Production parameter optimization for laccases by Aspergillus niger

observed on 6th day of incubation. The incubation time plays an important role in

the growth of microorganisms and enzyme secretion. Enzyme production increases

with time till 72 h after that enzyme production decreased due to depletion of

macro and micronutrients in the production medium.

Effect of carbon source (2%) on laccase activity

Laccase activity was observed maximum with 2% glucose as carbon source

(0.0418 U/ml).The present study is in agreement with study conducted by Ding

et al. (2012) in which 20 g/l glucose was most as effective sole carbon source,

resulting in the highest laccase production(Fig: 4). In a similar kind of study

conducted by Sivakumar et al., (2010)reported that starch supported for the high

laccase production. Study conducted by Adejoye and Fasidi, (2009) in which the

best laccase activity of (47.5 ± 1.85 U/ml) was induced by mannose. It has been

reported that the carbon source is the most important factor in laccase production,

and that the addition of suitable amount of other sugar to the culture media has

a benign influence on laccase synthesis. Among the carbon source, glucose is

readily utilizable substrate which would promote laccase production. Medium

containing glucose showed the highest laccase activity as enzymes are substrate

specific. Since, glucose is a monosaccharide which is easily broken down, quickly

utilized by the microorganisms. It has already been demonstrated that substrates

that are efficiently and rapidly utilized by the organism results in high levels of

laccase activity.

Fig: 4 Effect of carbon source (2%) on laccase activity

Effect of nitrogen source (2%) on laccase activity

Laccase activity was observed maximum with 2% peptone as nitrogen source

(0.0418 U/ml) (Fig: 5).The present study is in contrast with Ding et al. (2012),

Sivakumar et al. (2010) and Adejoye and Fasidi (2009). Ding et al. (2012)

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