The aim of this study was to select cultivation conditions for the production of extracellular biosurfactants from Saccharomyces cerevisiae . This yeast has been recognized due to the production of intracellular biosurfactants, and this work presented a technique to produce extracellular biosurfactants, allowing the reduction in costs with downstream processes. We studied the scale up of production in bioreactors and their effects on bioremediation in soils contaminated with biodiesel. Furthermore, we also evaluated the effects of biosurfactant addition on the adsorption of contaminants in these soils. The concentration and types of inducer (glycerol, soybean oil and diesel oil), pH levels and temperatures were studied to maximize the production through factorial designs. The - 1 results that obtained the maximum emulsifying production (6.95 UE d ) were found in the concentration of 5 g - 1 L of glycerol, a pH 5.5 and a temperature of 30 °C. In the scale up of the 5 L bioreactor, the maximum - 1 productivity of 3.85 UE d was achieved in 2 days. The addition of 0.05%, 0.1% and 0.5% of biosurfactant in soil contaminated with 20% of biodiesel for 90 days allowed a biodegradation of 56.71% with a 0.5% of biosurfactant. For all evaluated conditions, 25% of the biodegradation value should actually be attributed to the adsorption process. The addition of biosurfactants does not affect the retention of the contaminant in the soil, demonstrating that the biosurfactants improved biodegradation without interfering in the adsorption process of the contaminant in the selected soil, which is important in order to avoid influencing the movement processes of contamination plumes.

Kuhry, P., Bárta, J., Blok, D., Elberling, B., Faucherre, S., Hugelius, G., Jørgensen, C.J., Richter, A., Šantrůčková, H., Weiss, N., 2020. Lability classification of soil organic matter in the northern permafrost region. Biogeosciences 17, 361-379.

https://www.biogeosciences.net/17/361/2020/ The large stocks of soil organic carbon (SOC) in soils and deposits of the northern permafrost region are sensitive to global warming and permafrost thawing. The potential release of this carbon (C) as greenhouse gases to the atmosphere does not only depend on the total quantity of soil organic matter (SOM) affected by warming and thawing, but it also depends on its lability (i.e., the rate at which it will decay). In this study we develop a simple and robust classification scheme of SOM lability for the main types of soils and deposits in the northern permafrost region. The classification is based on widely available soil geochemical parameters and landscape unit classes, which makes it useful for upscaling to the entire northern permafrost region. We have analyzed the relationship between C content and C-CO production rates of soil samples in two different types 2 of laboratory incubation experiments. In one experiment, ca. 240 soil samples from four study areas were ∘ incubated using the same protocol (at 5 C, aerobically) over a period of 1 year. Here we present C release rates measured on day 343 of incubation. These long-term results are compared to those obtained from short-term ∘ incubations of ca. 1000 samples (at 12 C, aerobically) from an additional three study areas. In these experiments, C-CO production rates were measured over the first 4 d of incubation. We have focused our 2 - 1 - 1 analyses on the relationship between C-CO production per gram dry weight per day (µgC-CO gdw d ) and 2 2 C content (%C of dry weight) in the samples, but we show that relationships are consistent when using C∕ N - 1 - 1 3 ratios or different production units such as µgC per gram soil C per day (µgC-CO gC d ) or per cm of soil 2 - 3 - 1 per day (µgC-CO cm d ). C content of the samples is positively correlated to C-CO production rates but 2 2 explains less than 50 %of the observed variability when the full datasets are considered. A partitioning of the data into landscape units greatly reduces variance and provides consistent results between incubation experiments. These results indicate that relative SOM lability decreases in the order of Late Holocene eolian deposits to alluvial deposits and mineral soils (including peaty wetlands) to Pleistocene yedoma deposits to C- enriched pockets in cryoturbated soils to peat deposits. Thus, three of the most important SOC storage classes in the northern permafrost region (yedoma, cryoturbated soils and peatlands) show low relative SOM lability. Previous research has suggested that SOM in these pools is relatively undecomposed, and the reasons for the observed low rates of decomposition in our experiments need urgent attention if we want to better constrain the magnitude of the thawing permafrost carbon feedback on global warming.

Kutchko, B., Sanguinito, S., Natesakhawat, S., Cvetic, P., Culp, J.T., Goodman, A., 2020. Quantifying pore scale and matrix interactions of SCCO with the Marcellus shale. Fuel 266, 116928. 2

http://www.sciencedirect.com/science/article/pii/S001623611932321X