Pentachlorophenol removal from slightly acidic mineral salts, commercial sand, and clay soil by recovered Arthrobacter strain ATCC 33790

Arthrobacter strain ATCC 33790, a pentachlorophenol (PCP)-metabolizer isolated by the author, has been recovered after 10 years of storage. The freeze-dried preparation grown on half-strength Trypticase Soy Broth adapted to utilize PCP within 1 week. Cultures grown on PCP-nutrient agar were found to utilize PCP in mineral salts medium within 2-3 days. The culture was prepared for continuous growth at pH 6.5 by successive feeding of 100-110 mg solid aliquots of PCP to a 1-l culture initially grown at pH 7.4. Continuous culture growth at pH 6.5 was possible on a mineral salts feed containing 1800 ppm PCP. Continuous cultures grown at pH 6.7 on mineral salts feeds containing 500 and 340 mg PCP/l were especially efficient in removing PCP. Less than 4 mg PCP/l were detected in the effluent at dilution rates near washout. In batch culture studies at pH 6.5 the PCP utilization kinetics were found to be similar at low PCP concentration to those at pH 7.4 for the approximately same inoculum size. Utilization of 35 mg PCP/l was very slow at pH 6.0. Growth rates at pH 6.5 at controlled PCP concentration ranges of 5-35 and 75-115 mg/l were 0.09 h-1 and 0.05 h-1, respectively. The ability of strain ATCC 33790 to utilize PCP in mineral salts media containing naphthalene, methylnaphthalenes, and cresols was examined. Naphthalene, 1-, and 2-methylnaphthalenes at their solubility limit, and o- and m-cresols at 900-1000 mg/l prevented utilization of 80-90 mg PCP/l. PCP was rapidly removed from both commercial sand at 30°C and from clay soil at room temperature. Estimated inoculum sizes of 6.6 × 106, 6.6 × 104, and 656 cells/g were found to be effective in removing approximately half the starting amount of PCP from sand in 3, 19, and 42 h, respectively. Nearly complete disappearance of extractable PCP was observed after 1 day in clay soil inoculated with 6 × 106 cells/g

Degradation of pentachlorophenol (pcp) by arthrobacter strain atcc 33790 in biofilm culture

Abstract-Degradation of pentachlorophenol (PCP) by Arthrobacter strain ATCC 33790 naturally immobilized on glass beads in a column was studied. PCP was removed from mineral salts medium 4-5 d after inoculation of the column with PCP-acclimated cells grown in batch culture. Adherence to the glass occurred with production of extracellular polymer. The laboratory reactor operated without aseptic precaution for over 300 d employing a feed containing 12-366 mg/l PCP as the predominant carbon source. Transient studies were done with both ammonia and nitrate in the feed. With ammonia in the feed the system lost its ability to respond effectively to step increases in PCP feed concentration from 12-170 mg/l within 4 months. After 6 months, even at very low flow rate, the column was unable to efficiently remove PCP after 2 abrupt increases in hydraulic load. The presence of 120 mg/l nitrite in the effluent indicated that nitrification caused deterioration in column performance. Replacement of the ammonia in the feed with nitrate reestablished PCP removal efficiency. Effluent concentrations were typically less than 1 mg/l with 20 mg/l in the feed. In transient studies the amplitude of response to 5 step increases in feed concentration of 20-150 mg/l decreased in time from 91.5 to II mg/l. The column responded well to a step increase from 20 to 366 mg/l but was stunned following a subsequent step change from 20 to 1000 mg/l