Production of two novel laccase isoforms by a thermotolerant strain of Pycnoporus sanguineus isolated from an oil-polluted tropical habitat.
A thermotolerant and halotolerant strain of Pycnoporus sanguineus was isolated from an oil-polluted site in a tropical area located in Veracruz, Mexico. This strain was able to grow at 47 degrees C and in culture medium containing 500 mM NaCl. The strain was also tolerant to the presence of 30,000 ppm of crude Maya oil. A 68-kDa protein purified from submerged cultures exhibited laccase activity towards 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), guaiacol, syringaldazine, and o-dianisidine, for which it presented the highest affinity (Km = 43 microM). Two-dimensional gel electrophoresis analysis showed that, unusual for laccases, the enzyme has two active isoforms, with isoelectric points of 7.00 and 7.08. The purified enzyme showed high thermostability, retaining 40% of its original activity after 3 h at 60 degrees C. This property seems to correlate with a long "shelf-life," given that at 40 degrees C enzyme activity was only gradually lost over a 5-day period incubation. Both the fungus and its laccase are likely to have high potential for biotechnological applications.
Biotechnology Research Center, Autonomous University of the State of Morelos, Cuernavaca, Mexico.
Edgar
E
Dantán-González
Odón
O
Vite-Vallejo
Claudia
C
Martínez-Anaya
Mónica
M
Méndez-Sánchez
María C
MC
González
Laura A
LA
Palomares
Jorge
J
Folch-Mallol
D017753:Ecosystem; D004787:Environmental Pollution; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D007527:Isoenzymes / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D042845:Laccase / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D008800:Mexico; D010578:Petroleum; D024301:Plant Bark / Q000382:microbiology*; D011124:Polyporaceae / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D012965:Sodium Chloride / Q000494:pharmacology; D013379:Substrate Specificity; D014329:Tropical Climate
D005656:Fungal Proteins; D007527:Isoenzymes; D010578:Petroleum; D012965:Sodium Chloride; D042845:Laccase