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Summary: Deciphering the fossil record of cyanobacteria is crucial to understand their role in the chemical and biological evolution of the early Earth. They profoundly modified the redox conditions of early ecosystems more than 2.4 Ga ago, the age of the Great Oxidation Event (GOE), and provided the ancestor of the chloroplast by endosymbiosis, leading the diversification of photosynthetic eukaryotes. Here, we analyze the morphology, ultrastructure, chemical composition, and metals distribution of Polysphaeroides filiformis from the 1040–1006 Ma Mbuji-Mayi Supergroup (DR Congo). We evidence trilaminar and bilayered ultrastructures for the sheath and the cell wall, respectively, and the preservation of Ni-tetrapyrrole moieties derived from chlorophyll in intracellular inclusions. This approach allows an unambiguous interpretation of P. filiformis as a branched and multiseriate photosynthetic cyanobacterium belonging to the family of Stigonemataceae. It also provides a possible minimum age for the emergence of multiseriate true branching nitrogen-fixing and probably heterocytous cyanobacteria.

In food industries, microbial contaminations are difficult to control due to the recurrent formation of biofilms that hinders antimicrobials penetration and efficiency. An understanding of Salmonella Enteritidis biofilms behavior under flow conditions is a key to develop efficient preventive and control strategies. S. Enteritidis biofilms displayed 5.96, 6.28 and 6.80 log CFU cm−2 under 0.006 cm s−1, 0.045 cm s−1, and 0.087 cm s−1 flow velocities, respectively. Biofilms exposed to higher nutrient conditions under greater flow rates, induced significantly more biofilm biomass. To control biofilms, the disinfection efficiency of thymol (THY) was assessed under dynamic conditions by encapsulation it into two types of nanocapsules: monolayer (ML) nanocapsules prepared with a single carrier material (maltodextrin), and layer-by-layer (LBL) nanocapsules prepared by combining two carrier materials (maltodextrin and pectin). A combined mixture of ML and LBL nanocapsules at ½ their minimal inhibitory concentrations induced 99.99% eradication of biofilms developed under the highest flow conditions, after 5 h. ML nanocapsules decreased significantly bacterial counts during the first 0.5 h, while LBL nanocapsules eliminated the remaining bacterial cells and ensured a protection from bacterial contamination for up to 5 h by releasing THY in a sustained manner over time due to the thicker shell wall structure.