Assessment of Bilge Water Degradation by Isolated Citrobacter sp. and Two Indigenous Strains and Identification of Organic Content by GC-MS

Abstract

Bilge water is oily saline wastewater accumulated on the hull at the bottom of a vessel, generated from leakage from pipes and engines and wash-down freshwater containing cleaning solvents. The present study focused on isolating microorganisms from oil-contaminated sites and indigenous species from raw bilge water and assessment of their ability to biodegrade bilge water. Using phenanthrene as a carbon source Citrobacter species was isolated from oil-contaminated sites and its optimum growth condition was found. The results indicated significant tolerance of the bacterium which presented great biodegradation ability for the tested carbon source. At high salinity (33 g L−1 of NaCl), sufficient phenathrene removal was achieved (81%), whereas variation of pH from 5 to 10 did not affected the survival of the microorganism. Regarding the effect of temperature and nutrients, Citrobacter sp. was better adapted at 30 °C, while lack of nutrients presented a negative impact on its growth. Halomonas and Exiguobacterium sp. were isolated from real bilge water using phenanthrene and phenol as a carbon source. The isolated strains independently exposed to high and low range bilge water pointed out around 83% and 53% chemical oxygen demand (COD) removal, respectively. Analysis of untreated bilge water by gas chromatography-mass spectrometry (GC-MS) was carried out, and the results confirmed the presence of organic compounds having a high similarity with Heptane, N-hexadecanoic acid, Methyl isobutyl Ketone and 1-butoxy-2-propanol. Chromatographic analysis of treated bilge water after exposure to isolated strains indicated the existence of new compounds. These metabolites presented high similarity with N-hexadecanoic, methyl ester, N-hexadecanoic and Octadecanoic acid methyl ester.

Four Novel Caudoviricetes Bacteriophages Isolated from Baltic Sea Water Infect Colonizers of Aurelia aurita

“…Pseudomonas species play a critical role in the marine nitrogen cycle, as they are capable of nitrogen fixation and denitrification [ 107 ]. While less is known about Citrobacter -specific ecological roles in marine environments, it can cycle degrading organic matter [ 108 ]. Both Pseudomonas and Citrobacter are opportunistic pathogens that can cause infections in marine multicellular organisms [ 103 , 104 , 109 ].…”

“…Consequently, virulent phages infecting those bacteria might disturb the ecosystem and metaorganism homeostasis. Bacteriophages that infect Pseudomonas and Citrobacter have been identified in marine environments, and they may play essential roles in regulating the abundance and activity of these bacteria [ 82 , 108 , 109 ]. For example, bacteriophages that infect Pseudomonas can control its population size and limit its ability to degrade organic matter, significantly impacting nutrient cycling in marine ecosystems [ 112 , 113 ].…”

Four novel Caudoviricetes bacteriophages isolated from Baltic Sea water infect colonizers of Aurelia aurita

“…While less is known about Citrobacter-specific ecological roles in marine environments, it can cycle degrading organic matter (Gatidou et al, 2022). Both Pseudomonas and Citrobacter are opportunistic pathogens and can cause infections in marine multicellular organisms (Lü et al, 2011;Thanigaivel et al, 2015;Tkachenko et al, 2016).…”

“…Consequently, lytic phages infecting those bacteria might disturb the ecosystem and metaorganism homeostasis. Bacteriophages that infect Pseudomonas and Citrobacter have been identified in marine environments, and they may play essential roles in regulating the abundance and activity of these bacteria (Gatidou et al, 2022;Thanigaivel et al, 2015;Zhang et al, 2022). For example, bacteriophages that infect Pseudomonas can control its population size and limit its ability to degrade organic matter, [30] significantly impacting nutrient cycling in marine ecosystems (Knezevic et al, 2011;Wommack & Colwell, 2000).…”