Molecular study of Pigeonpea

Table 3: Effect of nitrogen source on decolorization of Reactive Red M5B and ligninolytic enzymes production by fungal

isolate AGYP-1

Laccase activity

MnP activity

Nitrogen source

% Decolorization

(U ml -1 )

(U ml -1 )

Yeast extract

93.73±4.4

935.3±12.3

468.88±12.2

Peptone

87.34±3.7

837.8±23.7

377.93±8.9

Gelatine

96.74±1.7

1537.1±14.6

791.64±12.5

Urea

92.41±3.5

1170.4±12.8

518.47±11.2

Ammonium sulfate

74.33±4.1

143.46±10.9

45.40±7.7

Ammonium nitrate

60.34±2.7

111.52±6.3

54.37±6.3

3.4 Effect of Physico-chemical parameters on

3.4.2 Effect of pH

decolorization of Reactive Red M5B

The hydrogen ion concentration greatly affects various

3.4.1 Effect of static and shaking conditions

biological activities of organisms. The decolorization of

Reactive Red M5B was investigated in the range of pH

The isolate AGYP-1 exhibited maximum decolorization

3.0 to 8.0. As shown in figure 4, that the decolorization

of Reactive Red M5B (92.33±2.4%) under shaking

efficiency of the isolate AGYP-1 was found to be

condition, whereas, 65.34±4.2% color removal was

increase with an increase in pH, reaching maximum at

achieved in static condition on 12 th day incubation

pH 5.0 (91.17±3.2%). Further increase in pH resulted

(Fig. 3). Moreover, AGYP-1 displayed higher activities

into decrease in decolorization efficiency. However, at

of laccase (253.8±14.5 U ml -1 ) and MnP (70.36±8.6U

pH 4.0 and 6.0, the color removal was 74.18±4.4% and

ml -1 ) under shaking condition. The estimated biomass

85.86±3.8% respectively. Moreover, the maximum fungal

of the isolate was 0.257±0.04 and 0.164±0.03 g under

biomass (0.253±0.03 g) along with highest activities of

shaking and static conditions respectively. Conversely,

laccase (232.38±10.9 U ml -1 ) and MnP (69.27±3.6 U

the isolate showed very low level of laccase and MnP

ml -1 ) were obtained at pH 5.0, suggesting that acidic pH

activities (78.25±4.2 and 32.4±2.2 U ml -1 respectively)

favoured the decolorization of the dye. Vaithanomsat

in static condition. Moreover, it was found that laccase

et al . (2010) demonstrated maximum decolorization of

activity in all the experimental flasks was much higher

Reactive Black 5 along with highest laccase activity at

as compared to MnP activity, suggesting its possible role

pH 5.0 using white-rot fungus Dratronia sp. KAPI0039.

in decolorization process. Above results demonstrate that

Based on the study carried out by Young and Yu (1997),

shaking condition favored the growth of the isolate and

the azo-based dye was more effectively degraded by

resulted into 1.41 times higher decolorization of the dye.

white-rot fungi under an acidic condition. Many other

Thismaybeattributedtobetteroxygentransferandnutrient

reports suggest that the fungi can grow best at low pH

distribution as compared to static condition. Miranda et

normally ranging from 4.0 to 6.0. Furthermore, fungal

al . (2012) reported an effective decolorization of textile

ligninolytic enzymes show maximum activity at low pH;

dyes under shaking condition using Phanerochaete

hence, an efficient decolorization is observed at low pH

chrysosporum CCT1999, Lentinula edodes CCT4519

(Saranthima et al ., 2009; Patel and Gupte 2014).

and Curvularia lunata UFPEDA885. However, Kirby et

al . (2002) observed better dye decolorization by Phlebia

3.4.3 Effect of temperature

tremellosa under static condition. Many reports have

Temperature is an important environmental factor; change

described a relationship between ligninolytic enzyme

in temperature affects the biodegradation activities

activities and decolorization of different dyes by white

of microorganisms. The effect of temperature on

rot fungi (Erkurt et al . 2007; Moreira-Neto et al . 2013).

decolorization of Reactive Red M5B by isolate AGYP-1

505