Characterization and application of recombinant β-glucosidase (BglH) from <Emphasis Type="Italic">Bacillus licheniformis</Emphasis> KCTC 1918

β-Glucosidase (β-1,4-D-glucoside glucohydrolase: EC.3.2.1.21) catalyzes the hydrolysis of β-glucosidic bonds between saccharides and aryl or alkyl groups. A gene encoding β-glucosidase from Bacillus licheniformis KCTC 1918, an anaerobic spore-forming soil bacterium, was cloned and characterized. The structural gene for the β-glucosidase consists of 1410 bp encoding 469 amino acid residues, and has a molecular weight of 53.4 kDa as estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis with 12% separating gel. The enzyme activity was determined against pNPG as a substrate. The enzyme was optimally active at pH 6.0 (citrate-phosphate buffer) and 47°C. β-Glucosidase retained 100% of its original activity for 24 h. The activity of the enzyme was stimulated by glycerol and urea and was decreased by Ca²⁺, Cu²⁺, Hg²⁺, Mg²⁺, and Mn²⁺. In particular, Cu²⁺ had the strongest negative effect on β-glucosidase activity. The purified β-glucosidase was active against pNPG and cellobiose. When the β-glucosidase was tested for cellulose hydrolysis, the supplement of β-glucosidase with cellulose increased the glucose yield from pine wood powder by 139.8%.     

Occurrence and pathogenicity of Phytophthora × cambivora on Prunus laurocerasus in Serbia

Cherry laurel (Prunus laurocerasus) is a native plant species in Serbian forests, but is also widely used for ornamental plantings. Following two extremely wet summers in 2014 and 2015, in spring and summer of 2016 and 2017, numerous cherry laurel plants with symptoms indicative for Phytophthora diseases, like wilting and chlorosis of leaves, dieback and bleeding bark necroses, were recorded in a park in Belgrade and in two ornamental nurseries in central Serbia. From necrotic bark samples and rhizosphere soil, self‐sterile Phytophthora isolates with woolly colonies were obtained. Due to the production of ellipsoid and elongated, non‐papillate sporangia in water and of ornamented oogonia with two‐celled antheridia in mating tests with tester strains of both Phytophthora × cambivora and P. cryptogea, these isolates were identified as P. ×cambivora which was confirmed by ITS sequence analysis. Pathogenicity of P. ×cambivora from cherry laurel (PCCL) was tested by inoculating one‐year‐old seedlings of cherry laurel under the bark. P. ×cambivora from European beech (PCB), and isolates of P. cactorum (CAC), P. cryptogea (CRY), P. plurivora (PLU) and P. ×serendipita (SER) were included as comparison. Three and a half months after inoculation, nine of the twelve plants in PCB, three in PCCL and CAC and two in PLU declined with longitudinal necroses and chlorosis, wilting and premature shedding of leaves. These results demonstrate the ability of P. ×cambivora to infect and cause decline of cherry laurel plants. The particularly high aggressiveness of the P. ×cambivora isolate from beech shows that this pathogen poses a serious risk to cherry laurel in the rare natural communities of cherry laurel and beech in Serbia.     

Prediction of bending properties for structural glulam using optimized distributions of knot characteristics and laminar MOE

This study established a prediction model for bending properties of glued-laminated timber (glulam) using optimized knot and modulus of elasticity (MOE) distributions of lumber laminate as the main input variables. For this purpose, knot and MOE data were investigated for all pieces of lumber that were prepared for glulam manufacturing, and statistical distributions of knot size, knot number in one lumber, and MOE of each laminate were optimized as distribution functions. These knot and MOE data were used as input variables in the prediction model for bending properties, and were also used in generating virtual glulam using the inverse transform method. Prediction of bending properties for glulam was carried out using the transformed section method, which is partially provided in ASTM D 3737 (Annex A4). Predicted values were compared with those from full-scale four-point bending tests for 60 six-layered glulams with 10 different laminar combinations. Finally, the allowable bending properties of glulam for each specific laminate combination were determined by calculating the fifth percentile of the modulus of rupture and the average modulus of elasticity from virtual test results of more than 1000 virtual glulams. From the results of this study, predicted bending properties for glulam and their distributions could be used for structural design in both allowable stress design and limit state design.     

Determination of 2-alkylcyclobutanones with electronic impact and chemical ionization gas chromatography/mass spectrometry (GC/MS) in irradiated foods

The use of a column containing 60 g of silica gel for cleanup and the use of isobutane as a reactant reagent for chemical ionization-mass spectrometric analysis of the saturated and monounsaturated alkyl side-chain 2-alkylcyclobutanones (2-ACBs; specifically induced by irradiation from fat in foods until the proof of contrary) has improved both the sensibility and the selectivity of the method when applied for the detection of irradiated foods. The quality of the chromatograms obtained was improved, allowing the detection of food samples (avocados) irradiated at low doses (0.1 kGy) or irradiated ingredients included in low proportions (less than 5%, wt/wt) in nonirradiated culinary foods. These analytical modifications for the detection of 2-ACBs on the official EN 1785 method enable an extension of its current field of application using common equipment of food quality control laboratories.     

Effects of temperature and agitation rate on the formation of conjugated linoleic acids in soybean oil during hydrogenation process.

