Improved naringinase double screen plate assay: progress towards the perfect screening

Naringinase is an important enzyme for commercial purposes due to its dual activity as both α-l-rhamnosidase and β-d-glucosidase. The traditional method for screening microbes that produce naringinase involves growing them on naringin agar, but this method has limitations and result in false positive results. This is because the growth on the naringin agar plate could be due to the presence of other organisms that produce rhamnosidase or other glucosidases, or those that use agar as a carbon source, rather than actual naringinase producers. To address these limitations, a double screen plate assay was developed using synthetic substrates, to separately test for β-d-glucosidase and α-l-rhamnosidase activity. The presence of a yellow zone of p-nitrophenol indicates the action of these enzymes, and the intensity of the yellow colour zone indicates the potential for naringinase production. This new screening method is a significant improvement in identifying real naringinase producers and represents progress towards a more reliable screening assay.