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Physiological and biochemical specific ways to cultivate some strains of micromycetes that produce lipolytic enzymes


Author: Sîrbu Tamara
Degree:doctor of biology
Speciality: 03.00.07 - Microbiology
Year:2005
Scientific adviser: Alexandra Deseatnic-Ciloci
doctor, associate professor (docent), Institute of Microbiology and Biotechnology of the ASM
Scientific consultant: Valeriu Rudic
doctor habilitat, professor, Institute of Microbiology and Biotechnology of the ASM
Institution: Institute of Microbiology and Biotechnology of the ASM
Scientific council:

Status

The thesis was presented on the 7 December, 2004
Approved by NCAA on the 27 January, 2005

Abstract

Adobe PDF document – 0.45 Mb / in romanian

Keywords

Aspergillus niger, Rhizopus arrhizus, lipolytic enzymes, nutritive media, lipolytic activity, inductors, coordination compounds, strain

Summary

The work deals with the isolation of new perspective strains of microscopic fungi producing hydrolytic enzymes, as well as with studying their physiological, biochemical properties and their enzyme forming character.

A comparatively cheap nutritive medium containing two salts and soybean flower was suggested as a result of studying the morphological - cultural and physiological - biochemical properties of the selected producers.

Mutagenesis and coordinative compounds were found to be able to considerably increase the productivity of the cultures.

Variants with increased (by many times) lipase synthesis were obtained from the strain Rhizopus arrhizus F 67 through γ-irradiation. The strains Rhizopus arrhizus F 67 and Aspergillus niger 412 reacted differently to coordinative compounds. This made possible to suggest that their lipolytic enzyme complexes are different and have different mechanisms of action. Complex compounds increasing lipase activity by 25-47% were individually selected for each strain.

Camphor, fir tree and soybean oils were shown to be potential inductors of lipolytic activity.

Enzyme complexes with lipolytic action were isolated from the cultural liquid of the selected producers. Their specificity was determined and a quality characterization was given, it was found to be able to synthesize the enzyme complex in practically purified condition. The strain Aspergillus niger 412 synthesizes an enzyme complex that contains, besides the lipases, other enzymes of amylolytic and cellulolytic activity.

The obtained results show that the selected strains can be numbered among the perspective lipase producers and can be used in various practical ways.