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In this study, two laccase isoenzymes (Lac1 and Lac2) from the culture supernatant of Trametes hirsuta MX2 were purified, and the genes (Lac1 and Lac2) coding the isoenzymes were cloned. Both Lac1 and Lac2 contained an open reading frame of 1563 bp with an identity of 79%. The two isoenzymes showed significant biochemical differences. The maximal activities of Lac1 and Lac2 were at pH 2.5 with 2-2′-azino-di-(3-ethylbenzthiazoline sulfonic acid) (ABTS), and the optimal temperatures for the activities of Lac1 and Lac2 were 60 and 50 °C, respectively. Lac1 exhibited excellent resistance to acidic conditions and retained 62.17% of its initial activity at pH 2.5 after a 72-h incubation. Lac2 was more thermostable than Lac1 with half-lives (t1/2) of 9.58 and 3.12 h at 50 and 60 °C, respectively; the t1/2 of Lac1 were only 4.19 and 0.88 h, respectively. Both Lac1 and Lac2 isoenzymes have a strong tolerance to Mg2+, Mn2+, Cu2+, and EDTA (50 mM). At a low concentration of 0.05 U mL−1, the enzymes could decolorize towards Remazol Brilliant Blue R, Acid Red 1, Crystal Violet, and Neutral Red in the presence of ABTS. These unusual properties demonstrated that the two laccases have strong potential for specific industrial applications. [ABSTRACT FROM AUTHOR]

Wood preservation is one of the most effective methods to prevent damage caused by termites. Sodium fluoride (NaF) is a well-known fungicide for preventing decay in timber due to its excellent diffusion in wood. In this study, the toxicity of NaF to the termites Reticulitermes flaviceps and its potential leachability as wood preservative were assessed. While termites were in contact with NaF-treated filter paper in a Petri dish for nine days, termites were found completely dead while the papers were treated by NaF at concentration of 0.5 % (wt/wt) or above. Wood blocks of Pinus massoniana were treated with five different concentrations of NaF (0.1, 0.25, 0.5, 1 and 2 %) respectively, and then exposed to a non-soil-contact field leaching experiment. After 4 weeks, retention levels of NaF in the wood blocks dropped from 0.075-0.834 % to 0.057-0.284 %. A choice test, in which NaF-treated and untreated wood blocks were exposed to the termites R. flaviceps was conducted. The results showed NaF, even at retention of 0.057 % (wt/wt), could significantly inhibit termite feeding in the treated blocks. The results suggest that NaF is a suitable wood preservative with anti-feedant activity against termites. [ABSTRACT FROM AUTHOR]