Search

The possibility of using a composite material based on bovine serum albumin (BSA) covalently bonded with ferrocenecarboxaldehyde and containing carbon nanotubes (CNT) for the immobilization of Blastobotrys adeninivorans BKM Y-2677 (B. adeninivorans) yeast is discussed. The optimal ratio of ferrocenecarboxaldehyde to BSA for the redox-active polymer synthesis is 1:2, since the heterogeneous electron transfer constant is 0.45 ± 0.01 s−1. When carbon nanotubes (CNTs) are added to this polymer, the heterogeneous electron transfer constant increases: at a CNT specific density of 2.5 µg/mm2, it reaches a maximum value of 0.55 ± 0.01 s−1. The addition of CNTs into the conducting system leads to increasing of the rate constant of interaction redox species with B. adeninivorans yeast by an order: the rate constant of interaction between B. adeninivorans yeast and electroactive particles in a redox-active polymer is 0.056 ± 0.005 dm3/g × s and in a composite material based on CNTs is 0.51 ± 0.02 dm3/g × s. The yeast specific density at the electrode of 0.1 mg/mm2 and electrolyte pH of 6.2 was chosen as the working value for the receptor system operation. Immobilized in a composite material, yeast oxidizes a wider range of substrates compared with a similar receptor element based on the ferrocene mediator. The biosensors formed on the basis of hybrid polymers have a high sensitivity with a lower limit of determined concentrations of 1.5 mg/dm3 with an assay time of 5 min and a high correlation (R = 0.9945) with the results of the standard method for determining biochemical oxygen demand (BOD) in nine real surface water samples of the Tula region. [ABSTRACT FROM AUTHOR]

Yeasts are gaining increasing attention as alternative protein sources in fish feeds. The nutritional value of yeast depends on cultivation conditions, yeast species and processing conditions used after harvesting. The objective of the current study was to evaluate the effect of autolysis on apparent digestibility coefficients (ADCs) of crude protein and amino acids (AA) of different yeasts species in Atlantic salmon (Salmo salar). Three yeast species (i.e. Cyberlindnera jadinii , Blastobotrys adeninivorans and Wickerhamomyces anomalus) produced from hydrolysates of pre-treated wood and chicken products were used. After harvesting, each yeast was either directly heat-inactivated with spray-drying or autolyzed at 50 °C for 16 h followed by spray-drying. The treatments consisted of a high-quality fishmeal-based reference diet and six test diets containing 30% of each of the yeast product and 70% of the reference diet. The results showed that protein and AA digestibility differed among the yeast species and that the effect of autolysis on nutrient digestibility was inconsistent among the three yeast species. The ADCs of protein in inactivated yeasts were 63%, 72%, 66% in C. jadinii, B. adeninivorans and W. anomalus , respectively. Autolysis increased the ADCs of protein by 12% and 9% in C. jadinii and W. anomalus , respectively, while it remained unchanged for B. adeninivorans. The ADCs of lysine were 67%, 79% and 72% in inactivated C. jadinii, B. adeninivorans and W. anomalus , respectively. Autolysis improved the ADCs of lysine by 15%, 7% and 13% in C. jadinii, B. adeninivorans and W. anomalus , respectively. The ADCs of methionine in inactivated yeasts was 47% in C. jadinii , 81% in B. adeninivorans and 74% in W. anomalus. After autolysing the yeasts, the ADC of methionine improved by 26% and 4% in C. jadinii and B. adeninivorans, respectively, while it slightly reduced by 2% in W. anomalus. Data from regression analyses showed that digesta viscosity, digesta dry matter and nitrogen solubility are important determinants of protein digestibility of yeasts in fish. In addition, cell wall porosity as demonstrated by nitrogen solubility test, had a larger impact on nutrient digestibility of yeasts compared to the cell wall thickness. In conclusion, the digestibility of protein and AA of yeasts in Atlantic salmon depends on type of yeasts and down-stream processing applied after harvesting. Also, the particular in vitro digestibility method used in the current study did not adequately reflect the protein digestibility of yeasts in Atlantic salmon. • ADCs of sum AA were 57%, 73% and 68% in C. jadinii , B. adeninivorans and W. anomalus , respectively. • Autolysis increased ADCs of sum amino acids in the three yeasts. • Digestibility was low for cysteine (25–47%) and low to moderate for methionine (47–81%) in the three yeast. • Nutrient digestibility of yeasts depends on the type of yeasts and processing used after harvesting. [ABSTRACT FROM AUTHOR]

Blastobotrys adeninivorans plays an essential role in pile-fermenting of Pu-erh tea. Its ability to assimilate various carbon and nitrogen sources makes it available for application in a wide range of industry sectors. The genome of B. adeninivorans TMCC 70007 isolated from pile-fermented Pu-erh tea was sequenced and assembled. Proteomics analysis indicated that 4900 proteins in TMCC 70007 were expressed under various culture conditions. Proteogenomics mapping revealed 48 previously unknown genes and corrected 118 gene models predicted by GeneMark-ES. Ortho-proteogenomics analysis identified 17 previously unidentified genes in B. adeninivorans LS3, the first strain with a sequenced genome among the genus Blastobotrys as well. More importantly, five species specific genes were identified from TMCC 70007, which could serve as a barcode for strain typing and were applicable for fermentation process protection of this industrial species. The datasets generated from tea aqueous extract culture not only increased the proteome coverage and accuracy but also contributed to the identification of proteins related to polyphenols and caffeine, which were considered to change greatly during the microbial fermentation of Pu-erh tea. This study provides a proteome perspective on TMCC 70007, which was considered to be an important strain in the production of Pu-erh tea. The systematic proteogenomics analysis not only made a better annotation on the genome of B. adeninivorans TMCC 70007 as previous proteogenomics study but also provided solution for fermentation process protection on valuable industrial species with species specific genes uniquely identified from proteogenomics study.

Converting cassava stem (CS) to bioethanol instead of burning or allowing them to decay on open fields can contribute to efforts on reducing CO2 emission and fossil fuel use. New xylose‐glucose fermenting yeast Blastobotrys adeninivorans XE1 was inoculated on non‐detoxified acid hydrolysate of CS to produce ethanol. Experimentally, at low furfural concentrations (0.24 ± 0.05 g/L) in non‐detoxified acid hydrolysate of 100 g CS/L, B adeninivorans XE1 (~107 CFU/mL initial concentration) degraded furfural fast and then converted both glucose and xylose to ethanol. However, at higher furfural concentration (0.51 ± 0.11 g/L) in non‐detoxified acid hydrolysate of 150 g CS/L, B adeninivorans XE1 (around 107 CFU/mL) was unable to degrade all furfural, ethanol production by B adeninivorans XE1 was reduced. Increasing initial concentration of B adeninivorans XE1 to around 108 CFU/mL surpassed furfural inhibition and produced 17.4 ± 0.8 g/L ethanol on medium of non‐detoxified acid hydrolysate of 150 g CS/L after 60 hr. [ABSTRACT FROM AUTHOR]