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Bacterial endophytes (120) were isolated from six halophytes (Distichlis spicata, Cynodon dactylon, Eragrostis obtusiflora, Suaeda torreyana, Kochia scoparia, and Baccharis salicifolia). These halophiles were molecularly identified and characterized with or without NaCl conditions. Characterization was based on tests such as indole acetic acid (IAA), exopolysaccharides (EPS), and siderophores (SID) production; solubilization of phosphate (P), potassium (K), zinc (Zn), and manganese (Mn); mineralization of phytate; enzymatic activity (acid and alkaline phosphatase, phytases, xylanases, and chitinases) and the mineralization/solubilization mechanisms involved (organic acids and sugars). Moreover, compatibility among bacteria was assessed. Eleven halophiles were characterized as highly tolerant to NaCl (2.5 M). The bacteria isolated were all different from each other. Two belonged to Bacillus velezensis and one to B. pumilus while the rest of bacteria were identified up to the genus level as belonging to Bacillus, Halobacillus, Halomonas, Pseudomonas, Nesterenkonia, and three strains of Oceanobacillus. The biochemical responses of nutrient solubilization and enzymatic activity were different between bacteria and were influenced by the presence of NaCl. Organic acids were involved in P mineralization and nutrient solubilization. Tartaric acid was common in the solubilization of P, Zn, and K. Maleic and vanillic acid were only detected in Zn and K solubilization, respectively. Furthermore, sugars appeared to be involved in the solubilization of nutrients; fructose was detected in the solubilization tests. Therefore, these biochemical bacterial characteristics should be corroborated in vivo and tested as a consortium to mitigate saline stress in glycophytes under a global climate change scheme that threatens to exacerbate soil salinity. [ABSTRACT FROM AUTHOR]

To mitigate the trace elements (TE) dispersion in acid mine drainage (AMD), laboratory experiments were carried out comparing nine agricultural by-products. Five adsorbent materials were selected for adsorption batch experiments. Then, the biosorbents were tested to remove TE from AMD collected from oxidized tailings heaps, using equilibrium experiments. The As adsorption on carbonatite was high (15.4 g kg−1); Cd (4.1 g kg−1) on cow manure; Cu (17.9 g kg−1) on carbonatite; Pb (14.1 g kg−1), and Zn (16.4 g kg−1) on rabbit manure. The Zn adsorption on oat straw and carbonatite was well fit by Freundlich isotherm. The Langmuir equation mimics well Zn and Cd adsorption by peat moss and caw manure; Cu adsorption on peat moss and vermicompost. Except for vermicompost and carbonatite, the adsorption improved as the buffer capacity of the biosorbents increased, following a second-order equation. The FTIR analysis showed that the carboxylic, aromatic, and aliphatic aldehyde groups were involved in TE adsorption. Soluble-As, -Cd, -Cu, and -Zn from AMD were removed (90%) by the addition of 4 and 8% (m/v) of sheep manure, cow manure, rabbit manure, vermicompost, and carbonatite. Lead concentration in AMD was increased due to the addition of the biosorbents. [ABSTRACT FROM AUTHOR]

Social Impact Statement: Vanilla planifolia is the source of the spice vanilla. This study is part of an international initiative to study the biology, including mycorrhizal fungi and cultivation practices of vanilla to improve its production in Mexico. The study focused on documenting mycorrhizal fungal diversity in vanilla. It also provided preliminary data on differences in mycorrhizal fungal communities associated with cultivation practices. A richer mycorrhizal community was observed in vanilla growing in a wild natural farm compared with those from a highly managed farm. Our research provides insights for sustainable vanilla production that can benefit Mexican farming communities. Summary: Relatively little is known regarding differences in root symbionts (i.e., mycorrhizae) between epiphytic and terrestrial orchids. We characterized the mycorrhizal fungal communities of aerial and terrestrial roots of the orchid, Vanilla planifolia, from four Mexican farms representing different management systems.Amplicon sequencing identified 40 putative mycorrhizal fungi based on ITS sequence data, these included traditional orchid mycorrhizal fungi such as Ceratobasidium, and Thanatephorus in the order Cantharellales as well as Serendipitaceae in the order Sebacinales, and species of several genera traditionally considered as ectomycorrhizal fungi. Mycorrhizal fungal communities were similar in aerial and terrestrial roots, but differed in read abundances.Plants growing in wild‐natural conditions hosted a richer, but not statistically different, community of mycorrhizal fungi in comparison with plants in the highly managed farm. Soil characteristics including texture, organic matter, N, P, and K do not explain differences between fungal communities at these farms.This is one of the first reports of a diverse community of fungi traditionally considered to form ectomycorrhizas in association with aerial orchid roots. Further research is needed to understand the functional role of these putative mycorrhizal fungi in the ecology of V. planifolia, and if ectomycorrhizal fungi commonly occur in other hemiepiphytic and epiphytic orchids. [ABSTRACT FROM AUTHOR]

A soil and plant survey was carried out in a tailing heap afforested 30 years ago to gain information about the changes in the tailing and metal uptake by plants. A poor development of Technosol was found. It was observed accumulation of OM spatio temporarily. Metal concentrations in the soil profile varied between plots. Extractable Pb concentrations ranged from 0.4 to 2.9%; extractable Cd varied 9.7–46% of the total concentration. PCA analysis shows DTPA-Zn and DTPA-Cu, Na, K, and OM have the widest concentrations range between soil layers. Casuarina equisetifolia and Pennisetum clandestinum formed a pristine uniform litter layer, whereas Eucalyptus camaldulensis did not form a litter layer. Casuarina equisetifolia has a higher population density (756 p ha−1) compared to Populus nigra (528 p ha−1) and E. camaldulensis (621 p ha−1). Pennisetum clandestinum grew successfully and covered the tailing, but Cd and Pb concentrations were above the domestic animal toxicity limits, 0.5 and 10 mg kg−1, respectively. Populus nigra absorbed more Zn than Casuarina equisetifolia and Eucalyptus camaldulensis. Trees species did not accumulate high foliar Cu and Zn concentrations, but Pb (47.7–124.3 mg kg−1) and Cd (5.7–26.8 mg kg−1) concentrations are over those reported for mature leaf tissues. Pennisetum clandestinum formed soil cover on remediated plots. Casuarina equisetifolia was efficient in forming a litter soil horizon. Trasdescantia fluminensis accumulated Pb. Populus nigra accumulated Zn and Cd from the tailing heap. [ABSTRACT FROM AUTHOR]

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