A newly isolated Paecilomyces sp. WSH-L07 for laccase production: isolation, identification, and production enhancement by complex inducement

Abstract

Laccase can catalyze the oxidation of a wide range of organic and inorganic substrates. In this study, an easily detectable method was employed for screening laccase-producing microorganisms by using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) as laccase-secretion indicator. A novel laccase-producing strain was isolated and identified as Paecilomyces sp. WSH-L07 according to the morphological characteristics and the comparison of internal transcribed spacer (ITS) ribosomal DNA (rDNA) gene sequences. In further investigation, the production of laccase by Paecilomyces sp. WSH-L07 was greatly enhanced by the nontoxic inducers of copper sulphate and methylene blue. Under the induction of 50 microM copper sulphate and 20 microM methylene blue, the maximum laccase production was obtained. When these inducers were added into cultivation medium at 24 h and 12 h, respectively, an increment of about 100 times of laccase activity compared with that of in inducer-free medium and about two times of that of in single copper-supplemented medium was observed. Compared with other Paecilomyces species, Paecilomyces sp. WSH-L07 exhibit the better laccase-producing characteristics with an activity of 1,650 U/l on the eighth day, suggesting its potential ability for industrial application.

Improvement of laccase production and its properties by low-energy ion implantation

“…WSH-L07 was isolated from crop soil and deposited in Lab of Biosystem and Bioprocess Engineering, School of Biotechnology, Jiangnan University, China [17]. Both the wild strain and laccase active mutants were grown at 30°C on potato dextrose agar (PDA) slants for preservation, or cultivated for 7 days in 250 mL flasks containing 100 mL modified yeast extract peptone dextrose (YPD-Cu) medium at 30°C and 150 r/min.…”

“…The selective plates (PDA-ABTS) used for preliminary screening were supplemented with 0.5 g/L 2,2 0 -azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) (Sigma Chemical Co., USA) in PDA medium before autoclaving [17]. The YPDCu medium containing glucose 20 g/L, peptone 5 g/L, yeast extract 2 g/L, and CuSO 4 100 lM (initial pH 6.5) was used for laccase production [17].…”

“…Primary screening of laccase active mutants was visually carried out based on the intensity of the dark-green dye [17]. The mutants with obvious dark-green dye were inoculated on PDA slants and incubated at 30°C until sporulation.…”

“…The microorganism used in this work was isolated from soil and identified as Paecilomyces sp., which exhibited a much higher level of laccase synthesis with an average activity of 820 U/L on the eighth day, compared with other strains of Paecilomyces species [15][16][17]. As a thermophilic microorganism [15,18], Paecilomyces sp.…”

Alachlor oxidation by the filamentous fungus Paecilomyces marquandii

“…The genus of Paecilomyces represents ubiquitous soil fungi, often isolated from heavy metal polluted areas [21][22][23]. Its remarkable enzyme activity and degradative abilities were also documented [24][25][26] Literature data concerning alachlor degradation by soil microbial communities or pure microorganism cultures and their metabolic pathways are limited and usually reveal only a few byproducts [27][28]. Only Tiedje and Hagedorn, [29] and Sette et al [30] documented the degradation of alachlor by pure cultures of soil fungus Chaetomium globosum and soil streptomycetes and proposed a microbial pathway of herbicide transformation.…”