O feijão-caupi Vigna unguiculata [L.] Walp. é a principal cultura de subsistência do semiárido brasileiro, sendo fonte de proteínas de baixo custo, notadamente, para populações carentes. A produção dessa cultura no Nordeste é baixa devido à não utilização de insumos agrícolas - entre eles, o fertilizante nitrogenado. Por outro lado, bactérias promotoras de crescimento em plantas (BPCPs) vêm sendo estudadas, de forma a maximizar a fixação de N2, disponibilizar nutrientes como P ou fito-hormônios e inibir doenças. Os objetivos deste trabalho foram verificar a viabilidade da coinoculação das sementes de feijão-caupi usando Paenibacillus, Brevibacillus e, ou, Bacillus e Bradyrhizobium-caupi; caracterizar as estirpes quanto à produção de ácido indol acético (AIA) e solubilização de fosfato; e avaliar o sinergismo entre os microrganismos como alternativa para otimizar a FBN. Os experimentos foram conduzidos em laboratório e em casa de vegetação do Instituto Agronômico de Pernambuco (IPA), utilizando o feijão-caupi cv. "IPA - 206". As estirpes utilizadas foram: Bacillus sp. - 449, 450, 451, 461 e ANBE 31; B. cereus - 440; B. subtilis - 438, 441, 454, 455 e 459; B. pumilus - 444, 445 e 448; B. megaterium - 462; Brevibacillus brevis - 447; Paenibacillus brasilensis - 24, 172 e 177; P. graminis - MC 04.21, MC 22.13 e BR 60106; P. polymyxa - S21; e P. durus - RBN4. Os microrganismos não apresentaram capacidade para produzir AIA nem solubilizar fosfato. Ocorreu sinergismo das estirpes de Bacillus sp. (449) e Bacillus pumilus (444) coinoculadas com a estirpe de Bradyrhizobium sp. (BR 3267) no feijão-caupi.

Brazil is one of the largest grain producers worldwide, with yields heavily dependent on ecologically and financially expensive inputs. One possible approach to reduce these inputs is inoculation with plant-growth-promoting bacteria, whose large-scale use depends on a continual search for new genotypes for inoculant production. Several bacteria with potential for this have been isolated from plants that are more adapted to stressful environments. Thus, we aimed to evaluate the potential of pangolão grass (Digitaria eriantha cv. Suvernola) endophytic bacteria both in vitro and on maize growth. To this end, endophytic bacteria were isolated from pangolão grass of a tropical semiarid climate and a random subset of 80 strains was evaluated for biological nitrogen fixation, HCN, IAA and siderophore production and calcium phosphate solubilization, and later for maize growth promotion. All strains were positive for at least one of these in vitro growth promotion mechanisms and some strains increased maize plant height and root length, including some with better results than plants receiving commercial inoculants, confirming the potential of endophytic bacteria from stress-adapted plants. In vitro results had poor correlation with plant growth promotion, which indicates that the common practice of using these laboratory techniques as a pre-selection tool before a subset of strains is evaluated for plant growth promotion might result in the rejection of potentially interesting strains.

Artisanal and Small-Scale Gold Mining (ASGM) is a primary source of global mercury pollution, creating an urgent need for sustainable, low-cost alternatives to amalgamation. This study investigates the use of cassava wastewater (manipueira), a cyanogenic agricultural byproduct, as a lixiviant for a gold concentrate (14.30–15.87 ppm Au) from an artisanal mine. Two approaches were evaluated: direct leaching with manipueira in natura (250 ppm CN⁻) in single and double 8 h and 12 h cycles, and leaching with a cyanide solution concentrated from dilute manipueira (100 ppm CN⁻) via a simplified air-stripping system. Results were benchmarked against the mine’s amalgamation (44.7% recovery) and 30-day heap leach (75.8% recovery) processes. The most effective method observed was a two-cycle, 8 h leach with manipueira in natura, which achieved a mean gold recovery of $76.75\pm 4.71\%$. This result is comparable to the efficiency of the site’s lengthy heap leach process and suggests a promising, faster, route to eliminating mercury use. Longer (12 h) leaching cycles yielded lower recoveries, suggesting process limitations such as preg-robbing. The cyanide concentration method proved inefficient, recovering a maximum of 12.40% of the available cyanide and resulting in a weaker lixiviant. The findings demonstrate that while direct leaching is a viable alternative to mercury, the inherent instability of manipueira necessitates a focus on developing efficient, controlled systems to extract and concentrate its cyanide content, thereby creating a standardized “green” reagent from a large-volume agricultural waste stream.

This study aimed to assess the occurrence of arbuscular mycorrhizal fungi (AMF) in annatto (Bixa orellana L.) cultivars and their response to AMF inoculation using biometric parameters. The occurrence surveys were conducted in annatto fields in three municipalities from Pernambuco Forest Zone: Lagoa de Itaenga, Gloria de Goitá, and Vitoria de Santo Antão, and in four cultivars (Red Piave, Green Piave, Red Peruvian Paulista, and Green Peruvian Paulista). In a greenhouse, biometric parameters of annatto seedlings of Red Piave, Red Peruvian Paulista, Embrapa-36, and Embrapa-37 cultivars inoculated with AMF isolated from annatto fields. The Red Piave cultivar exhibited greater root colonization than the Green Peruvian Paulista in the Lagoa de Itaenga and Vitoria de Santo Antão municipalities. The cultivar Red Piave showed a more beneficial association with AMF in plants and soil than cultivar Green Peruvian Paulista did, in both Lagoa de Itaenga and Vitoria de Santo Antão. AMF inoculation was effective in promoting the growth of annatto plants, particularly those inoculants with S. heterogama and C. etunicatum.