Biosynthesis of single-cell biomass from olive mill wastewater by newly isolated yeasts

• Published in: Environmental science and pollution research international 2016-04, Vol.23 (7), p.6783-6792
• Main Authors: Arous, Fatma, Azabou, Samia, Jaouani, Atef, Zouari-Mechichi, Hela, Nasri, Moncef, Mechichi, Tahar
• Format: Article
• Language: English
• Subjects: adsorption; Ammonium; ammonium chloride; Ammonium Compounds - analysis; Ammonium Compounds - metabolism; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Biodegradation; Biodegradation, Environmental; Biological Oxygen Demand Analysis; Biomass; biomass production; Biosynthesis; By products; Candida; Candida - growth & development; Carbon; Cell growth; Chemical oxygen demand; Chloride; Earth and Environmental Science; Ecotoxicology; Effluents; Environment; Environmental Chemistry; Environmental Health; Environmental science; Fermentation; Food industries wastewaters; Glucose; Industrial Waste - analysis; inoculum; Laboratories; Lipids; Microorganisms; Nitrogen; Olea; Olea - chemistry; Olive oil; olives; phenolic compounds; Phenols; Phenols - analysis; Phenols - metabolism; Physiology; Proteins; Research Article; Saccharomycetales - growth & development; Studies; Toxicity; Waste Disposal, Fluid - methods; Waste Water - chemistry; Waste Water - microbiology; Waste Water Technology; wastewater; Water Management; Water Pollution Control; Water Purification - methods; Yeast; Yeasts
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-015-5924-2

The aim of this study was to assess the potential of newly isolated yeast strains Schwanniomyces etchellsii M2 and Candida pararugosa BM24 to produce yeast biomass on olive mill wastewater (OMW). Maximum biomass yield was obtained at 75 % (v/v) OMW, after 96 h of incubation at 30 °C and 5 % (v/v) inoculum size. The optimal carbon/nitrogen (C/N) ratio was in the range of 8:1 to10:1, and ammonium chloride was selected as the most suitable nitrogen source. Under these conditions, a maximum biomass production of 15.11 and 21.68 g L⁻¹ was achieved for Schwanniomyces etchellsii M2 and Candida pararugosa BM24, respectively. Proteins were the major constituents of yeast cells (35.9–39.4 % dry weight), lipids were 2.8–5 % dry weight, and ash ranged from 4.8 to 9.5 % dry weight. Besides biomass production, yeast strains were also able to reduce toxicity and polluting parameter levels of the spent OMW-based medium. The practical results presented show that pH rose from initial value of 5.5 to 7.24–7.45 after fermentation. Approximately 23.1–41.4 % of the chemical oxygen demand (COD) and 15.4–19.2 % of the phenolic compounds were removed. The removal of phenolic compounds was associated with their biodegradation and their partial adsorption on yeast cells.