RESUMO
Among the prospective biocontrol agents, the saprophytic filamentous fungus Clonostachys rosea is an excellent necrotrophic mycoparasite of numerous plant pathogenic fungi. However, its commercial development has been hampered by mass production difficulties during solid-state fermentation. Conversely, the submerged liquid fermentation shortens the cultivation time while increasing yields of fungal propagules. However, this method has been overlooked for C. rosea. In this work, we investigated the impact of liquid pre-culture inoculum on the spore production by the two-stage fermentation process using rice grains in comparison to the traditional solid-state fermentation. In parallel, we studied the submerged cultivation of C. rosea by manipulating carbon-to-nitrogen (C:N) ratio and nitrogen source, with the further optimization of spore production in a benchtop bioreactor. Additional bioassays included assessing the bioactivity of water-dispersible microgranules (that contained a submerged conidia) against the whitefly (Bemisia tabaci biotype B) and Sclerotinia sclerotiorum (causal agent of the white mold). Our results showed a maximum concentration of 1.1 × 109 conidia/g-dry-matter after 7 days of cultivation by two-stage fermentation process. The liquid fermentation yielded 1.4 × 109 submerged conidia/ml after 7 days using a medium with a 50:1 C:N ratio, and it also induced the production of microsclerotia (MS) up to 1.35 × 104/ml within 6 days with 10:1 C:N ratio; both media were supplemented with dextrose monohydrate and soybean meal. The fermentation batches carried out in a benchtop bioreactor with medium 50:1 C:N ratio and amended with soybean meal rendered a production peak on the fourth day, corresponding to 1.11 × 109 conidia/ml and 4.35 × 108 colony forming units (CFU)/ml. Following air-drying, the conidia production from air-dried microgranules of C. rosea biomass was estimated at 3.4 × 1010 conidia/g of formulated product upon re-hydration for 7 days. Both submerged conidia and MS of C. rosea inhibited 100% germination of S. sclerotiorum sclerotia by direct parasitism. The air-dried submerged conidia exhibited a suppressive activity on sclerotia (88% mycoparasitism) and early whitefly nymphs (76.2% mortality) that rendered LC50 values of 3.2 × 104 CFU/g soil and 1.5 × 107 CFU/ml, respectively. Therefore, the submerged liquid culture of C. rosea may offer a feasible and cost-effective method for its large-scale production, alleviating critical constraints to their commercial use while providing an additional tool for management of B. tabaci and S. sclerotiorum.
RESUMO
The extract of the Kappaphycus alvarezii seaweed is used as a leaf biofertilizer and several studies had proven its efficiency in several crops. This study aimed to analyze the economic viability of fresh seaweed production and the chemically characterized seaweed extract cultivated as a technical-economic alternative for coastal communities. Yields of the solid and liquid fractions were quantified, the extract was characterized in its chemical composition of macronutrients and micronutrients and it was classified according to the criteria of the Brazilian legislation of agricultural fertilizers. For the study of economic feasibility, different sales price scenarios were considered and compared with the commercialization of fresh seaweed. The average yield obtained from the processing of the Brazilian adapted strains of the K. alvarezii for the liquid fraction or fresh seaweed extract was 0.71 ± 0.0080 L kg-1 and the moisture solid production was 295 ± 0.0126 g kg-1. The production of fresh seaweed was unfeasible and for the handmade extract was economically viable for the scenario with the sale price of US$ 2.77 with a net present value of US$ 35,300.13 and an internal rate of return (IRR) of 38.99% over ten year.
O extrato da alga marinha Kappaphycus alvarezii é utilizado como biofertilizante foliar e vários estudos comprovaram sua eficiência agronômica em diversas culturas agrícolas. Este estudo teve como objetivo analisar a viabilidade econômica do cultivo de algas marinhas frescas e seu extrato quimicamente caracterizado como alternativa técnico-econômica para comunidades costeiras. Os rendimentos das frações sólida e líquida foram quantificados, o extrato foi caracterizado em sua composição química de macronutrientes e micronutrientes e foi classificado de acordo com os critérios da legislação brasileira de fertilizantes agrícolas. Para o estudo de viabilidade econômica, diferentes cenários de preços de venda foram considerados e comparados com a comercialização das algas marinhas frescas. O rendimento médio obtido pelo processamento das linhagens brasileiras de K. alvarezii para a fração líquida ou extrato de alga marinha fresca foi de 0,71 ± 0,0080 L kg-1 e o rendimento da fração sólida foi de 295 ± 0,0126 g kg-1. A produção de algas marinhas frescas foi inviável economicamente e, para o extrato artesanal, foi viável para o cenário com preço de venda de US$ 2,77, com valor presente líquido de US$ 35.300,13 e taxa interna de retorno (TIR) de 38,99% para um horizonte de dez anos.
Assuntos
Alga Marinha , Custos e Análise de Custo , FertilizantesRESUMO
The extract of the Kappaphycus alvarezii seaweed is used as a leaf biofertilizer and several studies had proven its efficiency in several crops. This study aimed to analyze the economic viability of fresh seaweed production and the chemically characterized seaweed extract cultivated as a technical-economic alternative for coastal communities. Yields of the solid and liquid fractions were quantified, the extract was characterized in its chemical composition of macronutrients and micronutrients and it was classified according to the criteria of the Brazilian legislation of agricultural fertilizers. For the study of economic feasibility, different sales price scenarios were considered and compared with the commercialization of fresh seaweed. The average yield obtained from the processing of the Brazilian adapted strains of the K. alvarezii for the liquid fraction or fresh seaweed extract was 0.71 ± 0.0080 L kg-1 and the moisture solid production was 295 ± 0.0126 g kg-1. The production of fresh seaweed was unfeasible and for the handmade extract was economically viable for the scenario with the sale price of US$ 2.77 with a net present value of US$ 35,300.13 and an internal rate of return (IRR) of 38.99% over ten year.(AU)
O extrato da alga marinha Kappaphycus alvarezii é utilizado como biofertilizante foliar e vários estudos comprovaram sua eficiência agronômica em diversas culturas agrícolas. Este estudo teve como objetivo analisar a viabilidade econômica do cultivo de algas marinhas frescas e seu extrato quimicamente caracterizado como alternativa técnico-econômica para comunidades costeiras. Os rendimentos das frações sólida e líquida foram quantificados, o extrato foi caracterizado em sua composição química de macronutrientes e micronutrientes e foi classificado de acordo com os critérios da legislação brasileira de fertilizantes agrícolas. Para o estudo de viabilidade econômica, diferentes cenários de preços de venda foram considerados e comparados com a comercialização das algas marinhas frescas. O rendimento médio obtido pelo processamento das linhagens brasileiras de K. alvarezii para a fração líquida ou extrato de alga marinha fresca foi de 0,71 ± 0,0080 L kg-1 e o rendimento da fração sólida foi de 295 ± 0,0126 g kg-1. A produção de algas marinhas frescas foi inviável economicamente e, para o extrato artesanal, foi viável para o cenário com preço de venda de US$ 2,77, com valor presente líquido de US$ 35.300,13 e taxa interna de retorno (TIR) de 38,99% para um horizonte de dez anos.(AU)