Pre-cold stress increases acid stress resistance and induces amino acid homeostasis in Lactococcus lactis NZ9000

Purpose: To investigate the effects of pre-cold stress treatments on subsequent acid stress resistance and the viability of Lactococcus lactis during acid fermentation.Methods: Bacterial strains were grown at 4 °C for 2 h pre-adaptation, and then subjected to various stresses including exposure to 4 °C, 1 mM hydrogen peroxide, 5 % sodium chloride, 7 % ethanol, and lactic acid (pH 5.5) to determine if any of these stress treatments could increase acid stress resistance and induce amino acid homeostasis during acid fermentation.Results: Among the different abiotic stresses investigated, pre-adaptation of lag-phase cultures to cold shock significantly enhanced cell survival during subsequent acid stress. The stress profile of L. lactis pre-adapted to cold stress revealed induction of amino acid homeostasis and energy balance; however, pre-adaptation responses are induced upon exposure to acid stress alone. Compared to exposure to acid stress only, pre-adaptation to cold stress decreased the redox balance ratio and the formation of hydroxyl radicals, indicating a change in aerobic respiration and oxidative state of the bacteria.Conclusion: Pre-adaptation to cold stress rescued L. lactis from the deleterious effects of subsequent acid exposure by modifying the amino acid metabolic pathway, leading to an improvement in redox mobility of acid stress response.Keywords: Pre-cold stress, Acis stress resistance, Lactococcus lactis, Redox balance, Amino acid homeostasi

Oblikovanje jestivih filmova iz proteina soje unakrsnim vezivanjem transglutaminazom iz bakterije Streptomyces

Soybean protein isolate (SPI) was used in the investigation of the formation of edible protein films through an enzymatic cross-linking method with a purified microbial transglutaminase (MTG) produced from a new effective strain Streptomyces sp. WZFF.L-M1 preserved in our laboratory, followed by the addition of glycerol and suitable heating and drying treatments. Cheaper partially-purified skimmed soybean protein powder (SSP) and whey protein isolates (WPI) were used as the substitutes partially replacing the expensive SPI products, and purified β-lactoglobulin was taken as the positive control of WPI. As a result, the three alternatives could also form highly efficient edible films under the optimal operation conditions. The films made with SPI alternatives, about 50 µm thin, had homogenous network structures, without any holes by direct observation with the naked eye. The tests of the properties of these films showed that they had high water-keeping capacity and strong elasticity, that the ultimate tensile strength (TS) and the elongation at break (Eb) had been remarkably increased (TS>5 MPa, Eb>50 %), and that the prevention rates against the permeability of water vapour and oxygen in the air were also upgraded more than 85 and 70 %, respectively.Izolat proteina soje upotrijebljen je pri oblikovanju jestivih filmova metodom unakrsnog vezivanja transglutaminaze iz novoga soja bakterije Streptomyces sp. WZFF.L-M1, uzgojenog u našem laboratoriju. Nakon dodavanja glicerola, film je zagrijan te osušen. Dio skupih izolata proteina soje zamijenjen je jeftinijim, djelomično pročišćenim obranim prahom proteina soje i izolatima proteina surutke, a pročišćenim β-laktoglobulinom dokazana je prisutnost izolata proteina surutke. Rezultati su pokazali da se u optimalnim uvjetima, upotrebom triju zamjenskih izolata, mogu proizvesti vrlo učinkoviti jestivi filmovi. Struktura filmova debljine oko 50 µm, dobivenih uporabom zamjenskih izolata, bila je homogena, bez okom vidljivih rupica. Rezultati ispitivanja pokazali su veliku moć zadržavanja vode i elastičnost tih filmova. Znatno je povećana granična čvrstoća (>5 MPa) i istezljivost (>50 %) te smanjena njihova propusnost na vodenu paru za 85 % i kisika za 70 %

Oblikovanje jestivih filmova iz proteina soje unakrsnim vezivanjem transglutaminazom iz bakterije Streptomyces

