Isolation and identification of antimicrobial peptides derived by peptic cleavage of whey protein isolate

The antimicrobial potential of whey protein isolate hydrolyzed by gastrointestinal enzymes was determined by attempting to identify and characterize the antimicrobial peptides responsible. While tryptic and chymotryptic hydrolysates did not show antibacterial activity, whey proteins hydrolyzed for 45–90 min by pepsin exhibited significant activity. Fractionation of 60-min hydrolysate by reversed-phase high performance liquid chromatography yielded 5 fractions that were antibacterial, with minimum inhibitory concentrations comprised between 20 and 35 μg/mL. These fractions contained short peptides not previously identified as antimicrobial. Fragment 14–18 (KVAGT) of β-lactoglobulin is very close to a sequence previously identified as antibacterial and is found in antimicrobial sequences of diverse origin. Five other peptides derived from β-lactoglobulin, and one fragment from α-lactalbumin (f117–121, KVGIN), were also identified as antibacterial. The identified peptides do not match pepsin action exactly, indicating modified proteolysis of unknown origin. Protein by-products of the dairy industry offer potential for large-scale production of antimicrobial peptides.     

Relationship of iso‐α‐acid content and endogenous antioxidative potential during storage of lager beer

One of the critical issues regarding the quality of beer is the change in its chemical composition that occurs during storage. Decomposition of iso‐α‐acids results in an undesirable decrease in bitterness as well as a deterioration in the sensory profile of the beer. These changes are caused by the susceptibility of iso‐α‐acids to degradation owing to the influence of reactive oxygen species and light. The aim of this study was to investigate the influence of storage conditions (temperature, light) on the degradation of iso‐α‐acids during aging, with the main focus on monitoring the relationship between the turnover of iso‐α‐acids, the sulphur dioxide content and the antioxidative potential of stored beer as measured by electron spin resonance spectroscopy. In agreement with previous investigations, a significant decrease in the content of bitter compounds (up to 18 % relative to the original level, depending on storage conditions) was observed. A significant decrease in the antioxidant potential of beer was recorded simultaneously and the data confirmed a strong correlation between these parameters. The decline in beer bitterness could become a marker for estimating oxidative damage during storage. Copyright © 2014 The Institute of Brewing & Distilling     

Lactobacillus fermentum BR11, a potential new probiotic, alleviates symptoms of colitis induced by dextran sulfate sodium (DSS) in rats

Current treatments for inflammatory bowel disease (IBD) are relatively ineffective. Recently, probiotics have emerged as a potential treatment modality for numerous gastrointestinal disorders, including IBD. Few probiotics, however, have undergone appropriate preclinical screening in vivo. The current study compared the effects of four candidate probiotics on development of dextran sulfate sodium (DSS)-induced colitis in rats. Sprague Dawley rats were gavaged 1 mL of the potential probiotic (1 x 10(10) CFU/mL), or vehicle, twice daily for 14 days. Strains tested were Lactobacillus rhamnosus GG (LGG), Streptococcus thermophilus TH-4 (TH-4), Bifidobacterium lactis Bb12 (Bb12) and Lactobacillus fermentum BR11 (BR11). Colitis was induced from day 7 to 14 via administration of 2% DSS in drinking water. Disease activity index (DAI) was monitored daily until rats were killed at day 14. DAI decreased in DSS+Bb12 and DSS+BR11 compared to DSS+Vehicle. Colon length increased in DSS+BR11 (10%) and DSS+LGG (10%) compared to DSS+Vehicle. DSS+Bb12 and DSS+BR11 prevented the distal colon crypt hyperplasia evident in DSS+Vehicle, DSS+LGG and DSS+TH-4. BR11 was most effective at reducing colitic symptoms. Bb12 had minimal effects, whilst TH-4 did not prevent DSS-colitis and LGG actually exacerbated some indicators of colitis. Further studies into the potential benefits of L. fermentum BR11 are indicated.     

Multilinear model for spatial pattern analysis of the Measurement of Haze and Visual Effects project

A multilinear model was developed for the analysis of the spatial patterns and possible sources affecting haze and its visual effects in the southwestern United States. The data from the project Measurement of Haze and Visual Effects (MOHAVE) collected during the late winter and mid-summer of 1992 at the monitoring sites in four states (i.e., California, Arizona, Nevada and Utah) were used in the study. The three-way data array was analyzed by a four-product-term model. This study makes a direct effort to include wind patterns as a component in the model in order to obtain the information of the spatial patterns of source contributions. The solution is computed using the conjugate gradient algorithm with applied non-negativity constraints. For the winter data set, reasonable solutions contained six sources and six wind patterns. The analysis of summer data required seven sources and seven wind patterns. The ME results are compared to the prior single-species empirical orthogonal function analysis results--and prior work describing the transport pathways.     

Real-time PCR detection of the thermostable direct hemolysin and thermolabile hemolysin genes in a Vibrio parahaemolyticus cultured from mussels and mussel homogenate associated with a foodborne outbreak

Molecular methods have become vital epidemiological tools in the detection and characterization of bacteria associated with a foodborne outbreak. We used both culture and real-time PCR to detect a Vibrio parahaemolyticus isolate associated with a foodborne outbreak. The outbreak occurred in July 2002 in Polk County, Florida, and originated at a Chinese buffet, with one person being hospitalized. The hospital isolated V. parahaemolyticus from the patient but destroyed the sample after diagnosis. From an onsite visit of the restaurant, food samples that possibly contributed to the outbreak were collected and sent to the Florida Department of Health, Tampa Branch Laboratory. Crab legs, crabsticks, and mussel samples were homogenized and incubated according to the Food and Drug Administration Bacteriological Analytical Manual culture protocol. Three sets of primers and a TaqMan probe were designed to target the tdh, trh, and tlh genes and used for real-time PCR. This study was successful in isolating V. parahaemolyticus from a mussel sample and detecting two of its genes (tdh and tlh) in food and pure culture by real-time PCR.     

碳水化合物——蛋白质饮料对运动耐力的影响

人在长时间运动后的疲劳和体内存储的肌糖原的消耗密切相关,因此运动后糖原合成的速度是短时间内运动恢复的关键因素。接下来的实验有效地研究了运动后补充的营养成分对于再次运动时耐力表现的影响。