A bacia amazônica tem mais de seis milhões de quilômetros quadrados e abriga a maior floresta tropical do mundo, sendo particularmente importante pela sua biodiversidade e pelo seu papel na ciclagem de água e carbono. Fotossíntese, condutância estomática e fluxo de seiva de espécies florestais da Amazônia apresentam variação ao longo do dia seguindo a variação diurna observada na irradiância, temperatura e o déficit de pressão de vapor. Em decorrência da fotorrespiração, cerca de 25% do carbono fixado é retornado para a atmosfera. Os aumentos na concentração de CO2 na atmosfera previstos para as próximas décadas poderão apresentar efeito positivo na assimilação de carbono deste ecossistema florestal. Em comparação à época chuvosa, redução da umidade do solo e aumento no déficit de pressão de vapor (associado à baixa umidade do ar e alta temperatura) favorecem o fechamento dos estômatos em detrimento da fotossíntese. Desse modo, em comparação com a estação chuvosa, a fotossíntese líquida é menor no período seco. No geral, na Amazônia as árvores que atingem o dossel da floresta crescem a taxas maiores na época chuvosa. Exceto em anos de menor precipitação, o ecossistema florestal atua como sumidouro de carbono na época chuvosa. Mais estudos são necessários para determinar como e de que forma fatores específicos do ambiente físico influenciam a assimilação de carbono e o crescimento de árvores nos diversos grupos funcionais na Amazônia.

One of the most expensive steps in mushroom production is the disinfection of the substrate. This study aimed to evaluate different methods of disinfecting various substrates used in the cultivation of Pleurotus ostreatus from the Amazon. P. ostreatus was grown under uncontrolled temperature conditions in a greenhouse (at approximately 30 °C) on substrates formulated with residues (seeds) of açaí and tucumã palm trees, Brazil nuts shell and pine sawdust. The different substrate disinfection treatments comprised autoclaving, immersion in hot water or immersion in calcium hydroxide (2%). The chemical composition of residues, substrates, and mushrooms was analyzed. During cultivation, it was found that in the treatment with hot water, all the bags were contaminated, and treatment with calcium hydroxide inhibited the colonization and growth of the mushrooms. P. ostreatus grown on the autoclaved açaí substrate supplemented with tucumã had higher production. The highest percentage of fiber content was obtained when the mushrooms were cultivated in the pine substrate supplemented with Brazil nuts (32.68 to 33.65%), and the highest protein content (20.03 to 20.88%) was found in the mushrooms grown on açaí-based substrates. Considering that P. ostreatus showed higher productivity in autoclaved substrates, further studies should be performed to develop alternative methods of disinfecting substrates for the cultivation of mushrooms in the Amazon region, as well as, in other regions with a tropical climate. However, the cultivation of this mushroom is promising using some regional substrates, especially with açaí, which is one of the important natural products of the Amazon.

