The present study describes the immobilization of horseradish peroxidase (HRP) on magnetite-modified polyaniline (PANImG) activated with glutaraldehyde. After the optimization of the methodology, the immobilization of HRP on PANImG produced the same yield (25%) obtained for PANIG with an efficiency of 100% (active protein). The optimum pH for immobilization was displaced by the effect of the partition of protons produced in the microenvironment by the magnetite. The tests of repeated use have shown that PANImG-HRP can be used for 13 cycles with maintenance of 50% of the initial activity.

Discs of network polyvinyl alcohol-glutaraldehyde (PVAG) were synthesized and coated with polyaniline (PANI) using glutaraldehyde as a chemical arm (PVAG-PANIG-HRP disc). The best conditions for the immobilization were established as about 1.0 mg mL⁻¹of protein, for 60 min and pH 5.5. The soluble enzyme lost all of its activity after incubation at 70°C for 15 min, whereas the PVAG-PANIG-HRP disc retained about half of the initial activity for pyrogallol. The same PVAG-PANIG-HRP disc was used consecutively three times without any activity lossbut presented 25% of the initial activity after the 7th use. PVAG-PANIG-HRP disc retained approximately 80% and 60% of its initial activity after 60 and 80 days of storage, respectively. Resorcinol, m-cresol, catechol, pyrogallol,α-naphthol,βnaphthol, and 4, 4′-diaminodiphenyl benzidine were efficiently oxidized by the PVAG-PANIG-HRP disc (from about 70% to 90%), and it was less efficient towards aniline, phenol, and 2-nitrosonaphthol.

Cicadas are usually studied regarding their importance in agriculture. However, the possibility of this group to represent a pulse of nutrients can also imply on the success of a given species in the biome. The aim of this study was to assess the level of total soluble proteins and lipids of Fidicina mannifera (Fabricius, 1803), and to determine whether the species can promote a pulse of nutrients in two vegetation classes of the Brazilian Cerrado. To assess the pulse of nutrients, it was concluded the determination of total soluble proteins and lipids from samples of males and adult females of F. mannifera, and the spatial distribution of exuviae of this species was also calculated in two vegetation classes of the Brazilian Cerrado. The amount of protein provided by each individual did not differ between males and females (p = 0.66) but females had 40% more lipids than males (p = 0.05). Regarding F. mannifera the gallery forest offered 11.75 g/ha of protein, 3.91 g/ha of lipids, and the Cerrado stricto sensu offered 4.25 g/ha of protein, and 1.41 g/ha of lipid. The male cicadas have a hollow abdomen, which houses a resonance chamber for sound production in order to attract females to mate, and females store larger amounts of lipids, mainly located in the abdominal cavity, where the body fat is directly linked to the reproductive system for the development of the ovaries and egg production after emergence. The mass occurrence of F. mannifera in the Brazilian Cerrado and the fast availability of proteins and lipids make this species a food resource that can directly impact the diet of secondary consumers and scavengers, although the amount of nutrients available by F. mannifera does not promote a pulse of nutrients in the study site.

Dentre as diversas agriculturas ecológicas, os sistemas agroflorestais (SAF´s) se apresentam como promissores enquanto alternativa para a produção de alimentos através de práticas que participam dos processos naturais, conservando os solos e recuperando sua fertilidade. Foram utilizados dados de análise química e de textura de solos (0 a 20cm de profundidade) dos 20 SAF´s e das áreas externas classificadas quanto ao uso do solo (pastagem ou ecossistemas naturais) em diversos municípios do estado de Goiás e no Distrito Federal. Para testar as diferenças dos solos utilizamos teste não-paramétrico de Kruskall-Wallis para cada parâmetro de solo entre os diferentes agroecossistemas. Também foi realizado análises dos componentes principais para verificar quais as variáveis apresentaram maior efeito e relação entre os parâmetros de solo e os diferentes agroecossistemas. Dentre os atributos de solos em sistemas agroflorestais no Cerrado, os atributos de pH, cálcio (Ca2+), H+Al, fósforo (P-), matéria orgânica (MO), soma de bases (SB) e saturação de bases (V%) apresentaram diferenças entre os usos do solo (SAFs, pastagem ou ecossistemas naturais). As agroflorestas mais antigas, que já apresentam estruturas florestais, com sombreamento da área, e aporte de serrapilheira constante no solo, apresentaram maior qualidade do solo, correlacionando-se com maiores teores de P-, magnésio (Mg2+), (Ca2+), potássio (K+), pH e MO. Os atributos que apresentaram maior influência na análise multivariada foram Ca2+, Mg2+, SB, CTC, Areia, Silte, Argila, H+Al, Al3+ e MO, podendo ser variáveis importantes para entender a variação desses elementos no solo em sistemas agroflorestais e diferentes usos do solo no Cerrado. Assim, concluímos que a deposição de matéria orgânica no SAF é capaz de alterar os atributos de fertilidade do solo ao longo do seu desenvolvimento. Palavras-chave: savana brasileira; agroecossistemas; qualidade do solo; matéria orgânica. Soil fertility attributes in different agroforestry systems in the Cerrado Among the various ecological agricultures, agroforestry systems (SAFs) appear promising as an alternative for food production through practices that participate in natural processes, conserving soils and recovering their fertility. Data from chemical and texture analyses of soils (0 to 20 cm deep) of the 20 AFSs and external areas classified according to land use (pasture or natural ecosystems) in several Goiás municipalities and the Federal District were used. To test the soil differences, we used the non-parametric Kruskall-Wallis test for each soil parameter among the agroecosystems. Principal component analyses were also performed to verify which variables had the greatest effect and relationship between the soil parameters and agroecosystems. Among the soil attributes in agroforestry systems in the Cerrado, the attributes of pH, calcium (Ca2+), H+Al, phosphorus (P-), organic matter (MO), the sum of bases (SB) and base saturation (V%) showed differences between land uses (SAFs, pasture or natural ecosystems). Older agroforests, which already have forest structures, with the shading of the area and constant contribution of litter in the soil, presented higher soil quality, correlating with higher contents of P-, magnesium (Mg2+), (Ca2+), potassium (K+), pH and MO. The attributes that showed the greatest influence in the multivariate analysis were Ca2+, Mg2+, SB, CEC, Sand, Silt, Clay, H+Al, Al3+ and OM, and may be important variables to understand the variation of these elements in the soil in agroforestry systems and different land uses in the Cerrado. Thus, we conclude that the deposition of organic matter in the SAF can alter soil fertility attributes throughout its development. Keywords: Brazilian savanna; agroecosystems; soil quality; organic matter.