Enzymatic lysis of yeast cell walls

Lysis of yeast cell walls using zymolase and lysozyme was studied. During coupled zymolase–lysozyme treatment, nearly three times more reducing sugars were released from the yeast cells compared to controls. Enzyme treatment followed by extraction at pH 9 resulted in a yield of more than 80% of the total nitrogen of the yeast cell. Protein degradation occurred during enzyme treatment. The precipitation of proteins was significantly increased by succinylation after enzyme treatment. This also reduced the nucleic acid content of the yeast proteins to less than 2% and enhanced the extractability of nitrogenous material.     

Catabolism of benzoate and monohydroxylated benzoates by Amycolatopsis and Streptomyces spp

Eight actinomycetes of the genera Amycolatopsis and Streptomyces were tested for the degradation of aromatic compounds by growth in a liquid medium containing benzoate, monohydroxylated benzoates, or quinate as the principal carbon source. Benzoate was converted to catechol. The key intermediate in the degradation of salicylate was either catechol or gentisate, while m-hydroxybenzoate was metabolized via gentisate or protocatechuate. p-Hydroxybenzoate and quinate were converted to protocatechuate. Catechol, gentisate, and protocatechuate were cleaved by catechol 1,2-dioxygenase, gentisate 1,2-dioxygenase, and protocatechuate 3,4-dioxygenase, respectively. The requirement for glutathione in the gentisate pathway was dependent on the substrate and the particular strain. The conversion of p-hydroxybenzoate to protocatechuate by p-hydroxybenzoate hydroxylase was gratuitously induced by all substrates that were metabolized via protocatechuate as an intermediate, while protocatechuate 3,4-dioxygenase was gratuitously induced by benzoate and salicylate in two Amycolatopsis strains.     

Characterization and chromosome localization of a processed pseudogene related to the bovine laminin receptor gene family

A bovine BAC clone containing a processed laminin receptor pseudogene (LAMR1P) has been isolated and characterized. A 2,901-bp sequence was produced from the clone, of which 1,187 bp represented seven identifiable exon-like domains, but no intervening sequences. The pseudogene sequence reveals several transversions and transitions, as well as insertions and deletions. A premature stop codon motif is present at nucleotide position 115 located in the exon-2-like domain. Physical mapping of the gene was performed by FISH and RH panel mapping and assigned LAMR1P to BTA4q24-->q26 with the closest linkage to BM6458 (19 cR, LOD score of 11.6). The functional laminin receptor putatively plays an important role in the transmission of bovine spongiform encephalopathy (BSE). In this process, the receptor supposedly acts as the binding site for prion proteins to enter mammalian cells. Considering the existence of several human laminin receptor pseudogenes forming a complex family, any knowledge of even pseudogene sequences might be helpful to isolate the functional bovine laminin receptor gene.     

Associations of GH gene variants with performance traits in F2 generations of European wild boar, Piétrain and Meishan pigs

The role of the porcine GH gene was investigated in 292 F₂ animals of mating Wild Boar × Piétrain and in 310 F₂ animals of mating Meishan × Piétrain. Forty-three traits of fattening, carcass composition, meat quality and stress resistance were recorded. For the analysis of associations between GH gene variants and quantitative traits, two restriction fragment length polymorphisms were examined. In the Meishan × Piétrain family eight traits related to fatness were significantly associated with GH genotypes, while in the Wild Boar × Piétrain family no significant associations were found. In the Meishan × Piétrain cross, the GH locus explained 11·7% to 17·7% of the total phenotypic variance in the F₂ population. The possibility of multiple alleles at the GH locus is discussed. Based on these results, we conclude that the GH locus should be further investigated in commercial breeds to determine its suitability for use in marker-assisted selection programmes.     

Metastable states of water and ice during pressure-supported freezing of potato tissue

Different ice modifications were obtained during freezing processes at several pressure levels from atmospheric pressure up to 300 MPa. In the pressure range between 210 and 240 MPa, a metastable ice I modification area was observed, as the nucleation of ice I crystals in the thermodynamically stable region of ice III was reached. A significant degree of supercooling was obtained before freezing the tissue water to ice III, which has to be considered when designing pressure-supported freezing processes. The effect of supercooling phenomenon on the phase transition time is discussed using a mathematical model based on the solution of the heat transfer governing differential equations. Phase transition and freezing times for the different freezing paths experimented are compared for the processes: freezing at atmospheric pressure, pressure-assisted freezing, and pressure-shift freezing. Different metastable states of liquid water are defined according to their process-dependent stability.     

Exudation: an expanding technique for continuous production and release of secondary metabolites from plant cell suspension and hairy root cultures

This review addresses methods of obtaining secondary metabolites from plant cell suspension and hairy root cultures and their exudates, particularly the physiological mechanisms of secondary metabolites release and trafficking. The efficiency for product recovery of metabolites can be increased by various methods, based on the principle of continuous product release into the cultivation medium. The most common methods for metabolite recovery are elicitation, influencing membrane permeability, and in situ product removal. The biosynthetic pathways can be influenced by cultivation conditions, transformation, or application of elicitors. The membrane permeability can be altered through the application of chemical or physical treatments. Product removal can be greatly increased through a two-phase system and the introduction of absorbents into the cultivation medium. In this review, we describe some improved approaches that have proven useful in these efforts.     

Biogas digestate as a sustainable phytosterol source for biotechnological cascade valorization

Every year, several million tonnes of anaerobic digestate are produced worldwide as a by-product of the biogas industry, most of which is applied as agricultural fertilizer. However, in the context of a circular bioeconomy, more sustainable uses of residual digestate biomass would be desirable. This study investigates the fate of the sterol lipids β-sitosterol and cholesterol from the feedstocks to the final digestates of three agricultural and one biowaste biogas plants to assess if sterols are degraded during anaerobic digestion or if they remain in the digestate, which could provide a novel opportunity for digestate cascade valorization. Gas chromatographic analyses showed that feedstock sterols were not degraded during anaerobic digestion, resulting in their accumulation in the digestates to up to 0.15% of the dry weight. The highest concentrations of around 1440 mg β-sitosterol and 185 mg cholesterol per kg dry weight were found in liquid digestate fractions, suggesting partial sterol solubilization. Methanogenic batch cultures spiked with β-sitosterol, cholesterol, testosterone and β-oestradiol confirmed that steroids persist during anaerobic digestion. Mycobacterium neoaurum was able to transform digestate sterols quantitatively into androstadienedione, a platform chemical for steroid hormones, without prior sterol extraction or purification. These results suggest that digestate from agricultural and municipal biowaste is an untapped resource for natural sterols for biotechnological applications, providing a new strategy for digestate cascade valorization beyond land application.