No abstract

The cocoa and palm oil agro-industries active in the state of Bahia, Brazil, generate high quantities of lignocellulosic wastes that could be recycled through their use in the formulation of substrates to cultivate edible mushrooms. Pleurotus ostreatus, also known as oyster mushroom, is the second most cultivated mushroom in the world due to its highly appreciated gastronomic, nutritional, and medicinal characteristics. This work evaluated the vertical mycelium growth, biological efficiency, mushroom yield, and nutritional composition of P. ostreatus produced in substrates formulated with a combination of palm oil fruit mesocarp (POFM) and cocoa almond peels (CAP) processing wastes. The substrates were formulated with the following POFM/CAP proportions (%/%): S1 – 86.4/9.6; S2 – 76.8/19.2; S3 – 67.2/28.8; S4 – 57.6/38.4, and S5 – 48.0/48.0. Substrates also received 3% powdered charcoal and 1% calcium carbonate. Substrates S1, S2, S3, and S4 were superior for vertical mycelium growth. S2 promoted the best biological efficiency (148.8%) and yield (560.5g·kg-1).The mushrooms produced in all substrates presented good nutritional values, although mushrooms produced using the S2 presented the highest crude protein content. Overall, S1 is the recommended substrate as it results in higher yields of nutrient rich mushrooms. Production of P. ostreatus in substrates composed of POFM and CAP represents a good alternative for recycling these wastes with potential economic and ecological benefits to regions where palm oil and cocoa are grown.

Agave sisalana, known as sisal, yields the world’s main natural stiff fiber used to produce various industrial products. The Brazilian semiarid is the largest sisal producing region in the world; however, production is under threat by sisal bole rot disease, caused by Aspergillus welwitschiae. Since chemical control of this disease is questionable in drought-ridden areas with little investment in crop management and due to environmental and public health concerns, the search for a biocontrol agent against A. welwitschiae is warranted. In this work, we isolated and identificated Penicillium citrinum as an endophyte from sisal plants collected from the Brazilian semi-arid and investigated whether it could be a biocontrol agent against sisal bole rot. P. citrinum inhibited the mycelium growth of A. welwitschiae by 65.8% when inoculated 72 hours before the pathogen, in dual culture medium assays. We found that P. citrinum can reduce sisal bole rot disease up to 90% when inoculated in sisal plants 48 hours before pathogen inoculation. Altogether, our data suggest a potential role for P. citrinum in the control of sisal bole rot disease.

The aim of this study was to isolate, quantify, identify and characterize the culturable diazotrophic bacterial community associated with sisal (Agave sisalana P.) and assess its potential for plant growth promotion and tolerance to abiotic stress. Nitrogen-free Burk's medium was used for bacteria isolation and quantification. Isolates carrying the nifH gene were typed by BOX-PCR and sequenced for the 16S rRNA region. Additionally, the bacteria was tested for growth promotion in maize plants and for salinity tolerance in cucumber seedlings. The representative isolates were identified as members of Pantoea, Rhizobium, Burkholderia, Leifsonia and Bacillus genera. All isolates were positive for at least two of the nine plant growth promoting (PGP) traits tested. All isolates showed positive traits for tolerance to abiotic stress. Leifsonia sp. (S1.5) significantly increased root length, stem length and total fresh matter, and it was involved in the reduction of deleterious salt effects (60 mM NaCl) in cucumber seedlings. Diazotrophic bacterial community associated with sisal plants is genetically diverse, exhibits several plant growth-promoting traits and shows potential to support plant growth in adverse environments (salinity).

Cultura com importante papel socioeconômico para o semiárido nordestino, o Sisal (Agave sisalana Perrine) concentra sua produção no Brasil principalmente no estado da Bahia. Nas últimas décadas, tem ocorrido um decréscimo na produtividade de sisal devido à ocorrência da doença podridão vermelha causada pelo fungo Aspergillus welwitschiae. Objetivou-se no presente trabalho avaliar o potencial do resíduo oriundo do desfibramento das folhas de sisal, fermentado em condições naturais de campo, para o controle de A. welwitschiae e da podridão vermelha, por meio de testes in vitro, em segmentos de caule de sisal e em mudas de sisal. O patógeno foi isolado de plantas de sisal com sintomas da doença de uma área de produção de sisal no município de São Domingos – BA, foi avaliado o potencial de inibição do crescimento micelial e esporulação de A. welwitschiae em meio de cultura BDA contendo a calda nas concentrações de 0%, 25%, 50% e 75%, e em segmentos do caule do sisal e mudas a calda foi avaliada nas concentrações 0, 25, 50, 75 e 100%. A calda do resíduo líquido do desfibramento das folhas de sisal causou inibição do crescimento micelial do A. welwitschiae de 89,8% e 100% nas concentrações de 50% e 75%. Em disco de caule de sisal a calda promoveu o controle da esporulação do A. welwitschiae nas concentrações de 25%, 50%, 75% e 100%. Em mudas de sisal, a calda reduziu a severidade da doença, mas não promoveu o controle de 100% da doença. A calda do resíduo fermentado de sisal tem efeito tóxico ao patógeno em função do aumento da concentração, atuando no controle de A. welwitschiae e reduz a severidade da podridão vermelha em mudas de sisal.