Acetaldehyde production byRothia mucilaginosaisolates from patients with oral leukoplakia

Rothia mucilaginosahas been found at high abundance on oral leukoplakia (OLK). The ability of clinical isolates to produce acetaldehyde (ACH) from ethanol has not been investigated. The objective of the current study was to determine the capacity ofR. mucilaginosaisolates recovered from OLK to generate ACH. Analysis ofR. mucilaginosagenomes (n = 70) shows that this species does not normally encode acetaldehyde dehydrogenase (ALDH) required for detoxification of ACH. The predicted OLK metagenome also exhibited reduced ALDH coding capacity. We analysed ACH production in 8 isolates ofR. mucilaginosaand showed that this species is capable of generating ACH in the presence of ethanol. The levels of ACH produced (mean = 53 mu M) were comparable to those produced byNeisseria mucosaandCandida albicansin parallel assays. These levels were demonstrated to induce oxidative stress in cultured oral keratinocytes. This study shows thatR. mucilaginosacan generate ACH from ethanolin vitroat levels which can induce oxidative stress. This organism likely contributes to oral ACH levels following alcohol consumption and the significance of the increased abundance ofR. mucilaginosain patients with potentially malignant disorders requires further investigation.