Molecular study of Pigeonpea

able to grow and decolorize dyes in MM agar medium.

The isolate grew well on malt extract agar plate covering

However, the isolate AGYP-1 showed rapid and effective

the entire petri plate within 10 days of incubation. The

decolorization of Reactive Red M5B, Acid Green GLW,

aerial mycelia were found to be dense and white in

Reactive Violet 5R and Reactive Red HE8B on solid

color (Fig. 1B). Based on above observations, the isolate

medium. The decolorization of Reactive Red M5B

AGYP-1 was identified as white rot fungus belonging to

(100 mg l -1 ) started on 3 rd day (Fig. 1A) and progressed

class basidiomycete.

rapidly along with the radial growth of AGYP-1 resulting

The use of chromogenic substrates like ortho-dianisidine,

into complete removal within 10 days. Furthermore, an

ABTS, guaiacol etc. is considered as important aspect for

adsorption of dye was not evident on fungal mycelia

the detection of ligninolytic enzymes. In the present study,

indicating decolorization of the dye was truly a microbial

all isolates were screened on the SDA plates amended

process. Other fungal isolates showed lesser degree of

with 0.01% ortho-dianisidine. The oxidation of substrate

decolorization on the solid media. The initial identification

was observed as brown colored zone surrounding the

by microscopy demonstrated that the mycelia of AGYP-1

mycelia of the culture indicating Bevandamm’s reaction.

were white and septate with abundant clamp connection.

Out of four isolates, AGYP-1 and AGYP-4 showed

Table 1: Decolorization of different textile dyes by fungal isolate AGYP-1. Concentration of each dye was 100 mg l -1

Dye

λ max

Molecular weight

CAS No.

% Decolorization

Acid Maroon V

523

628.27

12220-20-1

51.22±3.6

Reactive Red BS

517

NA

88232-20-6

45.97±3.5

Acid Red F2R

510

454.43

6406-56-0

25.28±1.8

Reactive red M5B

538

615.34

12226-03-8

91.36±4.8

Acid Red 3BN

551

NA

12234-99-0

10.69±2.2

Reactive Blue 3R

577

NA

12225-45-5

88.58±5.9

Reactive Violet 5R

560

735.59

12226-38-9

86.54±4.8

Acid Red BB

532

862.28

6548-30-7

50.78±4.1

Acid Green GLW

617

706.73

6408-57-7

65.0±5.3

Reactive Red HE8B

548

1752.11

71870-80-5

85.49±6.1

NA-Not available

Table 2: Effect of co-substrate on decolorization of Reactive Red M5B

and ligninolytic enzymes production by fungal isolate AGYP-1

Laccase activity

MnP activity

Carbon source

% Decolorization

(U ml -1 )

(U ml -1 )

Glucose

91.35±3.5

235.8±9.5

88.4±5.5

Sucrose

74.32±5.4

156.9±13.3

34.36±2.6

Xylose

89.55±2.8

219.4±6.9

62.85±4.5

Maltose

96.11±2.7

572.34±24.6

171±7.2

Lactose

78.88±3.4

145.26±12.9

36.25±8.5

Fructose

87.44±1.9

89.4±7.6

38.07±2.5

Starch

81.07±6.2

179.4±9.8

70.01±5.3

Sodium acetate

64.32±3.3

21.01±3.3

10.16±4.8

503