Utilização da cama de frango em meio de cultivo de Bacillus thuringiensis var. israelensis Berliner para o controle de Aedes aegypti Linnaeus

Bacillus thuringiensis var. israelensis (Bti) is one of the most important microrganisms used in bioinsecticide formulations. It has an application against insect vectors of several diseases. Despite his efficiency and environment safety, his use is limited by the production costs. All around the world, research have been performed to discovery materials that reduce the final costs of Bti insecticides. The present paper has tested the application of poultry litter as culture medium to Bacillus thuringiensis var. israelensis. The bioinsecticide was tested against thirty instar Aedes aegypti larvae and the performance has been compared with the waste cassava starch and citrus pulp media. The poultry litter has enabled the higher larvae mortality; it achieved 100% in 20 and 10mg.L-1 concentrations and exceeded 50% in 5mg.L-1. The others materials have got significant lower performances. The waste cassava starch was useful only in 20mg.L-1 concentration and falling in others values, and the citrus pulp medium has not reached 50% of larvae mortality even in the higher concentration (20mg.L-1). The chemical composition of poultry litter revealed the presence of 39% of nitrogen source and 4% of carbon source, beyond the higher concentrations of potassium and phosphorus.O Bacillus thuringiensis var. israelensis (Bti) é um dos principais microrganismos utilizados na formulação de bioinseticidas, possuindo grande aplicação no combate a insetos vetores de diversas doenças humanas. Apesar de eficiente e ambientalmente seguro, sua utilização ainda é limitada pelos custos de produção. Em todo mundo, pesquisas têm sido feitas em busca de matérias-primas que reduzam o custo final dos inseticidas de Bti. O presente trabalho testou a aplicação da cama de frango na composição do meio de cultivo para Bacillus thuringiensis var. israelensis. O bioinseticida resultante foi testado contra larvas L3 de Aedes aegypti e teve seu resultado comparado com os bioinseticidas produzidos com bagaço de mandioca e polpa cítrica. O meio com cama de frango possibilitou uma maior mortalidade de larvas, alcançando 100% nas diluições de 20 e 10mg.L-1 e ultrapassando 50% em 5mg.L-1. Os demais resíduos obtiveram resultados significativamente inferiores. O bagaço de mandioca foi efetivo apenas na diluição de 20mg.L-1, caindo nas demais concentrações, e a polpa cítrica sequer atingiu 50% de mortalidade na maior concentração do produto. A composição química da cama de frango revelou a presença de 39% de fonte de carbono e 4% de fonte de nitrogênio, além de elevadas concentrações de sais de potássio e fósforo. &nbsp

Proizvodnja fitaze fermentacijom pulpe citrusa i drugih ostataka agroindustrije s pomoću izolata gljiva

Phytases have important applications in human and animal nutrition because they hydrolyze the phytate present in legumes, cereal grains and oil seeds. This results in an increased availability of minerals, trace elements and amino acids as well as phosphate. Fifty potential phytase-producing fungal strains were isolated from a fertile soil obtained from the northern part of Paraná State in Brazil and other alternative sources using a selective media. Thereafter phytase production was evaluated in solid-state fermentation using different residues from the agroindustry supplemented with a nitrogen source at 60 % of moisture after 96 hours at 30 °C. The highest phytase activity (51.53 units per gram of dry substrate, U/g) was achieved with citric pulp and the soil isolate FS3 in solid-state fermentation. Furthermore, treatment of the substrates prior to fermentation in order to reduce microbial contamination was shown to affect phytase production during solid-state fermentation. Heat treatment resulted in an increase of the concentration of inorganic phosphate, a well known repressor of microbial phytase production, and therefore in a reduction of phytase production. UV exposure of the substrate was shown to reduce microbial contamination without affecting phytase production.Fitaze imaju važnu ulogu u prehrani ljudi i životinja jer hidroliziraju fitate leguminoza, zrnja žitarica i sjemenki uljarica, pa tako povećavaju pristupačnost minerala, elemenata u tragovima, aminokiselina i fosfata. Iz plodnog tla sjevernog dijela brazilske države Paraná, a i iz drugih izvora, na selektivnim podlogama izolirano je 50 sojeva gljiva koje mogu proizvesti fitaze. Nakon toga je proizvodnja fitaze ispitana uzgojem na čvrstoj podlozi od raznih ostataka agroindustrije, uz dodatak izvora dušika, pri 60 %-tnoj vlažnosti i 30 °C tijekom 96 sati. Najveća aktivnost fitaze (51,53 U/g suhe tvari) dobivena je uzgojem izolata FS3 iz tla na pulpi citrusa. Obrada supstrata prije procesa, radi smanjenja onečišćenja mikroorganizmima, utjecala je na proizvodnju fitaze. Toplinskom obradom povećala se koncentracija anorganskog fosfata, koji suzbija mikrobiološku proizvodnju fitaze. Izloženost supstrata UV-zrakama smanjuje onečišćenje mikroorganizmima, a pritom ne utječe na proizvodnju fitaze