Comparison of the Peel-Associated Epiphytic Bacteria of Anthocyanin-Rich “Sun Black” and Wild-Type Tomatoes under Organic and Conventional Farming

Tomatoes are among the most consumed vegetables worldwide and represent a source of health-beneficial substances. Our study represents the first investigating the peel-associated epiphytic bacteria of red and purple (anthocyanin-rich) tomatoes subjected to organic and conventional farming systems. Proteobacteria was the dominant phylum (relative abundances 79–91%) in all experimental conditions. Enterobacteriaceae represented a large fraction (39.3–47.5%) of the communities, with Buttiauxella and Atlantibacter as the most represented genera. The core microbiota was composed of 59 operational taxonomic units (OTUs), including the majority of the most abundant ones. The occurrence of the most abundant OTUs differed among the experimental conditions. OTU 1 (Buttiauxella), OTU 2 (Enterobacteriales), and OTU 6 (Bacillales) were higher in red and purple tomatoes grown under organic farming. OTU 5 (Acinetobacter) had the highest abundance in red tomatoes subjected to organic farming. OTU 3 (Atlantibacter) was among the major OTUs in red tomatoes under both farming conditions. OTU 7 (Clavibacter) and OTU 8 (Enterobacteriaceae) had abundances 1% only in red tomatoes grown under conventional farming. PCA and clustering analysis highlighted a high similarity between the bacterial communities of red and purple tomatoes grown under organic farming. Furthermore, the bacterial communities of purple tomatoes grown under organic farming showed the lowest diversity and evenness. This work paves the way to understand the role of nutritional superior tomato genotypes, combined with organic farming, to modulate the presence of beneficial/harmful bacteria and supply healthier foods within a sustainable agriculture.Filas project MIGLIOR

Persistence of Enterobacteriaceae Drawn into a Marine Saltern (Saline di Tarquinia, Italy) from the Adjacent Coastal Zone

Enterobacteriaceae is present in various niches worldwide (i.e., the gastrointestinal tracts of animals, clinical specimens, and diverse environments) and hosts some well-known pathogens (i.e., salmonellas, shigellas and pathogenic coliforms). No investigation has focused on its occurrence in marine salterns, and it is not clear if these hypersaline environments could be a reservoir for these bacteria including some potentially harmful members. In this study, a two-year metabarcoding survey was carried out on samples collected from different ponds of the “Saline di Tarquinia” salterns and the nearby coastal waters. Enterobacteriaceae was recorded almost constantly in the seawaters feeding the saltern. Its abundance was generally higher in the sea than in the ponds, probably due to the higher anthropic impact. The same trend was evidenced for the key genus (Escherichia/Shigella) and OTU (OTU 5) of the Enterobacteriaceae community. Various parameters affected taxon/OTU abundance: Enterobacteriaceae, Escherichia/Shigella and OTU5 decreased with increasing salinity and rains; moreover, Escherichia/Shigella and OTU 5 were higher in autumn than in spring. Although Enterobacteriaceae did not seem to find the most favourable conditions for a high-abundance persistence in the saltern environment, it did not disappear. These observations suggested this environment as a potential reservoir for bacteria with possible important health implications

Advances in Chitin and Chitosan Science

Chitin is among the most abundant natural polysaccharides [...

Could Pontimonas Harbour Halophilic Members Able to Withstand Very Broad Salinity Variations?

Pontimonas is currently described as a genus including only one species of slightly halophilic marine bacteria. Although some works revealed its presence in some hypersaline environments, the information on its habitat preference is still scant. This work investigated Pontimonas presence in selected ponds of the Saline di Tarquinia marine saltern and in the seawater intake area. The two-year metabarcoding survey documented its constant presence along the ponds establishing the salinity gradient and in a distinct basin with permanent hypersaline conditions (BSB). Pontimonas was higher in the ponds than in the sea, whereas it had similar abundances in the sea and in the BSB. Its representative OTUs showed significant trends according to different parameters. Along the salinity gradient, OTU1 abundance increased with decreasing water temperatures and increasing rainfalls, and it showed a maximum in January; OTU2 increased with increasing BOD5 and it showed the highest abundances in the period August–October, and OTU 3194 increased at decreasing salinities. In BSB, a significant seasonal variation was shown by OTU 3194, which started increasing in spring to reach a maximum in summer. The results suggest that Pontimonas could easily settle in hypersaline habitats, having also broad euryhaline members and some possible extreme halophilic representatives

Editorial: Mining, Designing, Mechanisms and Applications of Extremophilic Enzymes

Enzymes play very important roles in industrial and environmental biotechnology. Their value has increased in recent decades mainly in food and detergent industries and is still growing, particularly in bioremediation (white biotechnology), and in medical, pulp/paper, textile, energy, and biosensor applications (Fernández-Lucas et al., 2017). Recent assessments have evaluated the global enzyme market at more than $7,000 million, and the business is estimated to rapidly exceed$10,000 million (Fernández-Lucas et al., 2017; Pasqualetti et al., 2019). Enzyme technologies provide economically viable and eco-friendly alternatives. The number of commercial enzymes continues to increase as we exploit, by traditional or molecular screening/selection methods, the astonishing microbial diversity to obtain new bio-catalysts and expand their range of application (Petruccioli et al., 1993; Xiao et al., 2015; Sysoev et al., 2021). Most extremophilic enzymes (extremozymes) come from microorganisms. Extremozymes remain active and stable in extreme conditions, such as high pH values, high salinity and hydrostatic pressure, and temperature extremes. They often have unique properties empowering them to satisfy the needs of many harsh industrial processes. From a commercial viewpoint, enzymes with high activity and adaptation to diverse extreme conditions show growing demand, since current applications of many existing enzymes are still constrained by activity, stability, and/or economic issues. One solution to this problem is searching for new enzymes from natural sources that show high activity/stability, uncommon specificity, and poly-extremophilic features (thermo/psychrophilic, acid/alkalophilic, and halophilic properties). However, not all extremozymes are isolated from extreme environments. Another winning strategy, which is expected to improve enzyme properties for biotechnological application, is protein engineering (Xiao et al., 2015; Liu et al., 2019). The objective of this Research Topic was to inspect new details in this growing research field, and to obtain a deeper understanding of the area, allowing us to outline its state-of-the-art: by showing enzymes that have high activity and stability in extreme or poly-extreme conditions; understanding their relative adaptation mechanisms; reporting successful mining, designing, characterization, and production of novel extremophilic enzymes also by bioinformatic tools. We cover 15 manuscripts that explore different aspects of this Research Topic.s