microorganisms Article Wastewater from the Edible Oil Industry as a Potential Source of Lipase- and Surfactant-Producing Actinobacteria Pamela Welz , Gustav Swanepoel, Shandré Weels and Marilize Le Roes-Hill *   Citation: Welz, P.; Swanepoel, G.; Weels, S.; Le Roes-Hill, M. Wastewater from the Edible Oil Industry as a Potential Source of Lipase- and Surfactant-Producing Actinobacteria. Microorganisms 2021, 9, 1987. https://doi.org/10.3390/ microorganisms9091987 Academic Editor: Alla Lapidus Received: 30 August 2021 Accepted: 10 September 2021 Published: 18 September 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Applied Microbial and Health Biotechnology Institute, Cape Peninsula University of Technology, P.O. Box 1906, Bellville 7535, South Africa; WelzP@cput.ac.za (P.W.); swangustav@gmail.com (G.S.); shandrelavern@gmail.com (S.W.) * Correspondence: Leroesm@cput.ac.za; Tel.: +27-21-953-8499 Abstract: Wastewaters generated from various stages of edible oil production in a canola processing facility were collected with the aim of determining the presence of lipase-producing actinobacteria of potential industrial significance. The high chemical oxygen demand (COD) readings (up to 86,700 mg L −1 in some samples) indicated that the wastewater exhibited the nutritional potential to support bacterial growth. A novel approach was developed for the isolation of metagenomic DNA from the oil-rich wastewater samples. Microbiota analysis of the buffer tank and refinery condensate tank wastewater samples showed a dominance of Cutibacterium acnes subsp. defendens, followed by a limited number of other actinobacterial genera, indicating the presence of a highly specialized actinobacterial population. Cultured isolates with typical actinobacterial morphology were analyzed for their ability to produce lipases and biosurfactants. Two strains, designated as BT3 and BT4, exhibited the highest lipase production levels when grown in the presence of tributyrin and olive oil (1.39 U mg −1 crude protein and 0.8 U mg −1 crude protein, respectively) and were subsequently definitively identified by genome sequencing to be related to Streptomyces albidoflavus. Cultivation of the strains in media containing different types of oils did not markedly increase the level of enzyme production, with the exception of strain BT4 (1.0 U mg −1 crude protein in the presence of peanut oil). Genome sequencing of the two strains, BT3 and BT4, revealed the presence of a range of lipase and esterase genes that may be involved in the production of the enzymes detected in this study. The presence of gene clusters involved in the production of biosurfactants were also detected, notably moreso in strain BT3 than BT4. Keywords: actinobacteria; biosurfactants; edible oil; microbiota; lipase; wastewater 1. Introduction Over the past one and a half centuries, numerous publications have focused on the enzyme lipase (triacylglycerol-acyl-hydrolase; EC 3.1.1.3). This ubiquitous enzyme is produced by animals, plants, and microorganisms and catalyzes the hydrolysis of glycerol-esters (notably long-chain acylglycerols vs. short-chain acylglycerols hydrolyzed by esterases) for the release of diacylglycerols, monoacylglycerols, and free fatty acids [1–3]. It is due to their ability to catalyze these reactions and their high degree of stereospecificity that they have found application in a wide range of industries: cosmetics, pharmaceuticals, detergents, food, leather, textile, paper, and biodiesel [3]. It is often found that organisms with the ability to produce lipases also produce surface active compounds [4]. These amphipathic compounds show activity at interfaces by lowering the tension between them: surfactants reduce surface tension at the air–water interface, while emulsifiers reduce the surface tension between two immiscible liquids. Lipases are known to facilitate the action of surfactants, and it is expected that some microorganisms isolated from oil-contaminated environments would have the ability to produce both lipases and surfactants [1,5]. With the need for more ‘green’ processes to drive the global bioeconomy, as well as consumer Microorganisms 2021, 9, 1987. https://doi.org/10.3390/microorganisms9091987 https://www.mdpi.com/journal/microorganisms