Soybean protein isolate (SPI) was used in the investigation of the formation of edible protein films through an enzymatic cross-linking method with a purified microbial transglutaminase (MTG) produced from a new effective strain Streptomyces sp. WZFF.L-M1 preserved in our laboratory, followed by the addition of glycerol and suitable heating and drying treatments. Cheaper partially-purified skimmed soybean protein powder (SSP) and whey protein isolates (WPI) were used as the substitutes partially replacing the expensive SPI products, and purified β-lactoglobulin was taken as the positive control of WPI. As a result, the three alternatives could also form highly efficient edible films under the optimal operation conditions. The films made with SPI alternatives, about 50 µm thin, had homogenous network structures, without any holes by direct observation with the naked eye. The tests of the properties of these films showed that they had high water-keeping capacity and strong elasticity, that the ultimate tensile strength (TS) and the elongation at break (Eb) had been remarkably increased (TS>5 MPa, Eb>50 %), and that the prevention rates against the permeability of water vapour and oxygen in the air were also upgraded more than 85 and 70 %, respectively.Izolat proteina soje upotrijebljen je pri oblikovanju jestivih filmova metodom unakrsnog vezivanja transglutaminaze iz novoga soja bakterije Streptomyces sp. WZFF.L-M1, uzgojenog u našem laboratoriju. Nakon dodavanja glicerola, film je zagrijan te osušen. Dio skupih izolata proteina soje zamijenjen je jeftinijim, djelomično pročišćenim obranim prahom proteina soje i izolatima proteina surutke, a pročišćenim β-laktoglobulinom dokazana je prisutnost izolata proteina surutke. Rezultati su pokazali da se u optimalnim uvjetima, upotrebom triju zamjenskih izolata, mogu proizvesti vrlo učinkoviti jestivi filmovi. Struktura filmova debljine oko 50 µm, dobivenih uporabom zamjenskih izolata, bila je homogena, bez okom vidljivih rupica. Rezultati ispitivanja pokazali su veliku moć zadržavanja vode i elastičnost tih filmova. Znatno je povećana granična čvrstoća (>5 MPa) i istezljivost (>50 %) te smanjena njihova propusnost na vodenu paru za 85 % i kisika za 70 %

Trace fossil Artichnus pholeoides igen. nov. isp. nov. in Eocene turbidites, Polish Carpathians : possible ascription to holothurians

A hitherto unknown trace fossil was found in some abundance in turbidites of the Polish Outer Carpathians. The occurrence is within the Hieroglyphic Beds of the Silesian Nappe, within the Szczyrzyc Synclinorium, of Middle Eocene age. The trace fossil is a wide, J-shaped structure having a narrow, upward tapering shaft as a connection to the seafloor. The distal end also tapers, to a blind termination. The burrow lumen is surrounded by an irregular spreite structure. The trace fossil is compared with the work of burrowing holothurians, which show some comparative features that suggest a tracemaker belonging to the Apodida

Yeast Extract Promotes Cell Growth and Induces Production of Polyvinyl Alcohol-Degrading Enzymes

Polyvinyl alcohol-degrading enzymes (PVAases) have a great potential in bio-desizing processes for its low environmental impact and low energy consumption. In this study, the effect of yeast extract on PVAases production was investigated. A strategy of four-point yeast extract addition was developed and applied to maximize cell growth and PVAases production. As a result, the maximum dry cell weight achieved was 1.48 g/L and the corresponding PVAases activity was 2.99 U/mL, which are 46.5% and 176.8% higher than the control, respectively. Applying this strategy in a 7 L fermentor increased PVAases activity to 3.41 U/mL. Three amino acids (glycine, serine, and tyrosine) in yeast extract play a central role in the production of PVAases. These results suggest that the new strategy of four-point yeast extract addition could benefit PVAases production

The timing and cause of glacial activity during the last glacial in central Tibet based on Be-10 surface exposure dating east of Mount Jaggang, the Xainza range

