Electrochemical Sensor And Its Application In The Production Of The Laccase From Penicillium Simplicissimum Isolated From Composting

Composting is considered as a useful process for the disposal of municipal and agricultural solid waste, in which enzymes play an important role. Electrochemical sensors are electrochemical devices that are based on the signal transmission of biochemical reactions. In comparison with the conventional chemical and biochemical analytical methods, the electrochemical sensors have the advantages of convenience, time-saving as well as high precision. Moreover, they are convenient for computers to collect and process data, and the sample won't be damaged or polluted. Electrochemical sensor as a new kind of analytical tool is widely applicable in monitoring and controlling of composting.The sensors have been one of most concerned areas because of their specificity and high-efficiency. In the design and fabrication of electrochemical sensors, the key technology is to modify the working electrode with the multi-wall carbon nanotubes (CNTs) which can enhance the electrochemical signal of the laccase in the microenvironment. In this paper, the research was aimed to develop the production of the laccase from Penicillium simplicissimum isolated from the composting, and characterize the electrochemical activity of the laccase as well as the enhanced signal from the introduction of the CNTs. The detailed research contents are summarized as follows:The optimal fermentation conditions for laccase production by Penicillium simplicissimum in shake- flask cultivation were studied. The composition of fermentation medium was maltose 2g/L, peptone 1.2 g/L,100 mL/L Massive elements solution,25 mL/L Trace elements solution,100μg/L VB1,0.05% Tween 80. Shaking culture of the liquid containing 107conidia/mL for 8 day at the regime of 30℃and 150 r/min resulted in the enzyme activity of 12.44 U/L. The optimum pH of production Laccase was 4.0, the optimal concentration of Cu2+ was 60 u mol/L. An electrochemical sensor for detection of the activity of laccase from Penicillium simplicissimum isolated from the composting has been developed. The sensor is based on glassy carbon electrode modified with multi-wall carbon nanotubes (CNTs). The introduction of CNTs into this system can greatly enhance the electrochemical signal in this assay more sensitively, selectively and rapidly than that in conventional spectrophotometric assays. It was found that the optimal pH value of the electrolyte was 5.6. The results showed a good linear correlation between the current and the concentration of laccase activities measured by spectrophotometry, where the current slope was measured by chronoamperometry with a coefficient of 0.9835. Therefore, this electrochemical sensor can be used for rapid detection of laccase activity from Penicillium simplicissimum. Furthermore, it may be potentially used for rapid quantification of Penicillium simplicissimum according to the relationship between the laccase activities and the biomass.