degradation and terrestrial ecosystems, and on the ocean and atmosphere. Soil quality is key to ensure nutrient supply for plant growth. Seasonal variation affects microbial community responses to the environment, yet microbes are the foundation and engineers of global ecosystems.

Myxomycetes play an essential role in maintaining the equilibrium of all life on this planet. A provisional listing of ‘Near Threatened’ on the IUCN Red List of Threatened Species is currently listed for 20 species of myxomycetes. Here in Australia, fifteen of these have been recorded, of which we have eleven locally. We must gather more knowledge about their occurrences and environmental role. Our Australian mycologists require our assistance to keep the cycle of research in motion from children to politicians, for micro-organisms to macro-organisms, for an amino acid to a planet.

Fungi and myxos have been here far longer than Homo sapiens, yet they have learned to evolve. If Homo sapiens have evolved so far then why are they not doing more to reverse the damage they have done? Why are Homo sapiens not prepared to listen to fungi and myxos?


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