Phyllosilicates as protective habitats of filamentous cyanobacteria Leptolyngbya against ultraviolet radiation

Cyanobacteria Boring Limestones in Freshwater Settings-Their Pioneering Role in Sculpturing Pebbles and Carbonate Dissolution

In freshwater lakes and rivers, cyanobacteria belonging to the family Leptolyngbyaceae bore > 1 mm deep into limestone pebbles by dissolving carbonate at the tip of their 3-8 μm-thick filaments. The abundance of these borings decreases downward while it is so high at the rock surface that micrometric debris is formed. Moreover, the disintegrated material on the pebbles' surface can be easily removed, for instance, when pebbles are grinding against each other due to wave or current action or when insect larvae settle and scratch loosened grains from the surface while constructing their cases. After a larvae case has been abandoned, it decays with time and the surface benath it is colonized again by boring cyanobacteria. These processes can alternate repeatedly and lead to a sculptured appearance of the pebbles, especially because insect larvae tend to colonize already existing depressions where they are better protected from predation and where they can access suspended food more easily. In the sculptures entrenched by insect larvae, larvae of byssate bivalves like Dreissena polymorpha may settle. When growing, these bivalves also remove loosened carbonate from the bored surface. Thus, boring cyanobacteria play a pioneering, preconditioning role in the morphological evolution of limestone (pebble) surfaces by transforming an initially hard substrate into a firm- to softground that is subsequently colonized and structured by animals. Consequently, sculptured pebbles are the product of multiphase, preconditioned bioerosion. Ultimately, the synergistic effects of these bioerosive processes result in the dissolution of carbonate leading to a maximum take-up of approximately 0.5-0.8 kg CO2 per square meter and year, as a preliminary estimate indicates.

Biological assessment and radiological impact in Keana, North Central Nigeria: environmental implication and metabolites production

The objective of the research was to examine microbial characteristics, metabolites produced, and the potential radiological risks present in mining soils located in Keana, North Central Nigeria. Soil samples were collected from various locations within Keana, Nasarawa State. Bacterial isolation was carried out, and molecular techniques were employed to characterize the bacteria found in the collected soil samples. Additionally, the susceptibility of these isolates to antibiotics was determined, and the bacteria screened for their ability to produce metabolites. The isolated bacteria were classified into three groups: Actinobacteria, Firmicutes, and Proteobacteria. The analysis of the spectra revealed that 1595 compounds were produced, including carboxylic acids, nitro compounds, aldehydes, anhydrides, esters, ketones, amides, phenols, alcohols, alkanes, alkenes, alkynes, and arenes. Some of the metabolites produced were oleic acid, 1,3-dioxolane, linoelaidic acid and oleic acid, 1-nonadecene, butylated hydroxytoluene, diisooctyl phthalate, bis(2-ethylhexyl) phthalate among others, and 1,2-benzenedicarboxylic acid (85.32%) as the most produced metabolite. Among the antibiotics tested, levofloxacin and ciprofloxacin exhibited the strongest antibacterial properties against the isolates. Airborne gamma-ray spectrometry analysis identified elevated levels of potassium, thorium, and uranium in the soils, indicating potential environmental hazards. However, no significant correlation was found between the presence of bacteria and radioactive elements. These findings emphasize the importance of comprehensive environmental monitoring in Keana to address potential health risks associated with microbial contamination and radioactive materials. Additionally, the study highlighted the role of microbial diversity in Keana soils in promoting the production of secondary metabolites with potential applications in pharmaceutical and industrial sectors..

