Low chemical concentration and pH as factors limiting the success of inoculation to enhance biodegradation

Abstract

A strain of Pseudomonas that mineralized 1 microgram of p‐nitrophenol (PNP) per milliliter in culture failed to mineralize the compound in nonsterile or sterile lake water. The bacterium did not act on PNP at the pH of the lake water (pH 8.0) or in culture medium at the same pH, although it did mineralize PNP when added to sterile lake water samples adjusted to pH 7.0. A second strain of Pseudomonas that grew and mineralized 1 μg PNP/ml in culture at pH 8.0 and in sterile lake water at pH 7.0 neither mineralized nor grew on PNP in sterile lake water at pH 8.0. A third strain of Pseudomonas grew on and mineralized 1 μg PNP/ml in sterile lake water at pH 8.0 but failed to enhance mineralization when added to nonsterile lake water at that pH. Corynebacterium sp. grew on and mineralized 1 μg PNP/ml in culture medium and in sterile lake water, and its inoculation into nonsterile lake water greatly reduced the time for the mineralization of 1.0 and 0.1 μg PNP/ml. The inoculation of nonsterile lake water with Corynebacterium sp., which mineralized 26 and 17 ng PNP/ml in culture, resulted in a biphasic transformation of 26 and 16 ng PNP/ml. Only the initial phase was more rapid than in uninoculated lake water. Inoculation of Corynebacterium sp. into sewage markedly shortened the time for extensive mineralization of 100 ng but not of 26 and 16 ng PNP/ml. We suggest that microorganisms that are able to degrade chemicals in culture may not do so when introduced into natural environments because of unfavorable pH or the organisms' inability to readily use compounds that are present at low concentrations.

Characterization of the biodegradation, bioremediation and detoxification capacity of a bacterial consortium able to degrade the fungicide thiabendazole

“…Each value is the mean of three replicates ± the standard deviation Table 1 The dissipation kinetic parameters for TBZ dissipation in the soil samples bioaugmented with 5, 50 and 50 mg kg The dissipation data were fitted to the single first order kinetics model and the biphasic model hockey stick and model best fitted to data is shown for each treatment Biodegradation benzyl moiety, possibly as catechol, which was effectively mineralized by the bacterial consortium as demonstrated in the present study. Previous studies have shown that lab-scale liquid culture experiments could be useful to define the range of conditions in which pesticide-degrading bacteria will be active in environmental matrices (Chatterjee et al 1982;Zaidi et al 1988). By doing so, we showed that our consortium was able to effectively degrade TBZ in a range of pH between 4.5 and 7.5, while its degradation capacity was completely halted at highly alkaline conditions (pH 9.0).…”

Biodegradability of Metronidazole, Olaquindox, and Tylosin and Formation of Tylosin Degradation Products in Aerobic Soil–Manure Slurries

“…First, the temperature was higher than typical in Denmark, which most likely leads to higher biodegradation rates than would occur in nature. Second, the concentration of the antibiotics was higher than expected in the environment, which, as discussed by several authors (Nyholm and Ingerslev, 1997;Zaidi et al, 1988), may lead to arti"cially large amounts of degraders in the test systems and hence to overestimation of biodegradation rates. The third major di!erence from the natural situation was the large amount of water in the test systems, which was used to enable the concentration of the test compounds to be followed using HPLC analysis.…”

Inoculation of microorganisms to enhance biodegradation of phenolic compounds in industrial wastewater: Isolation and identification of three-indigenous bacterial strains.

“…strain Z-4 (17). This is a mutant of a strain originally isolated from Cayuga Lake water, Ithaca, NY, U.S.A., and is resistant to 10 dig of kasugamycin, 100, tg of streptomycin, and 25 ug of spectinomycin per milliliter (Zaidi et al, 1988). The population of this bacterium in water samples was determined by the drop plate method (7) on 0.3% Trypticase soy agar containing the three antibiotics at the indicated concentrations.…”