Transformation of Brewery Subproducts into Valuable Biomass Using Mixotrophic Culture of Chlorella pyrenoidosa and Associated Bacteria

Abstract

To develop a biorefinery concept applied in the brewery industry, Chlorella pyrenoidosa and a consortium of associated bacteria were cultivated mixotrophically in a continuous photobioreactor using brewery low-value subproducts as an integrative process. Beer production residues were biochemically characterized to assess the most promising options to be used as a nutrient source for microalgal cultivation. Due to its physical and chemical properties, pre-treated weak wort was used to prepare an organic complex culture medium for microalgal biotransformation. Filtration and nitrogen supplementation were necessary to improve nutrient removal and biomass productivity. Maximal removal of nitrate and phosphate obtained were 90% and 100% respectively. Depending on operation conditions, total carbohydrates depuration ranged from 50-80%. The initial concentration of total carbohydrates of the weak wort must be adjusted to 2-4g/L to maintain a stable equilibrium between microalgal and bacterial growth. The biochemical composition of produced biomass varied depending on the cultivation conditions as well as on its final use. Upon continuous mixotrophic conditions evaluated in this study, C. pyrenoidosa was composed mainly of carbohydrates and protein.

Remediation of Brewery Wastewater and Reuse for β-Glucans Production by Basidiomycete Fungi

“…1515.90 mg L -1 for total organic carbon (TOC) [42], 24-451 mg L -1 for total nitrogen, 5-44.33 mg L -1 for NH3-N [2,5,6,43,44], 0.50 MgNO3-mg L -1 for nitrate [42], 33.25 mg L -1 of nitrate nitrogen (NO3-N), <0.1 mg L -1 for nitrite nitrogen (NO2-N) [44], 0.5-600 mg L -1 for total phosphorus [2,5,[42][43][44], 10-50 mg L -1 for phosphates [5,6], 8.6 mg L -1 orthophosphate 7 (PO43-P) [44], 240.68 MgSO4-mg L -1 for sulfate [42], 190-3170 mg L -1 CaCO3 for Al [2], 500 mg L -1 for suspended solid (SS) [6], 3232 mg L -1 for dissolved solids [42], 63.62 mg L -1 for total solids (TS), and 0.264 mg L -1 for volatile solids (VS) [43], 160 NTU (Nephelometric Turbidity Units: 3 NTU = 1 ppm SiO2) for turbidity [42], and pH 4.5-12 [2,5,6,[43][44][45]. BW is considered a highly pollutant due to the high levels of organic carbon and other pollutants [1].…”

“…The differences in sugar consumption among the species might rely on the media sugar profile or because of rich media use. Some microorganisms show different affinity levels to maltose, glucose, galactose, and fructose, needing different retention times to consume the sugars on the substrate [42]. This carbohydrate control is important once it can show the amount of sugar that was not fermented by the fungi, reducing the process efficiency and/or changing the product quality [62].…”

“…Giraldo et al [42] studied the transformation of brewery subproducts into valuable biomass using Chlorella pyrenoidosa and associated bacteria. Depending on operation conditions, total carbohydrate depuration ranged from 50 -80% [42]. Wang et al [43] studied the cultivation of the microalga Chlorella sp.…”

“…BW has been successfully described as feedstock for yeast and microalga presenting encouraging results [87]. Giraldo et al [42] studied the transformation of brewery subproducts into valuable biomass using Chlorella pyrenoidosa and associated bacteria. The authors reported a maximal removal of nitrate and phosphate between 90% and 100%, respectively, after 6 days of cultivation.…”

Metabolic response of Botryococcus braunii to high bicarbonate dosages and other conditions: analysis of photosynthetic performance, productivity, and lipidomic profile

“…For nutrient consumption, each culture was sampled and centrifuged (20,000 × g, 5 min). The N and P content remaining in the cell free supernatant were analyzed spectrophotometrically via the salicylic acid method and ascorbic acid method, respectively, as described elsewhere (Giraldo et al 2020).…”