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Biochar is recognized as an efficient amendment and soil improver. However, environmental and quality assessments are needed to ensure the sustainability of its use in agriculture. This work considers the biochar's chemical-physical characterization and its potential phyto- and geno-toxicity, assessed with germination and Ames tests, obtaining valuable information for a safe field application. Three biochar types, obtained from gasification at different temperatures of green biomasses from the Tuscan-Emilian Apennines (in Italy), were compared through a broad chemical, physical and biological evaluation. The results obtained showed the relevance of temperature in determining the chemical and morphological properties of biochar, which was shown with several analytical techniques such as the elemental composition, water holding capacity, ash content, but also with FTIR and X-ray spectroscopies. These techniques showed the presence of different relevant surface aliphatic and aromatic groups. The procedures for evaluating the potential toxicity using seeds germination and Ames genotoxicity assay highlights that biochar does not cause detrimental effects when it enters in contact with soil, micro- and macro-organisms, and plants. The genotoxicity test provided a new highlight in evaluating biochar environmental safety.

In nature, bacteria often form heterogeneous communities enclosed in a complex matrix known as biofilms. This extracellular matrix, produced by the microorganisms themselves, serves as the first barrier between the cells and the environment. It is composed mainly of water, extracellular polymeric substances (EPS), lipids, proteins, and DNA. Cyanobacteria form biofilms and have unique characteristics such as oxygenic photosynthesis, nitrogen fixation, excellent adaptability to various abiotic stress conditions, and the ability to secrete a variety of metabolites and hormones. This work focused on the characterization of the cyanobacterium Halomicronema sp. strain isolated from a brackish environment. This study included microscopic imaging, determination of phenolic content and antioxidant capacity, identification of chemicals interfering with biofilm formation, and transcriptomic analysis by RNA sequencing and real-time PCR. Gene expression analysis was centered on genes related to the production of EPS and biofilm-related transcription factors. This study led to the identification of wza1 and wzt as EPS biomarkers and luxR-05665, along with genes belonging to the TetR/AcrR and LysR families, as potential biomarkers useful for studying and monitoring biofilm formation under different environmental conditions. Moreover, this work revealed that Halomicronema sp. can grow even in the presence of strong abiotic stresses, such as high salt, and has good antioxidant properties. [ABSTRACT FROM AUTHOR]

Macroalgae seaweeds such as Ulva lactuca and Gracilaria verrucosa cause problems on the northern coast of the Italian Adriatic Sea because their overabundance hinders the growth of cultivated clams, Rudatapes philippinarum. This study focused on the green synthesis of CuO nanoparticles from U. lactuca and G. verrucosa. The biosynthesized CuO NPs were successfully characterized using FTIR, XRD, HRTEM/EDX, and zeta potential. Nanoparticles from the two different algae species are essentially identical, with the same physical characteristics and almost the same antimicrobial activities. We have not investigated the cause of this identity, but it seems likely to arise from the reaction of Cu with the same algae metabolites in both species. The study demonstrates that it is possible to obtain useful products from these macroalgae through a green synthesis approach and that they should be considered as not just a cause of environmental and economic damage but also as a potential source of income. [ABSTRACT FROM AUTHOR]

When applied in the same concentration to tomato plants, cadmium sulfate (CdSO4) and zinc sulfate (ZnSO4) were transported from soil to roots and from roots to shoots more readily than their nano counterparts: cadmium sulfide quantum dots (CdS QD) and zinc sulfide quantum dots (ZnS QD). Compared to the CdS QD, he higher rate of transport of CdSO4 resulted in a greater negative effect on growth, chlorophyll content, antioxidant properties, lipid peroxidation and activation of antioxidant defence systems. Although ZnSO4 was transported more rapidly than ZnS QD, the overall effect of Zn addition was positive (increase in total plant mass, stem length, antioxidant content and decrease in lipid peroxidation). However, these effects were more pronounced in the case of ZnS QD, suggesting that the mechanisms underpinning the activity of ZnS QD and ZnSO4 were different. Thus, the risk of phytotoxicity and food chain transfer of the two elements depended on their form (salt or nanoform), and consequently their effects on plants' growth and physiology were different. This work elucidates the mechanisms underlying the responses of CdS QD and ZnS QD in contrast to those of their corresponding salts on tomato plants. Our results showed that faster transport from roots to leaves in the case of salts in respect to the nanoform augment their detrimental impact on tomato's antioxidant properties and growth and make the nanoform of both a better alternative for crop application either as fertilizers or as pesticides. [ABSTRACT FROM AUTHOR]