Recently, the enzyme family of oleate hydratases (OHs: EC 4.2.1.53) has gained increasing scientific and economic interest, as these FAD‐binding bacterial enzymes do not require cofactor recycling and possess high thermal and pH stability. Their products, hydroxy fatty acids, are used in specialty chemical applications including surfactant and lubricant formulations. The “oleate hydratase engineering database”, established by Schmid et al. (2017), divides all OHs into 11 families (HFam1 to 11). To date, only two crystal structures of homodimeric OHs from the families HFam2 and HFam11 have been reported. In this study, we biophysically characterized an OH belonging to the HFam3 family, originating from the marine bacterium Rhodococcus erythropolis, for the first time. The crystal structure revealed that this new OH (OhyRe) surprisingly is a monomer in its active form. This particular feature provides new avenues for enzyme engineering and recycling through immobilization.

A novel aerobic, psychrotolerant marine bacterium was isolated at 4 6C from seawater samples collected from Spitzbergen in the Arctic. The strain was a polar-flagellated, Gram-negative bacterium that grew optimally at 10-15 6C and pH 7-8 in media containing 2-3 % NaCl (w/v), using various carbohydrates and organic acids as substrates. The main fatty acid components included 16 : 0 (12.7 % of total fatty acids), straight-chain saturated fatty acid methyl ester (FAME) and 16 : 1v7c (40.2 %) monounsaturated FAME. Phylogenetic analysis revealed a close relationship (99 % 16S rRNA gene sequence similarity) between the novel isolate and Pseudoalteromonas elyakovii KMM 162T and some other species of the genus Marine Pseudomonas-like bacteria comprise several related genera, including Alteromonas, Marinomonas, Pseudoalteromonas, Moritella, Marinobacter, Psychrobacter, Colwellia, Shewanella, Halomonas and several others. Classification of these aerobic heterotrophic micro-organisms from the marine environment remains difficult and time-consuming due to their phenotypic diversity and the absence of robust chemotaxonomic markers. Fortunately, phylogenetic information based on 16S rRNA gene sequences is useful in classifying and identifying micro-organisms belonging to previously poorly defined taxa (Ivanova et al., 2000).The genus Pseudoalteromonas, originally called Alteromonas, includes non-pigmented, Gram-negative, heterotrophic, aerobic, polar-flagellated species of marine bacteria that have DNA G+C contents ranging from 38 to 50 mol%. These characteristics differentiate this bacterial group from the previously described genus Pseudomonas. Since Baumann et al. (1972) proposed the genus Alteromonas in 1972, several species have been assigned to this genus. A recent revision of the genera based on phylogenetic analysis (Gauthier et al., 1995) divided the genus Alteromonas into two genera, Pseudoalteromonas and Alteromonas.Pseudoalteromonas is one of the largest genera within the class Gammaproteobacteria and currently comprises more than 30 species (Ivanova et al., 2004). These bacteria play an important role in marine environments owing to their abundance and high metabolic activities. Pseudoalteromonads are highly capable of surviving in nutrient-poor marine environment by adjustment of their biochemical pathways and production of a wide variety of metabolites, including biologically active compounds and enzymes (Ivanova et al., 2003).In this study, a novel aerobic bacterium was isolated from ice and seawater samples obtained from the area of Spitzbergen in the Arctic. This novel isolate was found to belong to the genus Pseudoalteromonas. Taxonomic and physiological analysis of this isolate demonstrated that it represents a novel species of the genus Pseudoalteromonas.Arctic sea ice and seawater samples were collected from Spitzbergen, Norway, and transported to the laboratory at an ambient temperature of 10 u C. A 1 ml aliquot of each of the 50 liquid samples was incubated at 4 u C in a complex marine aerobic liquid m...

Microalgae are capable of producing up to 70% w/w triglycerides with respect to their dry cell weight. Since microalgae utilize the greenhouse gas CO2, they can be cultivated on marginal lands and grow up to ten times faster than terrestrial plants, the generation of algae oils is a promising option for the development of sustainable bioprocesses, that are of interest for the chemical lubricant, cosmetic and food industry. For the first time we have carried out the optimization of supercritical carbon dioxide (SCCO2) mediated lipid extraction from biomass of the microalgae Scenedesmus obliquus and Scenedesmus obtusiusculus under industrrially relevant conditions. All experiments were carried out in an industrial pilot plant setting, according to current ATEX directives, with batch sizes up to 1.3 kg. Different combinations of pressure (7–80 MPa), temperature (20–200 °C) and CO2 to biomass ratio (20–200) have been tested on the dried biomass. The most efficient conditions were found to be 12 MPa pressure, a temperature of 20 °C and a CO2 to biomass ratio of 100, resulting in a high extraction efficiency of up to 92%. Since the optimized CO2 extraction still yields a crude triglyceride product that contains various algae derived contaminants, such as chlorophyll and carotenoids, a very effective and scalable purification procedure, based on cost efficient bentonite based adsorbers, was devised. In addition to the sequential extraction and purification procedure, we present a consolidated online-bleaching procedure for algae derived oils that is realized within the supercritical CO2 extraction plant.

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