Permanent growth on a stony substrate

Multispecies cyanobacterial communities (biofilms, the “blooming” phenomenon) may constantly develop and vegetate for a long time on various dense media, including soil and stony substrates. These communities are of interest both theoretically and practically. Some specific features of such biofilms are due to the fact that in addition to phototrophs (algae and cyanobacteria), they include heterotrophic bacteria, micromycetes, protozoa, rotifers. I.e., a classical trophic network is observed in such microbial cenoses, which makes it possible for such consortia to exist for a long time, primarily due to the ability of cyanobacteria to autotrophic nutrition in terms of carbon (photosynthesis) and nitrogen (nitrogen fixation), which ensures their stability not only in stable environmental conditions, but also in stressful situations. From a practical viewpoint, cyanobacterial biofilms could find application in biotechnology in such areas as biosorption and the synthesis of exometabolites of various directions. In addition, they could be useful in connection with the operation of various buildings made of a material similar to that which served as a substrate for the growth of these microorganisms in our experiment. The studied biofilms were maintained for 15 years in a model experiment on a stony substrate. Our analyzes carried out to determine the qualitative and quantitative composition of the phototrophic component of these biofilms, their antifusarium activity, the content of pigments and the concentration of heavy metals showed that the growths were characterized not only by morphological differences, but also by significant differences in the determined indicators depending on the nature of growth. Within this stony substrate, three different types of biofilms and specific growths on the walls of the container which the cultivation took place in were identified.