Major water-polluting microplastics (for example, polyethylene, polypropylene and others) have lower density than water. Therefore, they are concentrated in the neustonic layer near the water-air interface altogether with dissolved or colloidal natural organic matter, hydrophobic cells and spores of bacteria. This can cause environmental and public health problems because the floating micro- and nanoparticles of plastics could be coated with biofilm of hydrophobic and often putative pathogenic bacteria. Biofilm-coated microplastics are more attractive for consumption by aquatic animals than pure microplastics, and that increases the negative impacts of microplastics. So, impacts of even small quantities of microplastics in aquatic environments must be accounted for considering their accumulation in the micro-layer of water-air interphase and its interaction with bacterioneuston. Microorganisms attached to the surface of microplastic particles could interact with them, use them as substrates for growth, to change properties and biodegrade. The study of microbial life on the surface of microplastic particles is one of the key topics to understanding their role in the environment.

The outer-most layer of plant surface, the cuticle, consists of epi- and intra-cuticular wax. It protects the plant from dehydration, extreme temperatures and UV radiation, as well as attacks from pests such as molds and bacteria. Berry cuticular waxes are studied to understand the metabolism character (factors affecting wax layer composition in different berry species) and increase the microbial resistance and shelf life of berries. The aim of this study was analysis of the surface wax composition of nine species of wild and cultivated berries from Northern Europe. Cuticular wax analysis were done using gas chromatography-mass spectrometry. A total of 59 different compounds were identified belonging to nine groups of compounds, namely, alkanes, phytosterols, alcohols, fatty acids, phenolic acids, ketones, aldehydes, esters and tocopherols. The analyzed blueberries had the highest amount of wax present on their surface (0.9 mg berry⁻¹), triterpenoids were the main wax constituent in these berries, with up to 62% wax composition. Berry species and varieties were compared based on their surface wax composition—similarities were found between different blueberry varieties; however, other berries showed differences based on concentration and composition of cuticular wax.

In this study, cuticular wax load, its chemical composition, and biosynthesis, was studied during development of wild type (WT) bilberry fruit and its natural glossy type (GT) mutant. GT fruit cuticular wax load was comparable with WT fruits. In both, the proportion of triterpenoids decreased during fruit development concomitant with increasing proportions of total aliphatic compounds. In GT fruit, a higher proportion of triterpenoids in cuticular wax was accompanied by a lower proportion of fatty acids and ketones compared to WT fruit as well as lower density of crystalloid structures on berry surfaces. Our results suggest that the glossy phenotype could be caused by the absence of rod-like structures in GT fruit associated with reduction in proportions of ketones and fatty acids in the cuticular wax. Especially CER26-like, FAR2, CER3-like, LTP, MIXTA, and BAS genes showed fruit skin preferential expression patterns indicating their role in cuticular wax biosynthesis and secretion.

The aim of this study was to characterize the variation in biologically active compounds, antioxidant activity and physico-chemical properties in naturally grown bilberries gathered from different sites in Northern Europe. The variability in the biologically active compounds, antioxidant capacity and physico-chemical properties, as well as the development of tools for the authenticity and quality control of wild bilberries (V. myrtillus L.) in different geographical locations was evaluated. The berries of bilberries were handpicked during the summers of 2019 and 2020 during the time periods when they are typically harvested for commercial purposes in Northern Europe (Norway (NOR), Finland (FIN), Latvia (LVA) and Lithuania (LTU)). Berries from locations in NOR were distinguished by their higher mean TPC (791 mg/100 g FW, average), whereas the mean TPC of samples from the most southern country, LTU, was the lowest (587 mg/100 g FW). The TPC of bilberries ranged from 452 to 902 mg/100 g FW. The TAC values of investigated bilberry samples varied from 233 to 476 mg/100 g FW. A high positive correlation was found between TPC and antioxidant activity of the bilberry samples (R = 0.88 and 0.91 (FRAP and ABTS assays, respectively)), whereas the correlation between TAC and antioxidant activity was lower (R = 0.65 and 0.60). There were variations in the TPC and TAC values of investigated berries, suggesting that genotype also affects the TPC and TAC in berries. In 2020, the pH values and TSS contents of berries were significantly lower than in 2019. To the best of our knowledge, this is the first comprehensive reported evaluation of the biologically active compounds in wild bilberries from different Northern European countries using one laboratory-validated method.