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A comparative rapid and sensitive method to screen l-asparaginase producing fungi
Mohan A Dhale1, H Puttananjaiah Mohan-Kumari2
1Department of Food Microbiology, Central Food Technological Research Institute, Council of Scientific and Industrial Research, Mysore, 570 020, India.
Abstract:
Fungi are well known to produce various industrial enzymes and secondary metabolites with different colours. Fungi producing l-asparaginase enzyme are conventionally screened on medium containing phenol red (PR). The contrast between enzyme-hydrolysed zone and unhydrolysed l-asparagine is not very evident and distinct in medium containing PR and bromothymol blue (BB) due to coloured secondary metabolite production. Thus, PR and BB limit and affect the detection and screening method. In the present investigation, an improved method for screening is reported by comparing with PR and BB, wherein methyl red (MR) is incorporated as pH indicator. The enzyme activity was distinctly observed (red and light-yellow) in MR incorporated medium compared to PR and BB.
Insights
This study introduces methyl red (MR) as a superior pH indicator for screening fungi that produce l-asparaginase. The improved method offers clearer visual detection of enzyme activity compared to conventional phenol red (PR) and bromothymol blue (BB) indicators.
Area of Science:
- Microbiology
- Biotechnology
- Enzyme Technology
Background:
- Fungi are prolific producers of industrial enzymes and colored secondary metabolites.
- Conventional screening for l-asparaginase uses phenol red (PR) or bromothymol blue (BB) pH indicators.
- Colored fungal metabolites interfere with PR and BB, obscuring clear detection of l-asparaginase activity.
Purpose of the Study:
- To develop an improved and more distinct method for screening fungal l-asparaginase production.
- To compare the efficacy of methyl red (MR) with PR and BB indicators for l-asparaginase screening.
Main Methods:
- Fungal cultures were screened for l-asparaginase production on media incorporating different pH indicators: PR, BB, and MR.
- Visual assessment of enzyme activity was performed by observing color changes in the indicator zones.
- Comparison of detection clarity and distinctness between the indicators was conducted.
Main Results:
- Methyl red (MR) incorporated medium provided a distinctly observable color change (red to light-yellow) indicating l-asparaginase activity.
- PR and BB media showed less evident contrast due to interference from fungal secondary metabolites.
- The improved MR method enhances the detection and screening of l-asparaginase-producing fungi.
Conclusions:
- Methyl red (MR) is a more effective pH indicator than PR and BB for screening fungal l-asparaginase production.
- The enhanced visual contrast in MR medium facilitates accurate and efficient detection of enzyme activity.
- This improved screening method aids in the identification of fungi relevant for industrial enzyme production.
