Procjena uzgoja Aspergillus niger u geometrijski različitim bioreaktorima na osnovi morfoloških analiza

The growth of Aspergillus niger, citric acid production and mycelia morphology changes were compared under different mixing conditions in bioreactors with two types of stirrers: Rushton turbine stirrers (RTS1 or RTS2) and axial counterflow stirrers (ACS1 or ACS2). The characteristics of growth, productivity and morphology varied with the mixing system and the applied agitation regime. In the first series of experiments, the flow characteristics of Aspergillus niger broth under different mixing conditions were analysed in a model bioreactor using RTS1 and ACS1. The kinetic energy E of flow fluctuations was measured in gassed and ungassed water and fermentation broth systems using a stirring intensity measuring device (SIMD-f1). The difference of energy E values at different points was more pronounced in the bioreactor with RTS1 than in the case of ACS1. High viscous A. niger broths provided higher energy E values in comparison with water. It was observed that the Aspergillus niger growth rate and citric acid synthesis rate decreased at very high energy E values, the behaviour obviously being connected with the influence of the irreversible shear stress on the mycelial morphology. In the second series of experiments, a higher citric acid yield was achieved in the case of ACS2 at a power input approximately twice lower than in the case of RTS2. Morphological characterization of A. niger pellets was carried out by the image analysis method. ACS2 provided the development of morphology, where pellets and cores had larger area, perimeter and diameter, and the annular region of pellets was looser and more »hairy« in comparison with the case of RTS2. The pellets from the fermentation with RTS2 were smaller, denser, with shorter hyphae in the annular region of pellets, and the broth was characterized by a higher percentage of diffuse mycelia. Power input studies of RTS2 and ACS2 were made at different agitator rotation speeds and gas flow rates using water and Aspergillus niger broths. RTS2 was a high power number mixing system (PO = 6.8), whose PO was practically invariable in different media under study. For ACS2, PO increased approximately 3 times from 0.68 in water to 2.11 in high viscous Aspergillus niger broth. The effect of the agitation and aeration rates on the power input of RTS2 and ACS2 was analysed. ACS2 proved to be more effective, since it lost much less power due to aeration.Ispitivani su rast Aspergillus niger, proizvodnja limunske kiseline i promjene u morfologiji micelija pod različitim uvjetima miješanja u bioreaktorima s dva tipa miješalica: Rushton turbinske miješalice (RTS1 ili RTS2) i aksijalno protustrujne miješalice (ACS1 i ACS2). Značajke rasta, proizvodnosti i morfologija mijenjali su se s vrstom miješalica i načinom miješanja. U prvoj seriji pokusa analizirane su značajke protoka komine s A. niger pod različitim uvjetima miješanja u modelnom bioreaktoru s miješalicama RTS1 i ACS1. Kinetička energija E fluktuacije protoka mjerena je u vodi s aeracijom i bez nje, te u fermentacijskim kominama koristeći uređaj za mjerenje intenziteta miješanja (SIMD-f1). Razlika u količini energije E na različitim mjestima u bioreaktoru bila je izrazitija u bioreaktoru s RTS1 nego s ACS1. Jako viskozna A. niger komina zahtijevala je veće vrijednosti E u usporedbi s vodom. Opaženo je da brzina rasta A. niger i sinteza limunske kiseline opadaju pri visokim vrijednostima energije E, što je očito povezano s utjecajem ireverzibilnog naprezanja na posmik na morfologiju micelija. U drugoj seriji pokusa postignuti su veliki prinosi limunske kiseline primjenom ACS2, pri približno dvostruko manjem utrošku energije u usporedbi s primjenom RTS2. Morfološka karakterizacija peleta A. niger provedena je postupkom analize fotografija. Primjenom ACS2 peleti i jezgre bili su veći po opsegu i promjeru, a anularno područje peleta bilo je labavije i »dlakavije« u usporedbi s pokusima s RTS2. Peleti od fermentacije s RTS2 bili su manji, gušći, s kraćim hifama u anularnom području peleta, a komina je sadržavala veći postotak difuznih micelija. Studije utroška snage primjenom RTS2 i ACS2 provedene su pri različitim brzinama okretaja miješalica i protoka zraka u vodi i u komini s A. niger. RTS2 ima sustav miješanja s velikim utroškom snage (P0 = 6,8) koji se praktički ne mijenja ako se promijeni medij. Za ACS2 se P0 povećava približno tri puta, od 0,68 u vodi do 2,11 u viskoznoj komini s A. niger. Analiziran je utjecaj miješanja i jačine aeracije na utrošak energije primjenom RTS2 i ACS2. ACS2 bio je djelotvorniji jer se aeracijom gubilo puno manje energije

