Digital holographic microscopy is suitable for lipid accumulation analysis in single cells of Yarrowia lipolytica.

Digital holographic microscopy (DHM) is a label-free analytical technique for the determination of the cells' volume and their cytosolic refractive index. Here, we demonstrate the suitability of DHM for the quantification of total lipid accumulation in the oleaginous yeast Yarrowia lipolytica. Presently, microbial lipids are gaining increasing attention due to their nutritional value in feed and food applications.

Spatial monitoring of hydrolysis in a plug-flow bioreactor: a support for flexible operation?

Hydrolysis at changing hydraulic retention time, recirculation, bedding straw content in the feed, bioaugmentation and the impact of those changes on gradient formation in the liquid phase in plug-flow reactors (PFRs) was examined. The pH-value, conductivity and oxidation-reduction potential (ORP) were monitored at three spots along the PFRs to study potential correlations to process performance during a total process time of 123 weeks. The on-line monitoring showed good correlations to acidogenesis: namely, the pH and ORP to the acidification, to butyric (and lactic) acid concentration and to the acid yield.

Plug-flow hydrolysis with lignocellulosic residues: effect of hydraulic retention time and thin-sludge recirculation.

Background: Two parallel plug-flow reactors were successfully applied as a hydrolysis stage for the anaerobic pre-digestion of maize silage and recalcitrant bedding straw (30% and 66% w/w) under variations of the hydraulic retention time (HRT) and thin-sludge recirculation.

Results: The study proved that the hydrolysis rate profits from shorter HRTs while the hydrolysis yield remained similar and was limited by a low pH-value with values of 264-310 and 180-200 g kg for 30% and 66% of bedding straw correspondingly. Longer HRT led to metabolite accumulation, significantly increased gas production, a higher acid production rate and a 10-18% higher acid yield of 78 g kg for 66% of straw.

Workflow for shake flask and plate cultivations with fats for polyhydroxyalkanoate bioproduction.

Since natural resources for the bioproduction of commodity chemicals are scarce, waste animal fats (WAF) are an interesting alternative biogenic residual feedstock. They appear as by-product from meat production, but several challenges are related to their application: first, the high melting points (up to 60 °C); and second, the insolubility in the polar water phase of cultivations. This leads to film and clump formation in shake flasks and microwell plates, which inhibits microbial consumption.

Polyhydroxyalkanoate production from animal by-products: Development of a pneumatic feeding system for solid fat/protein-emulsions.

Fat-containing animal by-product streams are locally available in large quantities. Depending on their quality, they can be inexpensive substrates for biotechnological processes. To accelerate industrial polyhydroxyalkanoate (PHA) bioplastic production, the development of efficient bioprocesses that are based on animal by-product streams is a promising approach to reduce overall production costs.