Genome-Guided Characterization of Ochrobactrum sp. POC9 Enhancing Sewage Sludge Utilization—Biotechnological Potential and Biosafety Considerations

Abstract

Sewage sludge is an abundant source of microorganisms that are metabolically active against numerous contaminants, and thus possibly useful in environmental biotechnologies. However, amongst the sewage sludge isolates, pathogenic bacteria can potentially be found, and such isolates should therefore be carefully tested before their application. A novel bacterial strain, Ochrobactrum sp. POC9, was isolated from a sewage sludge sample collected from a wastewater treatment plant. The strain exhibited lipolytic, proteolytic, cellulolytic, and amylolytic activities, which supports its application in biodegradation of complex organic compounds. We demonstrated that bioaugmentation with this strain substantially improved the overall biogas production and methane content during anaerobic digestion of sewage sludge. The POC9 genome content analysis provided a deeper insight into the biotechnological potential of this bacterium and revealed that it is a metalotolerant and a biofilm-producing strain capable of utilizing various toxic compounds. The strain is resistant to rifampicin, chloramphenicol and β-lactams. The corresponding antibiotic resistance genes (including blaOCH and cmlA/floR) were identified in the POC9 genome. Nevertheless, as only few genes in the POC9 genome might be linked to pathogenicity, and none of those genes is a critical virulence factor found in severe pathogens, the strain appears safe for application in environmental biotechnologies.

Identification and Characterization of the First Virulent Phages, Including a Novel Jumbo Virus, Infecting Ochrobactrum spp.

“…LM19 [53], Ochrobactrum sp. POC9 [11], Paracoccus alcaliphilus JCM 7364 [57], Paracoccus aminophilus JCM 7686 [58], Pseudomonas aeruginosa PAO1161 [59], Pseudomonas sp. LM7 [60], Psychrobacter sp.…”

“…are non-fermenting, aerobic, Gram-negative bacteria of the Alphaproteobacteria class, which are frequently isolated from a variety of environmental (water, soil, and plants) and clinical (animals and human) samples [1][2][3][4][5][6][7][8]. Many strains originating from various natural and anthropogenically-shaped environments, such as wastewater or polluted soil, exhibit an extensive repertoire of enzymatic properties, which are attractive from a biotechnological perspective [9][10][11]. The reported metabolic properties include the ability to utilize many pollutants (e.g., pesticides, herbicides, and dimethylamine) and the biotransformation of toxic metal ions [12][13][14][15].…”

“…For their identification, the previously characterized strain Ochrobactrum sp. POC9 (which efficiently enhances the utilization of sewage sludge, thereby increasing the effectiveness of biogas production) was used [11,23]. This strain was isolated from the wastewater treatment plant (WWTP) "Czajka" in Warsaw (Poland).…”

“…This strain was isolated from the wastewater treatment plant (WWTP) "Czajka" in Warsaw (Poland). It is a biofilm-forming and metal-resistant strain with lipolytic, proteolytic, cellulolytic, and amylolytic activities useful during the aerobic hydrolysis of complex organic compounds, such as lipids, proteins, and polysaccharides [11]. This study initially aimed to determine whether there are viruses in WWTPs that may act as natural bactericidal agents for the POC9 strain, which may limit its efficiency as a biogas production enhancer.…”

Intensification of biogas production using various technologies: A review

“…Methane fermentation consists of four biological and chemical stages, which engage particular groups of mutually interacting microorganisms (Figure ) . AD is a slow process, and microorganisms need at least 3 weeks to adapt to a new environment whenever a substrate, temperature, or other environmental factors change .…”