A Study on the Growth of Lichthemia corymbifera on Different Cultural Media which Demonstrate the Needs of Strong Antifungal Agent in Baird Parker Medium for the Isolation of Staphylococcus aureus from Spice Samples

Abstract

A heavy fungal growth was observed on Baird Parker agar (BPA) plates while testing a chili ground sample for Staphylococus aureus as per USFDA BAM method and the fungus was identified as Lichtheimia corymbifera. The ability of L. corymbifera to grow in different bacterial media being used for spice sample analysis was assessed with two general and five selective bacterial media and compared with two fungal media. Upon 48 hours of incubation at 35± 1 ºC, the growth was calculated by measuring the diameter of fungal colony. BPA plates showed highest growth of 82±1mm in diameter followed by Nutrient Agar (NA) (65±1mm), Bismuth Sulfite Agar (BSA) (56±1mm), Potato Dextrose Agar (PDA) (52±1mm), Plate Count Agar (PCA) (50±1mm), Dichloran Glycerol Agar (DGA) (41±2mm) and Violet Red Bile Glucose Agar plates (VRBGA) (30±1mm). Measurable growth of L. corymbifera was not observed in Xylose Lysine deoxy-cholate Agar (XLDA) and Hecktoen Enteric Agar (HEA) plates for 48 hours of incubation at 35 ºC. The results indicated that the bacterial media such as BPA, NA, BSA, PCA and VRBGA were not able to inhibit the growth of L. corymbifera to a desirable level. The present study emphasizes the need to incorporate extra antifungal agents in BPA medium whenever used for spice sample analysis.