Thaís Marcelo Souza

The growing demand for environmentally responsible lubricants motivates the use of bio-based base stocks and benign solid additives. This study assesses the tribological performance of two Amazonian vegetable oils, Carapa guianensis (andiroba) and Copaifera spp. (copaiba resin) and a paraffinic mineral oil (PNL30) formulated with different zinc oxide (ZnO) particles, namely nanocrystals and microcrystals, at 0.01, 0.05, and 0.10 wt.%. Reciprocating sliding tests, coupled with 3D profilometry, viscosity, and sedimentation analyses, were used to link dispersion stability with friction and wear responses. A preliminary stability screening constrained the practical loading window to ≤0.10 wt.% for reproducible suspensions. Performance depended on the interplay between particle type and base-oil chemistry. Andiroba exhibited the most pronounced gains, with ZnO microcrystals near 0.05 wt.% delivering the best friction outcomes and the largest wear reductions (up to ~35%). In copaiba resin oil, nanocrystals produced small, sometimes non-significant improvements, whereas microcrystals tended to worsen wear consistent with abrasive third-body effects in a less polar matrix. In PNL30, the overall benefits were modest: nanocrystal additions generally increased wear, whereas microcrystals particularly at the highest loading 0.10 wt.% achieved a 36.4% reduction in SWR, representing a measurable and statistically significant improvement in wear resistance. These results highlight that eco-efficient lubricant design should co-optimize particle characteristics and dosage with base-oil polarity and film-forming tendencies, prioritizing dispersion stability alongside tribological targets.

The rhizosphere of cacao trees harbors a diverse microbial community, the composition of which can be influenced by factors such as plant genotype and seasonal variations. This study aimed to isolate and identify ascomycete fungi associated with the rhizosphere of cacao trees cultivated under cabruca agroforestry systems. Soil samples were collected from three municipalities Camacan, Ilhéus and Uruçuca during two distinct climatic periods: the rainy season (June 2023) and the dry season (November 2023). The samples underwent serial dilution (10⁻² and 10⁻³), baiting with plant materials (sweet potato, carrot, and castor bean leaf), and soil-plate techniques. The serial dilution method yielded 930 fungal colonies, with 392 colonies at the 10⁻² dilution and 543 at the 10⁻³ dilution. The plant baiting technique resulted in 196 fungal cultures, comprising 67 colonies recovered during the rainy season and 129 during the dry season. The soil-plate method facilitated the recovery of 201 colonies, with 90 from the first collection and 111 from the second. The genus Trichoderma was observed across all treatments and sampling periods, associated with all cacao genotypes examined. Fungal isolates were identified based on morphological analysis of their reproductive structures. In total, 1,329 fungal colonies were obtained from the rhizospheric samples, representing significant ascomycete diversity. Notable genera identified included Aspergillus, Chaetomium, Cladosporium, Fusarium, Lasiodiplodia, Penicillium, Pestalotiopsis and Trichoderma, as well as members of the family Nectriaceae. The data indicated a higher incidence of fungal isolates during the dry season, suggesting that seasonal variation influences the rhizospheric fungal community.

Aiming to expand the knowledge about the occurrence of endophytic fungi associated with cocoa (Theobroma cacao), a study was carried out at the Univesidade Estadual de Santa Cruz (UESC), Ilhéus, Bahia State, during the period from August 2019 to May 2021. Two hundred and seventy isolates were obtained from fragments of leaves and branches collected in the field, considering the rainy and dry periods, and 137 were identified, belonging to nine taxas distributed in nine different families of the Phylum Ascomycota. Selected isolates of Chaetomium globosum, Colletotrichum, Fusarium oxysporum, Neopestalotiopsis and Xylaria were inoculated into seminal seedlings of three cacao varieties under greenhouse conditions, and reisolation was carried out after 60 days. Of the inoculated isolates, all were recovered. Chaetomium globosum and Fusarium oxysporum were most reisolated from the inoculated seedlings, and the first was even present in the non-inoculated seedlings (control), indicating the need to undertake studies that aim to better understand the association of this fungus with the cacao tree, since it was characterized its vertical transmission. The evaluation of the biological control potential of some endophytes found in this study may bring new perspectives for the integrated management of cacao diseases, mainly Witch's Broom (Moniliophthora perniciosa) and Brown Rot (Phytophthora spp.).

