iBB

A new study from iBB, carried out within the scope of the Mobilizer Project Move2LowC, was published in the Journal of Fungi. The work describes the development, by adaptive laboratory evolution (ALE), of an evolved strain of the oleaginous yeast Rhodotorula toruloides more tolerant to the four major inhibitors present in lignocellulosic hydrolysates (LCH) (acetic acid, formic acid, hydroxymethylfurfural, and furfural). This outcome represents an advantage for the exploitation of promising lignocellulosic biomass feedstocks in bioprocesses envisaging the transition to a sustainable bio-based economy. In fact, the presence of toxic compounds in LCH is among the main barriers affecting the efficiency of lignocellulose-based fermentation processes, in particular hindering the production of intracellular lipids by oleaginous yeasts. These microbial oils are promising sustainable alternatives to vegetable oils for biodiesel production. The more protective role of the evolved strain cellular envelope (cell wall and plasma membrane) was demonstrated and the improved performance of this multi-tolerant strain for lipid production from a synthetic lignocellulosic hydrolysate medium, supplemented with those inhibitors, was confirmed. The work was led by Isabel Sá-Correia and the two first co-authors are the MSc student in Microbiology Mónica A. Fernandes, and the PhD student in Biotechnology and Biosciences Marta N. Mota. Dr. Nuno T. Faria has contributed with the lipid profile characterization.

The use of Mannosylerythritol lipids (MELs), a group of biosurfactants with excellent biochemical properties, in bioremediation in marine and terrestrial environments has been envisioned. However, knowledge regarding their ecotoxicity is limited, and the current production costs are too high to make them competitive in the surfactant market. In an effort to facilitate the use of MELs for marine bioremediation purposes, the team from 2BRG/iBB studied MELs production using seawater in medium formulation as reported on “Towards Mannosylerythritol Lipids (MELs) for Bioremediation: Effects of NaCl on M. antarcticus Physiology and Biosurfactant and Lipid Production; Ecotoxicity of MELs”, published in Journal of Marine Science and Engineering. The cells were exposed to different levels of NaCl during fermentation and the effects of increased salinity on the cells and their performance were monitored. In addition, the cells were briefly exposed to osmotic shock by introducing pure NaCl into the broth to measure their physiological responses. Although the overall effect of NaCl in the medium was negative, cells produced more lipases in these stress conditions. Furthermore, the changes triggered by osmotic shock caused changes in the cell surface and affected their hydrophobicity, reducing the levels of MELs adsorbed to the cells, which in turn led to an increase in the formation of MEL-rich beads. Marine-level salinity (3.5%) was found to be sufficient to enable the production of MELs under non-sterile conditions and to inhibit the introduction of bacterial contaminants. Finally, the toxicity levels of MELs in a model marine organism and plant model were lower than those of other biosurfactants and a commercial chemical dispersant used for bioremediation.

This publication has as first-author the (now former) PhD student Petar Kekovic of the MIT-Portugal Program in Bioengineering - and as a corresponding author Frederico Ferreira and Nuno Faria.  Additionally, the co-authors and a team from Sintef – Roman Netzer, Umer Farooq and Ariadna Szczybelski submitted a patent application for formulation of a novel MEL based oils spill response agent, reference number 117583.

Biosurfactants, particularly mannosylerythritol lipids (MELs), have excellent biochemical properties and a wide range of potential applications. However, for use at an industrial level, it is necessary to develop more sustainable production processes, both in terms of the environment and economy. In this regard, the study “Production of mannosylerythritol lipids using oils from oleaginous microalgae: two sequential microorganism culture approach” led by iBB team, with Tiago Coelho, Miguel Nascimento, Nuno Faria, Frederico Fereira, together with LNEG team, Alberto Reis and Luísa Gouveia, was just published in Microorganisms journal. It reports, for the first time, the production of MELs using oils produced from microalgae. The bio-oil was extracted from Neochloris oleoabundans and evaluated for its use as a sole carbon source or as a co-substrate strategy, using D-glucose as an additional carbon source, on Moesziomyces spp. cultures to support cell growth and induce the production of MELs. Both M. antarcticus and M. aphidis were able to grow and produce MELs using algae-derived bio-oils as carbon sources and, interestingly, there were no significant differences in productivity when oils from microalgae or vegetable oils were used as carbon sources. These results provide new perspectives for the production of MELs in systems that combine different microorganisms.

The 3rd Edition of iBB seminars will continue on the 27th May with short talks from Filipe Carvalho - "Biocatalytic Process Development: Bioprocess engineering tools and industrial application of marine biocatalysts" and Nuno Faria - "Towards biosurfactant sustainable production: novel perspectives on mannosylerythritol lipids biotechnological production and applications". Join us next monday (13h00 h, room VA.1, IST-Alameda) to learn more about Filipe's and Nuno's research at BERG.

Xylanases play a crucial role in the hydrolysis of xylan-rich hemicelluloses and have wide industrial applications in the fuel, food, feed and pulp and paper industries. Obtaining these enzymes at low cost is of paramount importance for their commercial deployment. Their production has been reported mainly from fungi, while low activity levels are typically obtained from yeast. BERG-iBB researchers in collaboration with colleagues from the National Laboratory of Energy and Geology are exploring the potential of the unconventional yeast, Moesziomyces aphidis as a xylanases producer. Brewery spent grain was found as a potent inducer for high xylanase production activity, where extracellular crude extracts presented cellulase-free xylanolytic activity. The work was published in New Biotechnology Journal.