RESUMOLight and soil water availability may limit carbon uptake of trees in tropical rainforests. The objective of this work was to determine how photosynthetic traits of juvenile trees respond to variations in rainfall seasonality, leaf nutrient content, and opening of the forest canopy. The correlation between leaf nutrient content and annual growth rate of saplings was also assessed. In a terra firme rainforest of the central Amazon, leaf nutrient content and gas exchange parameters were measured in five sapling tree species in the dry and rainy season of 2008. Sapling growth was measured in 2008 and 2009. Rainfall seasonality led to variations in soil water content, but it did not affect leaf gas exchange parameters. Subtle changes in the canopy opening affected CO 2 saturated photosynthesis (A pot , p = 0.04). Although A pot was affected by leaf nutrient content (as follows: P > Mg > Ca > N > K), the relative growth rate of saplings correlated solely with leaf P content (r = 0.52, p = 0.003). At present, reduction in soil water content during the dry season does not seem to be strong enough to cause any effect on photosynthesis of saplings in central Amazonia. This study shows that leaf P content is positively correlated with sapling growth in the central Amazon. Therefore, the positive effect of atmospheric CO 2 fertilization on long-term tree growth will depend on the ability of trees to absorb additional amount of P.Key words: canopy opening, mineral nutrition, potential nutrient use efficiency, rainfall seasonality. O crescimento de arvoretas correlaciona-se com a fotossíntese e teor de fósforo foliar na Amazônia central A disponibilidade de luz e o conteúdo de água do solo podem limitar a fixação de carbono de árvores em florestas tropicais. O objetivo deste trabalho foi determinar como as características fotossintéticas de árvores juvenis (arvoretas) respondem às variações na sazonalidade das chuvas, teor de nutrientes da folha e a abertura do dossel da floresta. Avaliou-se também a correlação entre o crescimento anual das arvoretas e o teor de nutrientes na folha. Parâmetros de trocas gasosas e teor foliar de nutrientes foram mensurados, na estação seca e chuvosa de 2008, em cinco espécies de árvores numa floresta de terra-firme na Amazônia central. O crescimento anual das arvoretas foi mensurado em 2008 e 2009. A sazonalidade das chuvas causou variações na umidade do solo, mas não afetou os parâmetros de trocas gasosas. Mudanças sutis na abertura de dossel afetaram a fotossíntese saturada por CO 2 (A pot , p = 0.04). Embora A pot tenha sido afetado pelos teores de nutrientes da folha (nesta ordem: P > Mg > Ca > N > K), a taxa de crescimento relativo das arvoretas correlacionou-se apenas com o conteúdo de P foliar (r = 0.52, p = 176 Ricardo Antonio Marenco et al. Ricardo Antonio

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Trichoderma reesei is a fungus that has been widely explored for its potential as cellulolytic enzyme producer and has diverse industrial applications. However, obtaining the enzymes is still considered a costly and, sometimes, inefficient process. This study aimed to produce endoglucanases by cultivating T. reesei (CCT-2768) in solid state fermentation, using cashew apple bagasse (CAB), sugarcane bagasse (SCB) and green coconut fiber (GCF) residues as substrates. The influence of moisture and pH on enzyme production was evaluated using a factorial design. T. reesei showed viability for producing endoglucanases in all of the three lignocellulosic residues tested, with maximum activity (2.29 ± 0.01 U/g) observed when cultivated in the SCB substrate and using moisture of 60% and pH 5.5. Thus, use of lignocellulosic residues proves to be a viable alternative for producing endoglucanases by cultivation of Trichoderma reesei, which contributes to the recycling of waste and the reduction of environmental impacts.

Agro-industrial byproducts possess biotechnological potential due to the presence of bioactive compounds. These have positive metabolic effects, such as the reduction of the risk of chronic diseases, inflammation, among others. The cashew apple is one of these byproducts and stands out for its levels of phenolic compounds, flavonoids and ascorbic acid, which provide high antioxidant capacity, in addition to being an excellent source of pectin, a dietary fiber that stimulates the growth of bifidobacteria. The aim of this study was to evaluate the bioactive characteristics and the in vitro prebiotic effect of processed cashew apple when subjected to Bifidobacterium lactis. Anaerobic fermentation was carried out in a shaker at 100 rpm, 37 °C for 24 hours, using processed cashew apple as the substrate, which was enriched with a nutrient solution containing mineral salts. The growth was estimated in colony-forming units (CFU/mL), during strategic intervals of fermentation times on selective bifidobacteria agar medium, and the medium's pH was monitored. The prebiotic fructooligosaccharide (FOS) was used as a control. The cashew apple showed bioactive properties, with ascorbic acid values of 4.58 ± 0.00 mg/100 g, total phenolic compounds of 366.85 ± 3.43 mg GAE/100 g, flavonoids of 85.03 ± 4.15 mg CE/100 g and antioxidant capacity of 17.78 ± 0.20 µM TEAC/g. Plate counts showed small white colonies and complete regular edges. The growth of bifidobacteria in FOS was 10 Log CFU/mL -1 after 24 hours of fermentation, while in the cashew apple the growth was 8.8 Log CFU mL -1 after 12 hours of fermentation, with a reduction in pH medium (pH 5.08) that left it slightly more acidic than the standard (pH 5.98). Thus, it can be inferred that the cashew apple presents important functional properties, with possible benefits to human health.

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