In June 2022, anthracnose was detected on the leaves of Annona muricata L. (soursop) in Ibirapitanga, Bahia, Brazil. To identify the pathogens, diseased leaves were surface sterilized and cultured on potato dextrose agar, resulting in the selection of two isolates, IBIRA-P5R2 and IBIRA-P2F1R2, which were used for further analysis. IBIRA-P5R2 exhibited gray to white mycelium with dark conidiomata, cylindrical conidia, and dark appressoria. In contrast, IBIRA-P2F1R2 exhibited dense, pale gray mycelium with distinct conidial and ascospore characteristics. Genetic analysis involved sequencing three regions: Internal Transcribed Spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and actin (ACT), with results deposited in GenBank. BLAST analysis revealed that IBIRA-P5R2’s sequences were 95.45% similar to Colletotrichum karstii, while IBIRA-P2F1R2’s sequences were 99.06% identical to . Colletotrichum fructicolaPathogenicity tests confirmed that both isolates caused anthracnose symptoms in soursop seedlings, with dark spots developing on leaves after three days. The pathogens were reisolated from infected leaves, confirming the same cultural and morphological traits as the original isolates. This study marks the firstrecorded occurrence of C. karstii and C. fructicola causing anthracnose on soursop in Bahia, Brazil. The findings aim to inform soursop farmers about this emerging disease, highlighting the need for tailored integrated management strategies to address different plant pathogens effectively.

The present study brings the first report of species of Chaetomium and Humicola from Bahia state. Chaetomium globosum was isolated from different substrates of cacao, jackfruit, papaya and soursop and C. pseudoglobosum from cow dung. Humicola cuyabenoensis was isolated from soil samples of cacao plantations in the southeast Bahia.

Cariniana legalis (Mart.) Kuntze (Lecythidaceae), commonly known as “Jequitibá Rosa,” an endemic tree from Brazil, is one of the largest trees that grows in the Atlantic Rain Forest. Jequitibá Rosa...

Os objetivos foram descrever e ilustrar morfologicamente frutos, sementes e plântulas de Senegalia bahiensis, além de suas biometrias. Os frutos foram colhidos em árvores-matrizes no município de Castro Alves - BA - Brasil. As avaliações e observações foram feitas mediante uma amostragem aleatória de 100 frutos de cada matriz. Para o fruto avaliaram-se: tipo; cor; comprimento, largura, textura, número de sementes sadias e bem formadas por fruto e número de falsos septos. Sendo o comprimento mensurado com régua milimetrada e a largura foi medido com o auxílio de um paquímetro digital de precisão0,1 mm. As características biométricas e morfológicas das sementes observadas foram: cor, dimensão, forma, hilo, calaza, tegumento e embrião. O acompanhamento do desenvolvimento das plântulas foi realizado em casa de vegetação com sombrite 50%. Foi realizada a descrição das partes das plântulas, como: raiz, coleto, cotilédones hipocótilo, epicótilo, tipo de germinação, primeiro par de eófilos, além da tomada de comprimento da raiz primária, comprimento do hipocótilo e do epicótilo com auxílio de uma régua milimetrada. Os dados biométricos foram submetidos à análise descritiva calculando-se a média, máximo e mínimo, coeficiente de variação e erro padrão da média. Características dos frutos como sua deiscência, forma, coloração e sua textura; das sementes, como presença de pleurograma, calaza e posição do embrião; das plântulas como presença de estípulas interpeciolar e da filotaxia dos folíolulos, constituem-se como elementos que auxiliam para identificação da espécie no viveiro e em laboratório, como também no campo em trabalhos de regeneração natural.