Draft Genome Assembly of a Filamentous Euendolithic (True Boring) Cyanobacterium, Mastigocoleus testarum Strain BC008

Biodeterioration of stone and metal - Fundamental microbial cycling processes with spatial and temporal scale differences

Fundamental processes for the biodeterioration of stone and metal involve many of the same microbially mediated reactions - oxidation, reduction, acid dissolution and elemental cycling - resulting from the activities of many of the same groups of environmental microorganisms. Differences depend on the nature of the substratum - stone vs. metal - and the composition of the surroundings, whether terrestrial (stone) or aquatic (stone and metal). Reactions within surface-related biofilms dominate the biodeterioration of metals and contribute greatly to the biodeterioration of stone. In the latter, phototrophic organisms, and especially cyanobacteria, are important first participants, while metal biodeterioration is almost entirely associated with bacteria, archaea and fungi. Biofilms on metal surfaces can produce chemical and electrochemical responses. While electrochemical responses are absent in stone, extracellular electron transfer can be a biodeterioration mechanism in some iron-rich rocks. Microorganisms in biofilms can penetrate and create fissures or cracks in stone and metals. However, the most obvious differences in the reactions of built stone and metal structures are related to the definition of failure, length of time required for a defined failure of the substratum, the area over which the failure occurs and the consequences of failure. Time and space are, similarly, quite distinct for biological breakdown and mineral cycling of metal and stone, with stone/rock cycling potentially occurring over thousands of years and kilometers.

The Leaf Microbiome of Tobacco Plants across Eight Chinese Provinces

Leaf microorganism communities play significant roles in the process of plant growth, but the microbiome profiling of crop leaves is still a relatively new research area. Here, we used 16S rDNA sequencing to profile the microbiomes of 78 primary dried tobacco leaf samples from 26 locations in eight Chinese provinces. Our analyses revealed that the national leaf microbial communities contain 4473 operational taxonomic units (OTU) representing 1234 species, but there is a small, national core microbiome with only 14 OTU representing nine species. The function of this core microbiome is related to processes including nitrogen fixation, detoxification of diverse pollutants, and heavy-metal reduction. The leaf microorganism communities are obviously affected by local environments but did not exhibit obvious relationships to single ecological factors (e.g., temperature, precipitation). Our findings enhance the understanding of microbial diversity of tobacco leaves, which could be utilized for a variety of bioprocess, agricultural, and environmental detoxification applications.

Succession and Colonization Dynamics of Endolithic Phototrophs within Intertidal Carbonates

Photosynthetic endolithic communities are common in shallow marine carbonates, contributing significantly to their bioerosion. Cyanobacteria are well known from these settings, where a few are euendoliths, actively boring into the virgin substrate. Recently, anoxygenic phototrophs were reported as significant inhabitants of endolithic communities, but it is unknown if they are euendoliths or simply colonize available pore spaces secondarily. To answer this and to establish the dynamics of colonization, nonporous travertine tiles were anchored onto intertidal beach rock in Isla de Mona, Puerto Rico, and developing endolithic communities were examined with time, both molecularly and with photopigment biomarkers. By 9 months, while cyanobacterial biomass and diversity reached levels indistinguishable from those of nearby climax communities, anoxygenic phototrophs remained marginal, suggesting that they are secondary colonizers. Early in the colonization, a novel group of cyanobacteria (unknown boring cluster, UBC) without cultivated representatives, emerged as the most common euendolith, but by 6 months, canonical euendoliths such as Plectonema (Leptolyngbya) sp., Mastigocoleus sp., and Pleurocapsalean clades displaced UBC in dominance. Later, the proportion of euendolithic cyanobacterial biomass decreased, as nonboring endoliths outcompeted pioneers within the already excavated substrate. Our findings demonstrate that endolithic cyanobacterial succession within hard carbonates is complex but can attain maturity within a year’s time.