Bacterial succession and co-occurrence patterns of an enriched marine microbial community during light crude oil degradation in a batch reactor.

AIMS: The aim of this study was to investigate the dynamic changes in the bacterial structure and potential interactions of an acclimatized marine microbial community during a light crude oil degradation experiment. METHODS AND RESULTS: The bacterial community effectively removed 76·49% of total petroleum hydrocarbons after 30 days, as evidenced by GC-FID and GC-MS analyses. Short-chain alkanes and specific aromatic compounds were completely degraded within the first 6 days. High-throughput sequencing of 16S rRNA gene indicated that the starting bacterial community was mainly composed by Marinobacter and more than 30 non-dominant genera. Bacterial succession was dependent on the hydrocarbon uptake with Alcanivorax becoming dominant during the highest degradation period. Sparse correlations for compositional data algorithm revealed one operational taxonomic unit (OTU) of Muricauda and an assembly of six OTUs of Alcanivorax dieselolei and Alcanivorax hongdengensis as critical keystone components for the consortium network maintenance and stability. CONCLUSIONS: This work exhibits a stabilized marine bacterial consortium with the capability to efficiently degrade light crude oil in 6 days, under laboratory conditions. Successional and interaction patterns were observed in response to hydrocarbon consumption, highlighting potential interactions between Alcanivorax and keystone non-dominant OTUs over time. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results contribute to the understanding of interactions and potential roles of specific members of hydrocarbonoclastic marine bacterial communities, which will be useful for further bioaugmentation studies concerning the associations between indigenous and introduced micro-organisms.

Slurry-phase biodegradation of weathered oily sludge waste.

We assessed the biodegradation of a typical oily sludge waste (PB401) in Mexico using several regimes of indigenous microbial consortium and relevant bioremediation strategies in slurry-phase system. Abiotic loss of total petroleum hydrocarbons (TPH) in the PB401 was insignificant, and degradation rates under the various treatment conditions ranged between 666.9 and 2168.7 mg kg(-1) day(-1) over a 15 days reaction period, while viable cell count peaked at between log(10)5.7 and log(10)7.4 cfu g(-1). Biostimulation with a commercial fertilizer resulted in 24% biodegradation of the TPH in the oily waste and a corresponding peak cell density of log(10)7.4 cfu g(-1). Addition of non-indigenous adapted consortium did not appear to enhance the removal of TPH from the oily waste. It would appear that the complexities of the components of the alkylaromatic fraction of the waste limited biodegradation rate even in a slurry system.

Biodegradation of heavy crude oil Maya using spent compost and sugar cane bagasse wastes.

Experiments were carried out to evaluate the use of some agroindustrial wastes as supports in solid state cultures for the biodegradation of crude oil Maya in static column reactors over 15-20 days periods. Spent compost and cane bagasse wastes showed superior qualities over peat moss waste as support candidates with the advantage that they contain appreciable densities of autochthonous microorganisms in the order of 10(2) cfu g(-1). Mercuric chloride (2%) was able to completely inhibit growth of these microfloras. Biodegradation was enhanced in the presence of the IMP consortium and highest when microflora from cane bagasse only was the bioaugmentation partner (180.7 mg kg(-1) day(-1)). Combination of these waste materials (3:1 ratio, respectively) was observed to significantly biodegrade the crude oil by approximately 40% in 15 days from an initial concentration of 10,000 mg kg(-1) with a four order of magnitude increase in microbial density during this period. Spent compost and cane bagasse wastes are veritable solid support candidates for use in the biodegradation of crude oil polluted systems.

Potential of Burkholderia cepacia RQ1 in the biodegradation of heavy crude oil.

The potential of Burkholderia cepacia strain RQ1 in the biodegradation of heavy crude oil (Maya) was assessed to develop an active indigenous bacterial consortium for the bioremediation of crude oil-polluted systems in Nigeria. The heavy crude oil (Maya) was utilized as sole source of carbon, attaining maximum cell densities of 10(8) cfu ml(-1) from an initial 10(5) cfu ml(-1) in 15 days. Biomass also increased with oil concentrations up to 0.8% (w/v). Growth rates ranged from 0.028 h(-1) to 0.036 h(-1) and degradation rates decreased with increasing concentrations of oil from 0.009 day(-1) to 0.004 day(-1). The quantity of oil metabolized increased significantly (P < 0.05) with increasing concentrations of oil. However, the growth of the bacterium was inhibited at crude oil concentrations beyond 6% (w/v). The pH of the culture media also dropped significantly (P < 0.05) during the 15-day test period, while the non-asphaltic fractions of the oil were significantly reduced (by about 89%) during the same period. The bacterium harbours a plasmid of about 10 kb that lacks restriction sites for the endonucleases Asp718, BamHI and PstI.