Identification and Composition of Cyanobacteria in Ecuadorian Shrimp Farming Ponds-Possible Risk to Human Health

Toxic cyanobacterial blooms in various water bodies have been given much attention nowadays as they release hazardous substances in the surrounding areas. These toxic planktonic cyanobacteria in shrimp ponds greatly affect the survival of shrimps. Ecuador is the second highest shrimp producing country in the Americas after Brazil; and the shrimp-based economy is under threat due to toxic cyanobacterial blooms in Ecuador shrimp ponds. This study investigated the abundance of different cyanobacteria in the shrimp ponds at the Chone and Jama rivers (in Manabi province) at Ecuadorian pacific coast, focusing on different environmental factors, such as temperature, pH, salinity, and light. Temperature and pH were identified as key factors in influencing the abundance of cyanobacteria, with a significant positive correlation between Raphidiopsis raciborskii and pH. The highest and lowest abundance of cyanobacteria found during the dry season in the shrimp ponds near the Chone and Jama rivers were > 3 × 106 and 1 × 106 Cell.m-3, respectively. The Shannon-Wiener Diversity Index fluctuated between 0.41-1.15 and 0.31-1.15 for shrimp ponds of Chone and Jama rivers, respectively. This variation was linked to changes in salinity and the presence of harmful algal blooms, highlighting the importance of continuous monitoring. Additionally, the study areas showed eutrophic conditions with low diversity, underlining the need for additional spatiotemporal studies and expanded research in both rivers, to better understand these complex phenomena. The findings underscore the importance of continuous monitoring and expanded research in cyanobacteria ecology, with implications for public health and aquatic resource management.

A critical review of mineral-microbe interaction and coevolution: mechanisms and applications

The mineral-microbe interactions play important roles in environmental change, biogeochemical cycling of elements, and formation of ore deposits. Minerals provide both beneficial (physical and chemical protection, nutrients, and energy) and detrimental (toxic substances and oxidative pressure) effects to microbes, resulting in mineral-specific microbial colonization. Microbes impact dissolution, transformation, and precipitation of minerals through their activity, resulting in either genetically-controlled or metabolism-induced biomineralization. Through these interactions minerals and microbes coevolve through Earth history. The mineral-microbe interactions typically occur at microscopic scale but the effect is often manifested at global scale. Despite advances achieved through decades of research, major questions remain. Four areas are identified for future research: integrating mineral and microbial ecology, establishing mineral biosignatures, linking laboratory mechanistic investigation to field observation, and manipulating mineral-microbe interactions for the benefit of humankind.

An overview of experimental simulations of microbial activity in early Earth

Microbial activity has shaped the evolution of the ocean and atmosphere throughout the Earth history. Thus, experimental simulations of microbial metabolism under the environment conditions of the early Earth can provide vital information regarding biogeochemical cycles and the interaction and coevolution between life and environment, with important implications for extraterrestrial exploration. In this review, we discuss the current scope and knowledge of experimental simulations of microbial activity in environments representative of those of early Earth, with perspectives on future studies. Inclusive experimental simulations involving multiple species, and cultivation experiments with more constraints on environmental conditions similar to early Earth would significantly advance our understanding of the biogeochemical cycles of the geological past.

Regulation of antioxidant defense and glyoxalase systems in cyanobacteria

Oxidative stress is common consequence of abiotic stress in plants as well as cyanobacteria caused by generation of reactive oxygen species (ROS), an inevitable product of respiration and photosynthetic electron transport. ROS act as signalling molecule at low concentration however, when its production exceeds the endurance capacity of antioxidative defence system, the organisms suffer oxidative stress. A highly toxic metabolite, methylglyoxal (MG) is also produced in cyanobacteria in response to various abiotic stresses which consequently augment the ensuing oxidative damage. Taking recourse to the common lineage of eukaryotic plants and cyanobacteria, it would be worthwhile to explore the regulatory role of glyoxalase system and antioxidative defense mechanism in combating abiotic stress in cyanobacteria. This review provides comprehensive information on the complete glyoxalase system (GlyI, GlyII and GlyIII) in cyanobacteria. Furthermore, it elucidates the recent understanding regarding the production of ROS and MG, noteworthy link between intracellular MG and ROS and its detoxification via synchronization of antioxidants (enzymatic and non-enzymatic) and glyoxalase systems using glutathione (GSH) as common co-factor.