Abstract Beta-1,3-glucanases are enzymes that hydrolyze beta-1,3-glucans, and they are essential for the metabolism of seaweed, plants and fungi. These enzymes also participate in the digestion of herbivore and fungivore animals. Because of the importance of these enzymes in insects, beta-1,3-glucanase inhibitors may be used for the development of new control strategies against agricultural pests and disease vectors. Beta-1,3-glucanase inhibitors have been described in the brown seaweed Laminaria cichorioides, but were never recorded in Brazilian seaweed species. We evaluated the presence of beta-1,3-glucanase inhibitors in samples of Padina gymnospora, Dictyota sp., Colpomenia sinuosa, and Lobophora sp., collected in Arraial d’Ajuda (Bahia). Ethanolic or buffer extracts were used in inhibition tests against the beta-1,3-glucanase of Trichoderma sp. Extracts in buffer showed no inhibition, but ethanolic extracts from all species showed different extents of inhibition. Samples from Dictyota sp. and P. gymnospora showed inhibitions above 75% (absolute ethanol) or 50% (ethanol 50%). In summary, extraction with absolute ethanol resulted in better inhibitions, and P. gymnospora showed the higher inhibitions. Brazilian seaweed may be good sources of beta-1,3-glucanase inhibitors for biochemical and physiological studies of these enzymes. Besides that, these molecules show potential for the development of new biotechnological tools for insect control.

Gracilaria cornea J. Agardh é uma importante agarófita que ocorre no Oeste do Oceano Atlântico. Indivíduos de coloração verde de G. cornea foram encontrados em uma população natural, próximos a indivíduos de coloração vermelha, mais comuns. Devido à importância de linhagens cromáticas em estudos de genética e variabilidade intraespecífica, o objetivo deste trabalho foi caracterizar as linhagens verde e vermelha avaliando diferentes condições de nutrintes e luz. Gametófitos verdes e vermelhos foram cultivados em fotoperíodo de 14 horas (14L:10E), com períodos alternados de aeração de 30 minutos. Duas soluções de água do mar enriquecida foram testadas: von Stosch (VSS) nas concentrações reduzidas a 12,5% e 25%; e Provasoli (PES) nas concentrações reduzidas de 25% e 50%, e 100%. A irradiância foi de 45 mimol fótons m-2 s-1. Num outro experimento, utilizando-se PES 100%, dois tipos de fontes luminosas (lâmpadas fluorescentes Osram 40 W luz do dia e Sylvania Designer 3.500) foram testadas em duas irradiâncias: 90 e 180 mimol fótons m-2 s-1. As taxas de crescimento (TC) foram avaliadas durante cinco semanas. Todas as condições testadas não promoveram a diferenciação de estruturas reprodutivas e poucas ramificações foram formadas nos gametófitos vermelhos e verdes. As linhagens selvagem e verde apresentaram TC semelhantes, que foram maiores em VSS 12,5% (8,4% dia-1) do que em VSS 25% (7,1% dia-1), sugerindo uma adaptação da espécie a baixas concentrações de nutrientes. As taxas de crescimento foram maiores em 180 (9,0% dia-1) do que em 90 mimol fótons m-2 s-1 (6,3% dia-1). Sugere-se que G. cornea seja cultivada em altas irradiâncias e baixas concentrações de nutrientes. Esses resultados devem ser considerados em futuros estudos genéticos e fisiológicos da espécie.

Gracilaria cornea J. Agardh is an important agarophyte occurring in the western Atlantic Ocean. Green colour individuals of G. cornea were found in a natural population, growing next to red individuals, which were more common. Due to the importance of colour strains in genetic and intraspecific variability studies, this work aimed to characterize the red and green strains evaluating different nutritional and light conditions. Red and green gametophytes were cultivated at 14:10 light: dark cycle, with alternating aeration periods of 30 min. Two different enriched solutions were tested: von Stosch (VSS) at concentrations reduced to 12.5% and 25%; and Provasoli (PES) at concentrations reduced to 25% and 50%, and 100%. Red and green gametophytes were cultivated at the irradiance of 45 mumol photons m-2 s-1. In another experiment utilizing PES 100%, two sources of light (Osram 40 W daylight fluorescent tubes and Sylvania Designer 3,500 tubes) were tested at irradiances of 90 and 180 mumol photons m-2 s-1. Growth rates (GR) were evaluated for five weeks. Gametophytes developed few branches and reproductive structures were not induced. Differences were not observed between GR of red and green strains in the conditions tested. GR were higher in VSS 12.5% (8.4% day-1) than in 25% (7.1% day-1), suggesting an adaptation of the species to low nutrient concentrations. GR were higher at 180 (9.0% day-1) than at 90 mumol photons m-2 s-1 (6.3% day-1). These results suggest that G. cornea should be cultivated in laboratory at high irradiances and low nutrient concentrations. These data will be useful in future genetic and physiological studies of the species.