Microbiomes associated with Coffea arabica and Coffea canephora in four different floristic domains of Brazil.

Brazilian coffee production relies on the cultivation of Coffea arabica and Coffea canephora. Climate change has been responsible for the decreasing yield of the crops in the country yet the associated microbial community can mitigate these effects by improving plant growth and defense. Although some studies have tried to describe the microorganisms associated with these Coffea species, a study that compares the microbiome on a wider spatial scale is needed for a better understanding of the terroir of each coffee planting region. Therefore, our aim was to evaluate the microbial communities harbored in soils and fruits of these Coffea species in four Brazilian floristic domains (Amazon, Atlantic Forest Caatinga, and Cerrado). One hundred and eight samples (90 of soil and 90 of fruits) were used in the extraction and sequencing of the fungal and bacterial DNA. We detected more than 1000 and 500 bacterial and fungal genera, respectively. Some soil microbial taxa were more closely related to one coffee species than the other species. Bacillus bataviensis tends to occur more in arid soils from the Caatinga, while the fungus Saitozyma sp. was more related to soils cultivated with C. arabica. Thus, the species and the planting region (floristic domain) of coffee affect the microbial composition associated with this crop. This study is the first to report microbial communities associated with coffee produced in four floristic domains that include sites in eight Brazilian states. Data generated by DNA sequencing provides new insights into microbial roles and their potential for the developing more sustainable coffee management, such as the production of biofertilizers and starter culture for fermentation of coffee cherries.

Effect of Selenium-Enriched Substrate on the Chemical Composition, Mineral Bioavailability, and Yield of Edible Mushrooms.

Mushrooms absorb minerals from substrates in which they are cultivated, so they could be used as vehicles of minerals that are deficient in human or animal diets, such as selenium. Selenium deficiency aggravates cardiovascular diseases, diabetes mellitus, and intestinal cancer. This work presents the latest discoveries related to the production of edible mushrooms in selenium-enriched substrates and discusses their use as an alternative to supply the deficiency of this mineral in human and animal diets. Selenized mushrooms and their derived extracts present bioaccessible and bioavailable forms of selenium, as antioxidant and antitumor activity, as demonstrated in various in vitro and in vivo experiments. Consequently, the consumption of these mushrooms reduces the levels of blood cholesterol and glucose. On the other hand, growing mushrooms in selenium-enriched substrates may alter the yield and their chemical composition, and this lack of standardization is still an obstacle to the scale up of the production process. On the other hand, the use of agro-industrial by-products as substrates can enable the cultivation of enriched edible mushrooms and their commercialization.

Effects of environmental factors on microbiota of fruits and soil of Coffea arabica in Brazil.

In recent years, several studies have been developed to understand the impact of fermentation on the final quality of coffee and have indicated that postharvest processing could be a determinant of quality. However, a trend has appeared as a scientific counterpoint, indicating that the interactions between soil, fruit, altitude, and slope exposures with respect to the Sun are important to understand the behavior of the microbiome in coffee. Studies on the microbiota of coffee have addressed its role during the fermentation process, however the knowledge of indigenous microorganisms harbored in fruits and soil of coffee trees growing in fields are essential, as they can contribute to fermentation. Therefore, the aim of this work was to evaluate the influence of topographic and edaphic factors on the bacterial and fungal communities present in the soil and in the fruits of Coffea arabica trees. Samples of fruits and soil were collected from different growing areas at different altitudes and soil conditions. The microbial DNA was extracted and sequenced. The results showed the contribution of environmental factors in the structure of bacterial and fungal communities. The richness, evenness and diversity of the mycobiome and bacteriome were higher in the soil than in the fruits, independent of altitude. In addition, coffee trees at higher altitudes tended to have more bacteria shared between the soil and fruits. The co-occurrence/co-exclusion network showed that bacteria-bacteria connections were greater in higher altitudes. On another hand, fungi-fungi and fungi-bacteria connections were higher in low altitudes. This was the first study that evaluates in deep the influence of environmental factors in the microbiota habiting fruits and soil coffee trees, which may affect the coffee beverage quality.

Agroecological coffee management increases arbuscular mycorrhizal fungi diversity.

