Enhancement of biomass and fermentation activity of surplus brewers' yeast in a fed-batch process

The growth of surplus brewers' yeast in a fed-batch process was studied with the aim of increasing the fermentation activity of the yeast cells and of optimizing the growth conditions: 20 h cultivation at 30° C and pH 5.0–5.5 using beet molasses as substrate, with a regulated feeding rate, showed satisfactory results. Under the chosen conditions, the final amount of biomass increased more than fivefold, achieving a specific growth rate of 0.1 h^–1 and substrate yield coefficient of 0.54 g·g^–1. The increase in fermentation activity of yeast cells during cultivation correlated very well with the concentration of reduced glutathione, which increased from 1.2 to 2.7 mg·g^–1 (dry matter). At the same time the fermentation activity increased fivefold, which related to the nitrogen content of the yeast cells. Ethanol formation throughout the cultivation did not exceed 0.5 g·l^–1. Correspondence to: B. Strel     

Effects of parathyroid hormone and calcitonin on adenylate cyclase in murine mononuclear phagocytes

Peritoneal mononuclear phagocytes elicited by thioglycollate demonstrate responsiveness to parathyroid hormone (PTH) and calcitonin (CT) which differs from that seen in the normal resident population. PTH causes a twofold stimulation of adenylate cyclase activity in elicited cells but inhibits this activity in resident cells. CT causes a greater stimulation of adenylate cyclase in elicited than in resident cells. Both CT and PTH cause an increase in cyclic AMP accumulation in cultures of elicited mononuclear phagocytes. These results indicate that cells of the mononuclear phagocyte lineage have functional receptors for both PTH and CT. This is the first biochemical evidence to support the hypothesis that mononuclear phagocytes are precursors of the bone resorbing osteoclast.     

Respiratory activity and growth kinetics of Candida yeasts related to carbon sources and available energy

Summary Three yeasts of the genus Candida (Candida intermedia, candida lipolytica and Candida tropicalis) were cultivated batchwise on three different carbon sources: glucose, acetate, and hexadecane. Growth curves, oxygen uptake rates, CO₂ evolution rates and the amount of oxygen required for biomass production were determined. The data were compared and discussed from the point of maximum specific growth rate, maximum oxygen uptake rate, carbon conversion into CO₂ and biomass, consumption of oxygen and available energy for cell synthesis. The results indicated a relationship between _m m, Y_s, Y_O, and for different carbon sources. Y_O and were in the same order of magnitude for acetate (0.58 and 0.38 respectively) and hexadecane (0.45 and 0.40 respectively). These values were remarkably lower than those for glucose (1.26 and 0.54 respectively).Symbols av e^– Available electrons per mol of substrate (dimensionless) - E_av Energy available per mol of substrate (dimensionless) - C_d Dissimilated carbon (%) - m Maximum specific rate of oxygen uptake (mMO₂ h^–1 g^–1) - RQ CO₂ evolved per O₂ consumed - mol. wt. Molecular weight - Y_ATP Biomass mass yield based on mol of ATP generated (g) - Biomass mass yield based on available energy (g) - Y_M Biomass mass yield based on mol of organic substrate (g) - Y_O Biomass mass yield based on oxygen consumed (gg^–1) - 1/Y_O Oxygen consumed for one gram of biomass produced (gg^–1) - Y_s Biomass mass yield based on organic substrate (dimensionless) - b Reductance degree of biomass (equiv. available electrons/g atom carbon) - s Reductance degree of organic substrate (equiv. available electrons/g atom carbon) - Fraction of energy in organic substrate which is converted to biomass - b Weight fraction carbon in biomass (dimensionless) - s Weight fraction carbon in organic substrate (dimensionless) - _m Maximum specific growth rate (h^–1)     

Daily Rhythms Related to Distinct Social Tasks inside an Eusocial Bee Colony

A bee colony is often compared to a multicellular organism, mainly because of its spatial organization. We propose that a temporal organization of equal importance is also present. To support this view, we studied the reproductive processes of two closely related species of stingless bees. Stingless bees enable observations of daily rhythms that are performed by distinct social classes. The emergent process, POP, is cyclic and consists of the building and provisioning of brood cells by the worker bees and egg‐laying by the queen. Colonies were kept in the laboratory under constant conditions with the exit tube opening to the environment; thus, foragers had direct access to environmental cycles. At a later stage of the experiment, the exit tube was closed by a sieve; in this case, bees had their own stock of food, but the environmental LD cycle could still be detected when they were inside the exit tube. Daily POP rhythms were present and showed distinct temporal patterns in each species. A third condition was imposed on one of the species only: the exit tube was closed by a sieve and maintained inside a box that was provided with constant illumination. In this colony, the POP rhythm was perturbed by the destruction of the brood cells. Restoration of POP consisted of a rapid reconstruction of cells followed by a late oviposition in the same day. As different rhythmic patterns were detected, but showed regular timings with respect to one another, an interpretation based upon the concept of an internal temporal order is suggested.     

Synthesis,Antimicrobial Activity and Molecular Docking Study of Novel α‐(Diphenylphosphoryl)‐ and α‐(Diphenylphosphorothioyl)cycloalkanone Oximes

A series of novel α‐(diphenylphosphoryl)‐ and α‐(diphenylphosphorothioyl)cycloalkanone oximes have been synthesized in search for novel bioactive molecules. Their structures were characterized by various spectroscopic methods including IR, NMR (¹H, ³¹P, ¹³C), mass spectrometry and single crystal X‐ray diffraction. The newly synthesized phosphorus‐containing oximes were screened for their in vitro antimicrobial activity against Gram‐positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram‐negative bacteria (Escherichia coli and Salmonella typhimurium) and fungal strains (Candida albicans and Candida glabrata). The biological assays showed that all the studied compounds exhibited high antibacterial and antifungal activities at only 0.1–2.1 μg/mL. In silico molecular docking studies in FabH enzyme active site were performed in order to predict the possible interaction modes and binding energies of the drug candidates at the molecular level.