Tuning culturing conditions towards the production of neutral lipids from lubricant-based wastewater in open mixed bacterial communities

• Type: Article in International Scientific Journal
• Date: 2018

Authors

Castro, AR (Author) Other; Silva, PTS (Author) Other; Castro, PJG (Author) Other; Alves, E (Author) Other; Domingues, MRM (Author) Other; Pereira, MA (Author) Other

Journal

Title: Water Research

Vol. 144

Pages: 532-542

ISSN: 0043-1354

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 1 Citation

Scopus - 10 Citations

Other information

Authenticus ID: P-00P-KXA

DOI: 10.1016/j.watres.2018.07.068

Abstract (EN): Production of bacterial lipid-based biofuels using inexpensive substrates, as wastes, is an emerging approach. In this work, a selective process using carbon feast-famine cycles was applied to obtain an indigenous microbial community of hydrocarbon-degrading and lipid-accumulating bacteria, using a real lubricant-based wastewater as carbon source. In the conditions applied, the enriched bacterial community, dominated by members of the genus Rhodococcus, Pseudomonas and Acinetobacter, was able to degrade almost all hydrocarbons present in the wastewater within 24 h' incubation and to accumulate, although in low levels, triacylglycerol (TAG) (<5% of cell dry weight (CDW)) and polyhydroxyalkanoates (PHA) (3.8% +/- 1.1% of the CDW) as well as an unknown lipid (29% +/- 6% of CDW), presumably a wax ester like compound. The influence of culture conditions, namely carbon and nitrogen concentrations (and C/N ratio) and cultivation time, on the amount and profile of produced storage compounds was further assessed using a statistical approach based on a central composite circumscribed design and surface response methodology. The regression analysis of the experimental design revealed that only nitrogen concentration and C/N ratio are significant for neutral lipid biosynthesis (p < 0.05). Maximum neutral lipid content, i.e. 33% (CDW basis), was achieved for the lowest carbon and nitrogen concentrations evaluated (10 g COD L-1 and 0.02 g N L-1). PHA accounted for less than 5% of CDW. In these conditions, neutral lipid content was mainly composed by TAG, about 70% (w/w). TAG precursors, namely mono-acylglycerols (MAG), diacylglycerols (DAG) and fatty acids (FA), accounted for 22% of total neutral lipids and WE for about 7%. Nevertheless, according to the applied response surface model, further improvement of neutral lipids content is still possible if even lower nitrogen concentrations are used. The fatty acids detected in TAG extracts ranged from myristic acid (C14:0) to linoleic acid (C18:2), being the most abundant palmitic acid (C16:0), stearic acid (C18:0) and oleic acid (C18:1). This study shows the feasibility of combining treatment of hydrocarbon contaminated wastewater, herein demonstrated for lubricant-based wastewater, with the production of bacterial neutral lipids using open mixed bacterial communities. This approach can decrease the costs associated to both processes and contribute to a more sustainable waste management and production of lipid-based biofuels.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11