Ligninolytic fungus Polyporus sp. S133 mediated metabolic degradation of fluorene

ABSTRACT This study aimed to investigate the impact of nonionic surfactants on the efficacy of fluorine degradation by Polyporus sp. S133 in a liquid culture. Fluorene was observed to be degraded in its entirety by Polyporus sp. S133 subsequent to a 23-day incubation period. The fastest cell growth rate was observed in the initial 7 days in the culture that was supplemented with Tween 80. The degradation process was primarily modulated by the activity of two ligninolytic enzymes, laccase and MnP. The highest laccase activity was stimulated by the addition of Tween 80 (2443 U/L) followed by mixed surfactant (1766 U/L) and Brij 35 (1655 U/L). UV-vis spectroscopy, TLC analysis and mass spectrum analysis of samples subsequent to the degradation process in the culture medium confirmed the biotransformation of fluorene. Two metabolites, 9-fluorenol (λmax 270, tR 8.0 min and m/z 254) and protocatechuic acid (λmax 260, tR 11.3 min and m/z 370), were identified in the treated medium.

A new fragmentation rearrangement of the N-terminal protected amino acids using ESI-MS/MS.

A novel fragmentation rearrangement reaction with a carboxyl oxygen negative charge migration was observed in the N-terminal protected amino acids including Fmoc-protected phosphoserine. phosphothroenine, and phosphotyrosine and their analogues using the electrospray ionization tandem mass spectrometry (ESI-MS/MS). The possible mechanism of a five-membered ring transition state was proposed and supported by the further experiments. It was found that the tendency of the rearrangement was determined by the blocking status of its C-terminal and the reaction was proved to be independent of the N-terminal and side-chain protecting groups of the amino acids.