Nitrification activity in the presence of 2-chlorophenol using whole nitrifying cells and cell-free extracts: batch and SBR assays.

Kinetic assays with a nitrifying consortium with whole nitrifying cells amended with 5 mg 2-CP-C/L and 100, 200, 300, or 500 mg NH4+-N/L were carried out in batch and nitrifying sequencing batch reactor (SBR) cultures. No nitrification activity was observed in batch assays with 100 mg NH4+-N/L and 5 mg 2-CP-C/L. Nevertheless, increasing the ammonium concentration from 200 to 500 mg NH4+-N/L allowed simultaneous ammonium and nitrite oxidation even in the presence of 5 mg 2-CP-C/L plus the halogenated compound consumption. Under these conditions, the ammonium monooxygenase enzyme participated in 2-CP consumption. Complete nitrification and simultaneous elimination of 5 mg 2-CP-C/L were achieved in the SBR amended with 200-500 mg NH4+-N/L. The inhibitory effect of 2-CP on the nitrite oxidation process completely disappeared under these conditions. Assays with nitrifying cell-free extracts, ammonium (100 mg NH4+-N/L), and 2-CP (5 mg 2-CP-C/L) were also conducted. In the absence of 2-CP, the nitrifying cell-free extracts maintained up to 60% of the nitrifying activity compared to whole-cells. Contrary to whole-cell assays, cell-free extracts were capable of simultaneously oxidizing ammonium and consuming 2-CP. However, the inhibitory effect of 2-CP on nitrification was still present as lower specific rates of ammonium consumption and nitrate production were obtained. Thus, these assays indicate that the presence of 2-CP affects both, the ammonium transport mechanism and the activity of nitrifying enzymes. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03764-z.

Experiencia micológica en la huasteca potosina / Micology experience in the Huasteca in San Luis Potosi state

Se realizó un estudio en una pequeña región de la zona Huasteca del Estado de San Luis Potosí, en donde los factores climatológicos y socioeconómicos favorecen el desarrollo de ciertas enfermedades de la piel. Se estudiaron un total de 62 pacientes con dermatosis, 19 (30.6 por ciento) tuvieron enfermedades micóticas de las cuales las dermatofitosis se presentaron con mayor frecuencia (75 por ciento), y en menor proporción cromomicosis, micetoma y pitiriasis versicolor