Agroecology aims to maintain ecosystem services by minimizing the impact of agriculture and promoting the use of biological potential. Arbuscular mycorrhizal fungi (AMF) are elements which are key to improving crop productivity and soil quality. It is pertinent to understand how agricultural management in the tropics affects the AMF spatio-temporal community composition, especially in crops of global importance, such as coffee (Coffea arabica L.). Soil and root samples were collected from three localities under three management systems (agroecological, conventional and forest fragment), during the phenological stages of coffee (flowering, grain filling, harvesting). Spores were extracted for morphological identification and molecular community analysis by PCR-DGGE. Dendrograms were prepared and the bands were sequenced and analyzed by bioinformatics. No differences were observed in the richness of morphospecies between management systems, localities and period, but little is known about tropical species. Molecular analysis showed that the agroecological management system was similar to natural forest and with a higher diversity indices than conventional management. Locality and period of sample affect AMF community composition. It is necessary to associate classical taxonomic evaluations with molecular biological techniques because different approaches can lead to different outcomes. This study contributes to the understanding of the impact of agriculture management systems on AMF and provides evidence that agroecology is a management system applicable to sustainable coffee production.

Nitrogen-fixing bacteria in Eucalyptus globulus plantations.

Eucalypt cultivation is an important economic activity worldwide. In Portugal, Eucalyptus globulus plantations account for one-third of the total forested area. The nutritional requirements of this crop have been well studied, and nitrogen (N) is one of the most important elements required for vegetal growth. N dynamics in soils are influenced by microorganisms, such as diazotrophic bacteria (DB) that are responsible for biological nitrogen fixation (BNF), so the aim of this study was to evaluate and identity the main groups of DB in E. globulus plantations. Samples of soil and root systems were collected in winter and summer from three different Portuguese regions (Penafiel, Gavião and Odemira). We observed that DB communities were affected by season, N fertilization and moisture. Furthermore Bradyrhizobium and Burkholderia were the most prevalent genera in these three regions. This is the first study describing the dynamic of these bacteria in E. globulus plantations, and these data will likely contribute to a better understanding of the nutritional requirements of eucalypt cultivation and associated organic matter turnover.

Degradation of oxo-biodegradable plastic by Pleurotus ostreatus.

Growing concerns regarding the impact of the accumulation of plastic waste over several decades on the environmental have led to the development of biodegradable plastic. These plastics can be degraded by microorganisms and absorbed by the environment and are therefore gaining public support as a possible alternative to petroleum-derived plastics. Among the developed biodegradable plastics, oxo-biodegradable polymers have been used to produce plastic bags. Exposure of this waste plastic to ultraviolet light (UV) or heat can lead to breakage of the polymer chains in the plastic, and the resulting compounds are easily degraded by microorganisms. However, few studies have characterized the microbial degradation of oxo-biodegradable plastics. In this study, we tested the capability of Pleurotus ostreatus to degrade oxo-biodegradable (D2W) plastic without prior physical treatment, such as exposure to UV or thermal heating. After 45 d of incubation in substrate-containing plastic bags, the oxo-biodegradable plastic, which is commonly used in supermarkets, developed cracks and small holes in the plastic surface as a result of the formation of hydroxyl groups and carbon-oxygen bonds. These alterations may be due to laccase activity. Furthermore, we observed the degradation of the dye found in these bags as well as mushroom formation. Thus, P. ostreatus degrades oxo-biodegradable plastics and produces mushrooms using this plastic as substrate.

Enrichment of mushrooms: an interesting strategy for the acquisition of lithium.

The capability of Pleurotus ostreatus mushroom to accumulate lithium (Li) and the accessibility of this Li compared with lithium carbonate (Li(2)CO(3)), often used as psychiatric medicine, were investigated. Mushrooms were produced on a substrate-based on coffee husk, with different added concentrations of lithium chloride (LiCl). Biological efficiency (BE), the crude protein content, the concentration of Li and other elements present in mushrooms were determined. The sequential extraction and in vitro test were used to verify the accessibility and the degree of solubility of this element. Li concentration in mushrooms was directly influenced by increasing LiCl concentration in the substrate (P<0.05). The BE was not affected by different concentrations of LiCl. Li present in enriched mushrooms showed greater accessibility than in Li(2)CO(3). Therefore, P. ostreatus mushrooms, enriched with lithium can be an alternative source of Li, as well as being a food with high nutritional value.