The effects of hydrogen temperature and agitation rate on the formation of total conjugated linoleic acids (CLA) and CLA isomers were studied during hydrogenation with a selective Ni catalyst. The CLA isomers were identified by using a 100-m cyano-capillary column gas chromatograph and a silver ion-impregnated HPLC. Reaction temperature and agitation rate greatly affected the quantities of total CLA and individual CLA isomers, and the time to reach the maximum quantity of CLA in the partially hydrogenated soybean oil. As the hydrogenation temperature increased, the maximum quantity of CLA in soybean oil increased, but the time to reach the maximum CLA content decreased. By increasing the hydrogenation temperature from 170 to 210 degrees C, the quantity of CLA obtained was about 2.6 times higher. As the agitation rate decreased, the CLA formation in soybean oil increased, and the time to reach the maximum CLA content also increased. The maximum CLA contents in soybean oil obtained during hydrogenation at 210 degrees C with agitation rates of 300, 500, and 700 rpm were 162.82, 108.62, and 66.15 mg total CLA/g oil, respectively. The present data showed that it is possible to produce high-CLA-content soybean oil without major modification of fatty acid composition by short-time (10 min) selective hydrogenation under high temperature and low agitation rate conditions.     

Drought and ecosystem carbon cycling

Drought as an intermittent disturbance of the water cycle interacts with the carbon cycle differently than the ‘gradual’ climate change. During drought plants respond physiologically and structurally to prevent excessive water loss according to species-specific water use strategies. This has consequences for carbon uptake by photosynthesis and release by total ecosystem respiration. After a drought the disturbances in the reservoirs of moisture, organic matter and nutrients in the soil and carbohydrates in plants lead to longer-term effects in plant carbon cycling, and potentially mortality. Direct and carry-over effects, mortality and consequently species competition in response to drought are strongly related to the survival strategies of species. Here we review the state of the art of the understanding of the relation between soil moisture drought and the interactions with the carbon cycle of the terrestrial ecosystems. We argue that plant strategies must be given an adequate role in global vegetation models if the effects of drought on the carbon cycle are to be described in a way that justifies the interacting processes.     

Modulatory effects of functional rice cultivars giant embryo and Aranghyangchal on the body weight and lipid metabolism in mice fed with a high fat diet

The effects of the functional rice cultivars giant embryo and Aranghyangchal on the body weight and lipid metabolism in male C57BL/6N mice under high fat diet conditions were investigated. The animals were randomly placed into four dietary groups: normal control (NC group), high fat (HF group), and high fat supplemented with giant embryo (HF-GE group) or Aranghyangchal (HF-AR group). After 8weeks, a marked increase in the body weight and plasma triglyceride and total cholesterol concentrations were found in the HF mice relative to the control group. However, the addition of the functional rice samples in the high fat diet reduced the body weight gain and significantly decreased the lipid levels through inhibition of lipogenesis and regulation of adipokine production. The results demonstrate that the functional rice grains giant embryo and Aranghyangchal may both be useful as biomaterials in the development of functional food with therapeutic potential against high fat diet-induced hyperlipidemia.     

Changes in the Functional Components and Radical Scavenging Activity of Korean Maize Hybrids According to Different Cropping Seasons

We evaluated the proximate composition, free sugar content, fatty acid composition, carotenoid content, total phenol content, and radical scavenging activity of the grain from various Korean maize hybrid cultivars grown in two different cropping seasons. The moisture, crude ash, crude fat, crude protein, total starch, and amylose contents were significantly higher in most of the maize hybrid cultivars when grown in the early-season than when grown in the late-season. The free sugar content, fatty acid composition, carotenoid content, and total phenol content differed significantly between cultivars and cropping seasons. The highest unsaturated fatty acid compositions of maize hybrids of early-season and late-season were 86.05 and 86.29%, respectively, in the Daanok cultivar. The carotenoid contents were significantly higher in maize hybrids of late-season compared to those of early-season. The highest total phenol content was 108.09 mg/100 g in Singwangok of the late-season. The radical scavenging activity of maize hybrids differed significantly between cultivars and cropping seasons.     

Comparison of Salt and Drought‐Stress Effects on Maize Growth and Yield Formation with Regard to Acid Invertase Activity in the Kernels

The long‐term effects of salt stress (11 dS m^?1) and drought stress (35 % WHC) were investigated for two maize genotypes, focusing on the relation between metabolic changes around the time of pollination and the impact on yield determinants at maturity. The relatively salt‐resistant hybrid Pioneer 3906 and the relatively drought‐resistant hybrid Fabregas were compared. The experiments were conducted in large plastic containers in a vegetation hall in two consecutive years (2011 and 2012). Plant height and leaf area were significantly reduced under both stress conditions. The transpiration rate was only slightly reduced under drought stress; but under salt stress, a significant reduction occurred 40–53 days after sowing. As a significant increase in sucrose concentrations was observed in the salt‐treated maize kernels 2 days after pollination, the availability of assimilates was not limiting and the plants could afford to save water by reduced stomatal opening. Although under both stress conditions the soluble acid invertase activity was reduced 2 days after pollination, concomitantly, an increase in hexose concentrations was observed. Thus, in these experiments, the delivery of hexoses by acid invertase activity did not limit kernel development. Differences in grain yield at maturity between salt and drought stress were most likely caused by salt‐specific effects (Na⁺ toxicity), Fabregas being more affected than Pioneer 3906.