Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Screening, Purification, and Characterization of an Extracellular Prolyl Oligopeptidase from Coprinopsis clastophylla: Jen-Tao Chen , Mei-Li Chao , Chiou-Yen Wen , Wen-Shen Chu; J. Microbiol. 2012;50(4):652-659. Published online August 25, 2012; DOI: https://doi.org/10.1007/s12275-012-2099-0

Abstract: Culture filtrates of 22 mushrooms were screened for extracellular prolyl oligopeptidase activity. Four strains with relatively high enzyme activity were all from inky cap mushrooms. The production of Coprinopsis clastophylla prolyl oligopeptidase was associated with the growth of the fungus and the enzyme was not released by cell lysis. The enzyme was purified 285-fold to a specific activity of 52.05 U/mg. It was purified to a single band on a native polyacrylamide gel. However, the enzyme separated into three bands on a sodium dodecyl sulfate-polyacrylamide gel with mobility corresponding to molecular weights of approximately 84, 60, and 26 kDa. The results of tandem mass spectrometric analysis revealed that the 60 kDa protein was likely a degradation product of the 84 kDa protein. The isoelectric point of the purified enzyme was 5.2. The purified enzyme had an optimal pH and temperature of 8.0 and 37°C, respectively. Diisopropyl fluorophosphate (DFP), p-chloromercuribenzoaic acid (PCMB), Hg2+, and Cu2+ strongly inhibited C. clastophylla prolyl oligopeptidase. This enzyme is a serine peptidase and one or more cysteine residues of the enzyme are close to the active site.

A Bacterium Belonging to the Burkholderia cepacia Complex Associated with Pleurotus ostreatus: Ricardo Yara , Walter Maccheroni Junior , Jorge Horii , Joao Lucio Azevedo; J. Microbiol. 2006;44(3):263-268.; DOI: https://doi.org/2387 [pii]

Abstract: Pleurotus ostreatus is a widely cultivated white-rot fungus. Owing to its considerable enzymatic versatility P. ostreatus has become the focus of increasing attention for its possible utility in biobleaching and bioremediation applications. Interactions between microorganisms can be an important factor in those processes. In this study, we describe the presence of a bacterial species associated with P. ostreatus strain G2. This bacterial species grew slowly (approximately 30 days) in theliquid and semi-solid media tested. When P. ostreatus was inoculated in solid media containing Tween 80 or Tween 20, bacterial microcolonies were detected proximal to the fungal colonies, and the relevant bacterium was identified via the analysis of a partial 16S rDNA sequence; it was determined to belong to the Burkholderia cepacia complex, but was not closely related to other fungus-isolated Burkholderiaceae. New specific primers were designed, and confirmed the presence of in vitro P. ostreatus cultures. This is the first time that a bacterial species belonging to the B. cepacia complex has been found associated with P. ostreatus.

Enhanced Production of Exopolysaccharides by Fed-batch Culture of Ganoderma resinaceum DG-6556: Hyun Mi Kim , Soon-Young Paik , Kyung Soo Ra , Kwang Bon Koo , Jong Won Yun , Jang Won Choi; J. Microbiol. 2006;44(2):233-242.; DOI: https://doi.org/2360 [pii]

Abstract: The objectives of this study were to optimize submerged culture conditions of a new fungal isolate, Ganorderma resinaceum, and to enhance the production of bioactive mycelial biomass and exopolysaccharides (EPS) by fed-batch culture. The maximum mycelial growth and EPS production in batch culture were achieved in a medium containing 10 g/l glucose, 8 g/l soy peptone, and 5 mM MnCl2 at an initial pH 6.0 and temperature 31°C. After optimization of culture medium and environmental conditions in batch cultures, a fed-batch culture strategy was employed to enhance production of mycelial biomass and EPS. Five different EPS with molecular weights ranging from 53,000 to 5,257,000 g/mole were obtained from either top or bottom fractions of ethanol precipitate of culture filtrate. A fed-batch culture of G. resinaceum led to enhanced production of both mycelial biomass and EPS. The maximum concentrations of mycelial biomass (42.2 g/l) and EPS (4.6 g/l) were obtained when 50 g/l of glucose was fed at day 6 into an initial 10 g/l of glucose medium. It may be worth attempting with other mushroom fermentation processes for enhanced production of mushroom polysaccharides, particularly those with industrial potential.

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