Biodegradability and toxicity of monorhamnolipid biosurfactant diastereomers.

TitleBiodegradability and toxicity of monorhamnolipid biosurfactant diastereomers.
Publication TypeJournal Article
Year of Publication2019
AuthorsHogan, DE, Tian, F, Malm, SW, Olivares, CI, Pacheco, RPalos, Simonich, SLMassey, Hunjan, AS, Tanguay, RL, Klimecki, WT, Polt, R, Pemberton, JE, Curry, JE, Maier, RM
JournalJ Hazard Mater
Date Published2019 Feb 15

Synthetic monorhamnolipids differ from biologically produced material because they are produced as single congeners, depending on the β-hydroxyalkanoic acid used during synthesis. Each congener is produced as one of four possible diastereomers resulting from two chiral centers at the carbinols of the lipid tails [(R,R), (R,S), (S,R) and (S,S)]. We compare the biodegradability (CO respirometry), acute toxicity (Microtox assay), embryo toxicity (Zebrafish assay), and cytotoxicity (xCELLigence and MTS assays) of synthetic rhamnosyl-β-hydroxydecanoyl-β-hydroxydecanoate (Rha-C10-C10) monorhamnolipids against biosynthesized monorhamnolipid mixtures (bio-mRL). All Rha-C10-C10 diastereomers and bio-mRL were inherently biodegradable ranging from 34 to 92% mineralized. The Microtox assay showed all Rha-C10-C10 diastereomers and bio-mRL are slightly toxic according to the US EPA ecotoxicity categories with 5 min EC values ranging from 39.6 to 87.5 μM. The zebrafish assay showed that of 22 developmental endpoints tested, only mortality was observed at 120 h post fertilization; all Rha-C10-C10 diastereomers and bio-mRL caused significant mortality at 640 μM, except the Rha-C10-C10 (R,R) which showed no developmental effects. xCELLigence and MTS showed IC values ranging from 103.4 to 191.1 μM for human lung cell line H1299 after 72 h exposure. These data provide key information regarding Rha-C10-C10 diastereomers that is pertinent when considering potential applications.

Alternate JournalJ. Hazard. Mater.
PubMed ID30390580
PubMed Central IDPMC6289288
Grant ListP42 ES004940 / ES / NIEHS NIH HHS / United States
T32 ES007091 / ES / NIEHS NIH HHS / United States