Performance of Aspergillus niger Cultivation in Geometrically Dissimilar Bioreactors Evaluated on the Basis of Morphological Analyses

The growth of Aspergillus niger, citric acid production and mycelia morphology changes were compared under different mixing conditions in bioreactors with two types of stirrers: Rushton turbine stirrers (RTS1 or RTS2) and axial counterflow stirrers (ACS1 or ACS2). The characteristics of growth, productivity and morphology varied with the mixing system and the applied agitation regime. In the first series of experiments, the flow characteristics of Aspergillus niger broth under different mixing conditions were analysed in a model bioreactor using RTS1 and ACS1. The kinetic energy E of flow fluctuations was measured in gassed and ungassed water and fermentation broth systems using a stirring intensity measuring device (SIMD-f1). The difference of energy E values at different points was more pronounced in the bioreactor with RTS1 than in the case of ACS1. High viscous A. niger broths provided higher energy E values in comparison with water. It was observed that the Aspergillus niger growth rate and citric acid synthesis rate decreased at very high energy E values, the behaviour obviously being connected with the influence of the irreversible shear stress on the mycelial morphology. In the second series of experiments, a higher citric acid yield was achieved in the case of ACS2 at a power input approximately twice lower than in the case of RTS2. Morphological characterization of A. niger pellets was carried out by the image analysis method. ACS2 provided the development of morphology, where pellets and cores had larger area, perimeter and diameter, and the annular region of pellets was looser and more »hairy« in comparison with the case of RTS2. The pellets from the fermentation with RTS2 were smaller, denser, with shorter hyphae in the annular region of pellets, and the broth was characterized by a higher percentage of diffuse mycelia. Power input studies of RTS2 and ACS2 were made at different agitator rotation speeds and gas flow rates using water and Aspergillus niger broths. RTS2 was a high power number mixing system (PO = 6.8), whose PO was practically invariable in different media under study. For ACS2, PO increased approximately 3 times from 0.68 in water to 2.11 in high viscous Aspergillus niger broth. The effect of the agitation and aeration rates on the power input of RTS2 and ACS2 was analysed. ACS2 proved to be more effective, since it lost much less power due to aeration

The COP9/signalosome complex is conserved in fission yeast and has a role in S phase

The COP9/signalosome complex is conserved from plant to mammalian cells. In Arabidopsis, it regulates the nuclear abundance of COP1, a transcriptional repressor of photomorphogenic development [1] [2]. All COP (constitutive photomorphogenesis) mutants inappropriately express genes that are normally repressed in the dark. Eight subunits (Sgn1-Sgn8) of the homologous mammalian complex have been purified [3] [4]. Several of these have been previously identified through genetic or protein interaction screens. No coherent model for COP9/signalosome function has yet emerged, but a relationship with cell-cycle progression by transcriptional regulation, protein localisation or protein stability is possible. Interestingly, the COP9/signalosome subunits possess domain homology to subunits of the proteasome regulatory lid complex [5] [6]. Database searches indicate that only Sgn5/JAB1 is present in Saccharomyces cerevisiae, precluding genetic analysis of the complex in cell-cycle regulation. Here we identify a subunit of the signalosome in the fission yeast Schizosaccharomyces pombe through an analysis of the DNA-integrity checkpoint. We provide evidence for the conservation of the COP9/signalosome complex in fission yeast and demonstrate that it functions during S-phase progression

Search for new physics in dijet angular distributions using proton-proton collisions at root s=13 TeV and constraints on dark matter and other models

An Erratum to this article was published on 29 April 2022: https://doi.org/10.1140/epjc/s10052-022-10278-0search is presented for physics beyond the standard model, based on measurements of dijet angular distributions in proton-proton collisions at root s = 13 TeV. The data collected with the CMS detector at the LHC correspond to an integrated luminosity of 35.9 fb(-1). The observed distributions, corrected to particle level, are found to be in agreement with predictions from perturbative quantum chromodynamics that include electroweak corrections. Constraints are placed on models containing quark contact interactions, extra spatial dimensions, quantum black holes, or dark matter, using the detector-level distributions. In a benchmark model where only left-handed quarks participate, contact interactions are excluded at the 95% confidence level up to a scale of 12.8 or 17.5 TeV, for destructive or constructive interference, respectively. The most stringent lower limits to date are set on the ultraviolet cutoff in the Arkani-Hamed-Dimopoulos-Dvali model of extra dimensions. In the Giudice-Rattazzi-Wells convention, the cutoff scale is excluded up to 10.1 TeV. The production of quantum black holes is excluded for masses below 5.9 and 8.2 TeV, depending on the model. For the first time, lower limits between 2.0 and 4.6 TeV are set on the mass of a dark matter mediator for (axial-)vector mediators, for the universal quark coupling g(q) = 1.0.Peer reviewe