No abstract

The production of biodiesel has notably increased over the past decade. Currently, plant oil is the main feedstock for biodiesel production, but, due to concerns related to the competition with food production, alternative oil feedstocks have to be found. Oleaginous yeasts are known to produce high amounts of lipids, but no integrated process from microbial fermentation to final biodiesel production has reached commercial realization yet due to economic constraints. Therefore, growth and lipid production of red yeastRhodotorula glutiniswas tested on low-cost substrates, namely, wastewaters from potato, fruit juice, and lettuce processing. Additionally, the production of carotenoids as high-value by-products was examined. All evaluated wastewaters met the general criteria for microbial lipid production. However, no significant increase in lipid content was observed, probably due to lack of available carbon in wastewaters from fruit juice and lettuce processing, and excess of available nitrogen in potato processing wastewater, respectively. During growth on wastewaters from fruit juice and lettuce processing the carotenoid content increased significantly in the first 48 hours. The relations between carbon content, nitrogen content, and carotenoid production need to be further assessed. For economic viability, lipid and carotenoid production needs to be increased significantly. The screening of feedstocks should be extended to other wastewaters.

Starch containing wastewaters from the food and feed industry have been identified as potential cheap carbon sources for the production of microbial lipids. Due to its high potential lipid content the oleaginous yeast Rhodotorula glutinis is often used for fermentations in this field. Moreover it is investigated in the context of microbial carotenoid production, which also requires a cheap source of carbon. Thus, the ability of R. glutinis (ATCC 15125 TM) to degrade and utilize soluble starch for the production of lipids has been assessed in this study. While glucose and fructose were readily consumed from the medium, starch was only slightly reduced in one treatment. The yield of fatty acid methyl esters (FAME) was graduated corresponding to the initial sugar contents, with the highest FAME yield (1.5 g•L −1) at the highest initial sugar content. In the treatment that contained starch as single carbon source, no FAME production was realized. Accordingly, if starchy wastewaters should be used for microbial cultivation with R. glutinis, an enzymatic or chemical pretreatment for starch hydrolysis should be applied, to increase the availability of this carbon source.

In two experiments, we tested the hypothesis that guilt feelings would elevate the probability of making a false confession. In Experiment 1 (N = 146), a confederate induced guilt feelings by asking participants to cheat on a task. The experimenter then falsely accused participants of having pressed a forbidden key, causing a computer crash. In Experiment 2 (N = 108), a confederate was punished every time participants could not answer a quiz question. The confederate later cheated in a game and asked participants to take the blame. In Experiment 1, 100 participants (68.5%) falsely confessed to pressing the key. In Experiment 2, 39 participants (36.1%) falsely confessed to cheating. Guilt manipulations had no effect on false confession rates. When exploring the effect of guilt feelings, five of eight tests were statistically non-significant. As yet, there is insufficient evidence to argue that guilt feelings are a major determinant of false confessions.

Inspired by theories of prosocial behavior, we tested the effect of relationship status and incentives on intended voluntary blame-taking in two experiments (Experiment 2 was pre-registered). Participants (NE1 = 211 and NE2 = 232) imagined a close family member, a close friend, or an acquaintance and read a scenario that described this person committing a minor traffic offense. The person offered either a monetary, social, or no incentive for taking the blame. Participants indicated their willingness to take the blame and reasons for and against blame-taking. Overall, a sizable proportion of participants indicated to be willing to take the blame (E1: 57.8%; E2: 34.9%). Blame-taking rates were higher for family members than close friends or acquaintances in both experiments, as expected. Unexpectedly, there was no difference between a close friend and an acquaintance in Experiment 2. Social incentives did not have an effect on voluntary blame-taking in either experiment. Neither did we find an interaction between relationship status and incentives. The results highlight the importance of kin relationships in the context of voluntary blame-taking.