This review covers the structure, synthesis, biological activity, biosynthesis and distribution of cyanobacterial alkylresorcinols.

Four natural lactylates of chlorinated fatty acids, chlorosphaerolactylates A−D (1−4), were isolated from the methanolic extract of the cyanobacterium Sphaerospermopsis sp. LEGE 00249 through a combination of bioassay-guided and MSguided approaches. Compounds 1−4 are esters of (mono-, di-, or tri)chlorinated lauric acid and lactic acid, whose structures were assigned on the basis of spectrometric and spectroscopic methods inclusive of 1D and 2D NMR experiments. High-resolution massspectrometry data sets also demonstrated the existence of other minor components that were identified as chlorosphaero(bis)lactylate analogues. The chlorosphaerolactylates were tested for potential antibacterial, antifungal, and antibiofilm properties using bacterial and fungal clinical isolates. Compounds 1−4 showed a weak inhibitory effect on the growth of Staphylococcus aureus S54F9 and Candida parapsilosis SMI416, as well as on the biofilm formation of coagulase-negative Staphylococcus hominis FI31.

Cyanobacteria blooms occur frequently in freshwaters around the world. Some can produce and release toxic compounds called cyanotoxins, which represent a danger to both the environment and human health. Microcystin-LR (MC-LR) is the most toxic variant reported all over the world. Conventional water treatment methods are expensive and require specialized personnel and equipment. Recently, a multi-soil-layering (MSL) system, a natural and low-cost technology, has been introduced as an attractive cost-effective, and environmentally friendly technology that is likely to be an alternative to conventional wastewater treatment methods. This study aims to evaluate, for the first time, the efficiency of MSL eco-technology to remove MC-LR on a laboratory scale using local materials. To this end, an MSL pilot plant was designed to treat distilled water contaminated with MC-LR. The pilot was composed of an alternation of permeable layers (pozzolan) and soil mixture layers (local sandy soil, sawdust, charcoal, and metallic iron on a dry weight ratio of 70, 10, 10, and 10%, respectively) arranged in a brick-layer-like pattern. MSL pilot was continuously fed with synthetic water containing distilled water contaminated with increasing concentrations of MC-LR (0.18–10 µg/L) at a hydraulic loading rate (HLR) of 200 L m−2 day−1. The early results showed MC-LR removal of above 99%. Based on these preliminary results, the multi-soil-layering eco-technology could be considered as a promising solution to treat water contaminated by MC-LR in order to produce quality water for irrigation or recreational activities.

β-chitin, a promising biopolymer for the production of chitosan and biomaterials, is sourced from fishery by-products. Herein, β-chitin has been extracted using Deep Eutectic Solvents (DES) for the first time, only the α-polymorph having been extracted using these solvents until now. Six acid, neutral, and alkaline DES systems were trialed, with only the alkaline DES systems, in particular potassium carbonate: glycerol (KGLY) at 100 or 120 °C for 2 or 3 h, resulting in high-purity β-chitin. The ensuing β-chitin was characterized in terms of chemical and physical structure, morphology, crystallinity, and thermal properties. Under the best extraction conditions, using the DES KGLY system, the β-chitin samples were highly pure, presenting an acetylation degree between 77 and 88%, a high crystallinity between 88 and 91%, and a maximum degradation temperature of around 350 °C. Moreover, the solvent system was easily recyclable with consistent performance over 3 cycles of re-use. The extraction method is 2 well-suited for the extraction of crystalline β-chitin and could be integrated into future works in the production process of chitosan.