Fungi have the ability to transform organic materials into a rich and diverse set of useful products and provide distinct opportunities for tackling the urgent challenges before all humans. Fungal biotechnology can advance the transition from our petroleum-based economy into a bio-based circular economy and has the ability to sustainably produce resilient sources of food, feed, chemicals, fuels, textiles, and materials for construction, automotive and transportation industries, for furniture and beyond. Fungal biotechnology offers solutions for securing, stabilizing and enhancing the food supply for a growing human population, while simultaneously lowering greenhouse gas emissions. Fungal biotechnology has, thus, the potential to make a significant contribution to climate change mitigation and meeting the United Nation's sustainable development goals through the rational improvement of new and established fungal cell factories. The White Paper presented here is the result of the 2nd Think Tank meeting held by the EUROFUNG consortium in Berlin in October 2019. This paper highlights discussions on current opportunities and research challenges in fungal biotechnology and aims to inform scientists, educators, the general public, industrial stakeholders and policymakers about the current fungal biotech revolution.

The contribution of CO2 to cell material synthesis in Thiobacillus novellus under nutrient-limited conditions was estimated by comparing 14Co2 uptake rates of steady-state autotrophic cultures with that of heterotrophic and mixotrophic cultures at a given dilution rate. Under heterotrophic conditions, some 13% of the cell carbon was derived from C02; this is similar to the usual anaplerotic CO2 fixation in batch cultures of heterotrophic bacteria. Under mixotrophic conditions, the contribution of CO2 to cell material synthesis increased with increasing S2032-to-glucose ratio in the medium inflow; at a ratio of 10, ca. 32% of the cell carbon was synthesized from CO2. We speculate that the use of CO2 as carbon source, even when the glucose provided is sufficient to fulfill the biosynthetic needs, may augment the growth rate of the bacterium under such nutrient-limited conditions and could therefore be of survival value in nature. Some of the CO2 assimilated was excreted into the medium as organic compounds under all growth conditions, but in large amounts only in autotrophic environments as very low dilution rates.

In a mixotrophic environment, Thiobacillus novellus concurrently utilized glucose and thiosulfate but showed no stimulation of growth rate or yield. In most mixotrophic environments examined, the growth rate was lower than the heterotrophic growth rate, the extent of tbe decrease depending on the concentration and relative proportion of thiosulfate and glucose in the medium. Both thiosulfate and glucose were degraded to their most oxidized products in mixotrophic medium, yet the biomass production in this medium was comparable to that found in heterotrophic medium containing glucose alone at the corresponding concentration. It was postulated that in mixotrophic medium the oxidation of thiosulfate, glucose, or partially that of both was uncoupled from energy generation. These results differ in many respects from those reported earlier by LeJohn et al. (J. Bacteriol. 94: 1484(J. Bacteriol. 94: -1491(J. Bacteriol. 94: , 1967; experiments designed to exactly duplicate some of the growth conditions employed by these workers did not resolve the discrepancy.Thiobacillus novellus, like other facultative chemolithotrophs, possesses the unique potential for autotrophic as well as heterotrophic growth. Since in nature these bacteria are likely to encounter the heterotrophic and autotrophic growth substrates simultaneously, it is of considerable interest to determine whether they are capable of mixotrophic growth, i.e., growth during which organic and inorganic substrates are concurrently utilized (4, 11). Mixotrophy in T. novellus has been previously studied by LeJohn et al. (2). These workers showed that the presence of glucose in the medium caused a complete inhibition of thiosulfate utilization by this bacterium and that the rates of growth and glucose utilization in thiosulfate-glucose medium were identical to those found in glucose medium. They also showed that in thiosulfate-glutamate medium, the organism used both substrates concomitantly, but they did not report on whether the growth rate, yield, or both were higher in the mixotrophic medium compared to heterotrophic glutamate medium.Our studies, however, revealed a very different picture, and in this paper we present our findings concerning the comparative growth patterns of T. novellus in autotrophic, heterotrophic, and mixotrophic environments. MATERIALS AND METHODSOrganism and growth procedures. The ATCC type strain of T. novellus (no. 8093) was used throughout; the experiment presented in Fig. 2 was also carried out by using our laboratory strain (6), with very similar results. The basal medium employed was similar to that previously described for T. novellus (6) except that FeCl3.6H20 was omitted, and a different trace elements solution (16), which contained a higher amount of iron, was used. There is no agreement on the pH for the cultivation of T. novellus, values ranging between 6.8 and 9.0 having been used (2,6,13,15). Our control experiments, in which the culture pH was maintained constant during growth by means of a pH stat (see below), showed that the...

To investigate the physiological basis of decreased rate of glucose utilization by Thiobacillus novellus in a mixotrophic environment (R. C. Perez and A. Matin, J. Bacteriol. 142:633-638, 1980), its glucose transport system was characterized and the modulation of this system as well as enzymes of glucose metabolism by the growth environment was examined. Uptake of 2-deoxy-D-glucose by cell suspensions was almost abolished by respiratory chain inhibitors, and the sugar accumulated unchanged inside the cells against a concentration gradient: its transport is probably linked to the proton electrochemical gradient. The glucose transport system, as weil as several enzymes of glucose metabolism, had a high specific activity in heterotrophic cells, intermediate activity in mixotrophic cells, and low activity in autotrophic cells; thus, they are induced by glucose but repressed by thiosulfate, its metabolites, or both. Thiosulfate and sulfite inhibited the glucose transport system uncompetitively and noncompetitively, respectively (apparent Ki = 3.1 x 10-2 M and 3.3 x 10-7 M, respectively) and also inhibited

The modern field of biology has its roots in the curiosity and skill of amateur researchers and has never been purely the domain of professionals. Today, professionals and amateurs contribute to biology research, working both together and independently. Well-targeted and holistic investment in amateur biology research could bring a range of benefits that, in addition to positive societal benefits, may help to address the considerable challenges facing our planet in the 21st century. We highlight how recent advances in amateur biology have been facilitated by innovations in digital infrastructure as well as the development of community biology laboratories, launched over the last decade, and we provide recommendations for how individuals can support the integration of amateurs into biology research. The benefits of investment in amateur biology research could be many-fold, however without a clear consideration of equity, efforts to promote amateur biology could exacerbate structural inequalities around access to and benefits from STEM. The future of the field of biology relies on integrating a diversity of perspectives and approaches—amateur biology researchers have an important role to play.