Mountain glaciers are sensitive to climate change, and can provide valuable information for inferring former climates on the Tibetan Plateau (TP). The increasing glacial chronologies indicate that the timing of the local Last Glacial Maximum (LGM) recorded across the TP is asynchronous, implying different local influences of the mid-latitude westerlies and Asian Summer Monsoon in triggering glacier advances. However, the well-dated sites are still too few, especially in the transition zone between regions controlled by the two climate systems. Here we present detailed last glacial chronologies for the Mount Jaggang area, in the Xainza range, central Tibet, with forty-three apparent Be-10 exposure-ages ranging from 12.4 +/- 0.8 ka to 61.9 +/- 3.8 ka. These exposure-ages indicate that at least seven glacial episodes occurred during the last glacial cycle east of Mount Jaggang. These include: a local LGM that occurred at similar to 61.9 +/- 3.8 ka, possibly corresponding to Marine Isotope Stage 4 (MIS 4); subsequent glacial advances at similar to 43.2 +/- 2.6 ka and similar to 35.1 +/- 2.1 ka during MIS 3; one glacial re-advance/standstill at MIS3/2 transition (similar to 29.8 +/- 1.8 ka); and three glacial re-advances/standstills that occurred following MIS 3 at similar to 27.9 +/- 1.7 ka, similar to 21.8 +/- 13 ka, and similar to 15.1 +/- 0.9 ka. The timing of these glacial activities is roughly in agreement with North Atlantic millennial-scale climate oscillations (Heinrich events), suggesting the potential correlations between these abrupt climate changes and glacial fluctuations in the Mount Jaggang area. The successively reduced glacial extent might have resulted from an overall decrease in Asian Summer Monsoon intensity over this timeframe. (C) 2018 Elsevier Ltd. All rights reserved

A Rapid, Non-invasive Method for Anatomical Observations of Tadpole Vertebrae in Vivo

The tadpole is a critical stage in the amphibian life cycle and plays an important role during the transition from the aquatic to the terrestrial stage. However, there is a large gap in tadpole research, which represents a vital component of our understanding of the diversity and complexity of the life history traits of amphibians, especially their developmental biology. Some aspects of this gap are due to limited research approaches. To date, X-ray microcomputed tomography (micro-CT) has been widely used to conduct osteology research in adult amphibians and reptiles, but little is known about whether this tool can be applied in tadpole studies. Thus, we compared the results of two methods (the bone-cartilage double-staining technique and micro-CT) to study vertebrae in tadpole specimens. The results revealed no significant difference between the two methods in determining the number of vertebrae, and micro-CT represents a rapid, non-invasive, reliable method of studying tadpole vertebrae. When scanning tadpoles, voltage is the most critical of the scanning parameters (voltage, current and scan time), and moderate scanning parameters are recommended. In addition, micro-CT performed better using specimens stored in 70% ethanol than those preserved in 10% formalin. Finally, we suggest that micro-CT should be more widely applied in herpetological research to increase specimen utilization

Comparative studies on single-layer reduced graphene oxide films obtained by electrochemical reduction and hydrazine vapor reduction

The comparison between two kinds of single-layer reduced graphene oxide (rGO) sheets, obtained by reduction of graphene oxide (GO) with the electrochemical method and hydrazine vapor reduction, referred to as E-rGO and C-rGO, respectively, is systematically studied. Although there is no morphology difference between the E-rGO and C-rGO films adsorbed on solid substrates observed by AFM, the reduction process to obtain the E-rGO and C-rGO films is quite different. In the hydrazine vapor reduction, the nitrogen element is incorporated into the obtained C-rGO film, while no additional element is introduced to the E-rGO film during the electrochemical reduction. Moreover, Raman spectra show that the electrochemical method is more effective than the hydrazine vapor reduction method to reduce the GO films. In addition, E-rGO shows better electrocatalysis towards dopamine than does C-rGO. This study is helpful for researchers to understand these two different reduction methods and choose a suitable one to reduce GO based on their experimental requirements