Screening of polar streptomycetes able to produce cold-active hydrolytic enzymes using common and chromogenic substrates

Abstract

A semi-qualitative screening based by proteases and amylases production on Gauze agar media with 1% starch or 1% casein, as single carbon or nitrogen sources was made first time by using radial diffusion in gel method for active cold adapted strains selection by cultivation from 5ºC to 20ºC. Another step of screening was made on starch or casein medium adjusted with insoluble chromogenic functionalized substrates based on AZCL (azurine-crosslinked amylose or casein) using a plate assay based on the visible solubilization of small particles of AZCL and the formation of blue haloes around the active colonies growth on agar media on Petri dishes. These substrates are insoluble in buffered solutions, but rapidly hydrate to form gel particles which are readily and rapidly hydrolysed by specific hydrolaseís releasing soluble dye-labelled fragments by develop a blue specific zone around the colony during cultivation. This technique provides a specific, reliable and rapid simultaneous detection of high active hydrolaseís producing strains. It has a great potential for increasing the efficacy of screening streptomycetes able to produce hydrolytic enzymes as amylases and proteases. The selected streptomycetes strains isolated from polar soils are able to biosynthesis amylases and proteases cold-adapted at low temperatures (from 5 to 20ºC) and alkaline pH.