Isolation and Characterization of Ochrobactrum tritici for Penicillin V Potassium Degradation

Abstract

Substantial concentrations of penicillin V potassium (PVK) have been found in livestock manure, soil, and wastewater effluents, which may pose potential threats to human health and contribute to the emergence of penicillin-resistant bacterial strains. In this study, bacterial strains capable of degrading PVK were isolated from sludge and characterized. Strain X-2 was selected for biodegradation of PVK. Based on morphological observations and 16S rRNA gene sequencing, strain X-2 was identified as an Ochrobactrum tritici strain. To enhance the PVK degradation ability of PVK, a whole-cell biodegradation process of Ochrobactrum tritici X-2 was established and optimized. In the whole-cell biodegradation process, the optimal temperature and pH were 30°C and 7.0, respectively. Under the optimized conditions, the degradation rate using 0.5 mg/ml PVK reached 100% within 3 h. During biodegradation, two major metabolites were detected: penicilloic acid and phenolic acid. The present study provides a novel method for the biodegradation of PVK using Ochrobactrum tritici strains, which represent promising candidates for the industrial biodegradation of PVK.IMPORTANCE Substantial concentrations of penicillin V potassium (PVK) have been found in the environment, which may pose potential threats to human health and contribute to the emergence of penicillin-resistant bacterial strains. In this study, antibiotic-degrading bacterial strains for PVK were isolated from sludge and characterized. Ochrobactrum tritici was selected for the biodegradation of PVK with high efficiency. To enhance its PVK degradation ability, a whole-cell biodegradation process was established and optimized using Ochrobactrum tritici The degradation rate with 0.5 mg/ml PVK reached 100% within 3 h. The potential biodegradation pathway was also investigated. To the best of our knowledge, the present study provides new insights into the biodegradation of PVK using an Ochrobactrum tritici strain, a promising candidate strain for the industrial biodegradation of β-lactam antibiotics.

Keywords: Ochrobactrum tritici; antibiotic; bacterial residue; biodegradation; biotransformation; penicillin V potassium.

FIG 1

Morphological features of strain X-2. (A) Colony morphology of strain X-2; (B) morphological characteristics of strain X-2 under light microscopy.

FIG 2

Phylogenetic analysis of strain X-2 in the neighbor-joining tree.

FIG 3

(A) Effect of different carbon sources on the growth of Ochrobactrum tritici X-2. The fermentation process was conducted at 30°C and pH 7.0 for 24 h. (B) Effect of nitrogen sources on the growth of strain Ochrobactrum tritici X-2. The reactions were conducted at 30°C and pH 7.0 for 24 h. Data are the means from three experiments, and error bars represent standard deviations.

FIG 4

(A) Effect of temperature on the growth of Ochrobactrum tritici X-2. The fermentation process was conducted at pH 7.0 for 24 h by varying temperature from 15 to 40°C. (B) Effect of pH on the growth of strain Ochrobactrum tritici X-2. The reactions were conducted at 30°C for 24 h by using pH values from 4.0 to 10.0. Data are the means from three experiments, and error bars represent standard deviations.

FIG 5

(A) Effect of temperature on the biodegradation of PVK by Ochrobactrum tritici X-2 whole-cell biotransformation. The reactions were conducted at pH 7.0 for 3 h by varying the temperature from 15 to 40°C. (B) Effect of pH on the biodegradation of PVK by Ochrobactrum tritici X-2 whole-cell biotransformation. The reactions were conducted at 30°C for 24 h by varying the pH value from 5.0 to 9.0. Data the means from three experiments, and error bars represent the standard deviations.

FIG 6

HPLC analysis of biodegradation of PVK by Ochrobactrum tritici X-2.

FIG 7

Biodegradation profiles of PVK by Ochrobactrum tritici X-2.