Valorization of raw glycerol for citric acid production by Yarrowia lipolytica yeast

In the present report, citric acid production from raw glycerol in two fed-batch systems by acetate negative-mutants of Yarrowia lipolytica: Wratislavia 1.31 and Wratislavia AWG7 was compared. In the system, in which the total glycerol concentration was 200 g·L-1, the substrate was added by pulsed additions, and in the other, in which the total glycerol concentration was 300 g·L-1, the substrate was added at a constant feeding rate of 1.4 g·h-1. Despite high citric acid concentrations (155.2 and 157.5 g·L-1 with Y. lipolytica Wratislavia 1.31 and Y. lipolytica Wratislavia AWG7, respectively) obtained from 300 g·L-1 of glycerol, the yield of citric acid was similar, i.e. about 0.6 g·g-1. The volumetric citric acid productivity was markedly higher (1.05 and 0.94 g·L-1h-1 with Y. lipolytica Wratislavia 1.31 and Y. lipolytica Wratislavia AWG7 strains, respectively) in the cultures containing 200 g·L-1 of carbon source

Production of phytases, cellulases and xylanases by selected filamentous fungi

W pracy przebadano dwanaście szczepów grzybów strzępkowych z rodzaju Aspergillus, Trichoderma i Rhizopus pod względem zdolności do biosyntezy fitaz oraz enzymów towarzyszących tj. celulaz i ksylanaz, w hodowlach wstrząsanych oraz SSF, w obecności zmielonej fasoli, skrobi kukurydzianej, rzepaku oraz mąki sojowej jako źródeł węgla. Jedenaście szczepów było zdolnych do biosyntezy fitaz, wykazano jednak znaczne zróżnicowanie poziomu aktywności w zależności od źródła węgla w pożywce. Najefektywniejszym źródłem węgla do syntezy tych enzymów była zmielona fasola oraz skrobia kukurydziana. Największymi uzdolnieniami do biosyntezy fitaz charakteryzowały się szczepy Aspergillus niger 551 (34,56 nKat g⁻¹) oraz Aspergillus cervinus (31,85 nKat g⁻¹). W hodowlach prowadzonych w systemie SSF na zmielonej fasoli z udziałem obu szczepów uzyskano zwiększenie aktywności właściwej fitaz w porównaniu z hodowlą wgłębną. Enzymy towarzyszące, tj. celulazy i ksylanazy, w tych warunkach hodowlanych wytwarzane były na niskim poziomie.Capability of twelve moulds strain represented three different species: Aspergillus, Trichoderma and Rhizopus to biosynthesis of phytase and cellulase and xylanase as society enzymes in shaking cultures and SSF in present of milled been, corn starch, rape-seed and soy-flour, as a carbon source. Eleven strains was able to phytase biosyntesis, by there was a very intensive differences in enzyme activity, common with carbon source in medium. Milled been was the most effective to produce this enzymes, but also corn starch. The highest activity we observed for Aspergillus niger 551 (34,56 nKat·g⁻¹) and Aspergillus cervinus (31,85 nKat·g⁻¹). In SSF cultures on milled been the biosyntesis of phytase was much more effective that previously culture. Society enzymes, such as cellulase and xylanase in proposal media were biosynthesing on very low level

High impact biowastes from South European agro-industries as feedstock for second-generation biorefineries

Availability of bio-based chemicals, materials and energy at reasonable cost will be one of the forthcoming issues for the EU economy. In particular, the development of technologies making use of alternative resources to fossil fuels is encouraged by the current European research and innovation strategy to face the societal challenge of natural resource scarcity, fossil resource dependence and sustainable economic growth. In this respect, second-generation biorefineries, i.e. biorefineries fed with biowastes, appear to be good candidates to substitute and replace the present downstream processing scheme. Contrary to first-generation biorefineries, which make use of dedicated crops or primary cultivations to achieve such a goal, the former employ agricultural, industrial, zootechnical, fishery and forestry biowastes as the main feedstock. This leaves aside any ethical and social issue generated by first-generation approaches, and concomitantly prevents environmental and economical issues associated with the disposal of the aforementioned leftovers. Unfortunately, to date, a comprehensive and updated mapping of the availability and potential use of bioresources for second-generation biorefineries in Europe is missing. This is a lack that severely limits R&D and industrial applications in the sector. On the other hand, attempts at valorizing the most diverse biowastes dates back to the nineteenth century and plenty of information in the literature on their sustainable exploitation is available. However, the large majority of these investigations have been focused on single fractions of biowastes or single steps of biowaste processing, preventing considerations on an integrated and modular (cascade) approach for the whole valorization of organic leftovers. This review aims at addressing these issues by gathering recent data on (a) some of the main high-impact biowastes located in Europe and in particular in its Southern part, and (b) the bio-based chemicals, materials and fuels that can be produced from such residues. In particular, we focused on those key compounds referred to as "chemical platforms", which have been indicated as fundamental to generate the large majority of the industrially relevant goods to date