Atividade enzimática de lysobacter sp. isolada de penas de pinguins da Ilha de Rei George, Antártica

Abstract

Keratinolitic micro-organisms are found in diverse environments, having already been described between fungi and bacteria. Among the microbial enzymes that have been gaining prominence are the keratinases, responsible for the keratin degradation. The aim of this study is to isolate and to identify micro-organisms producing keratinases from decomposing feathers of penguins (Pygoscelis antarctica and Pygoscelis papua) from King George Island, Antarctica. The cultivation of micro-organisms was performed on Ágar feather meal plates at room temperature (± 25 °C and 8 ºC) and, afterwards, they were stored in the refrigerator (8 °C). The selected micro-organisms were identified through molecular analysis, by obtaining the sequence of the gene 16S from rDNA. For an initial assessment of the proteolytic potential, the isolates were inoculated on milk-agar (MA) and incubated for 7days at 8 °C for one week, at 25 °C and 37 °C for up to 48 hours, on pHs 5,0,7,0, 9,0 and 11,0. Those able to form halos on MA were selected for enzyme tests on feather meal broth substrate. For keratinolitic determination azokeratin substrate was used. The isolate identified through gene 16S as Lysobacter sp. was capable of growing on agar feather meal as the sole carbon and nitrogen source, and it showed the formation of halos on MA, and produced keratinase when inoculated on feather meal broth substrate and incubated at 8 °C and 20 °C, pH 7.0. This is one of the first studies to confirm the existence of keratinolitic protease producing bacteria in the Antarctic environment, which are active in temperatures below 25 °C.