Determination of volatile compounds in different hop varieties by headspace-trap GC/MS--in comparison with conventional hop essential oil analysis

A headspace (HS)-trap method in combination with gas chromatography (GC)-mass spectrometry (MS) was developed for the determination of volatile constituents in hops. The highly sensitive HS-trap system reduces the detection limit by using up to four trap enrichment cycles. Seventy hop samples of different varieties and cultivation regions, from the 2008 harvest, were examined using the HS-trap-GC-MS method and the established "European Brewery Convention" (EBC) method for hop essential oil analysis. Twenty-one different volatiles were quantified for each hop sample. For all compounds, except caryophyllene oxide, a strong correlation was found between the results of the HS-trap method and the EBC method. Experiments have revealed that the EBC method using steam distillation is not appropriate for thermolabile compounds, such as caryophyllene oxide, due to decomposition during boiling. The HS-trap method is fast and sensitive, requires small sample amounts and minimal sample preparation, and is easy to apply.     

The Ashbya gossypii genome as a tool for mapping the ancient Saccharomyces cerevisiae genome

We have sequenced and annotated the genome of the filamentous ascomycete Ashbya gossypii. With a size of only 9.2 megabases, encoding 4718 protein-coding genes, it is the smallest genome of a free-living eukaryote yet characterized. More than 90% of A. gossypii genes show both homology and a particular pattern of synteny with Saccharomyces cerevisiae. Analysis of this pattern revealed 300 inversions and translocations that have occurred since divergence of these two species. It also provided compelling evidence that the evolution of S. cerevisiae included a whole genome duplication or fusion of two related species and showed, through inferred ancient gene orders, which of the duplicated genes lost one copy and which retained both copies.     

Antimicrobial ability and growth promoting effects of feed supplemented with probiotic bacterium isolated from gut microflora of Cirrhinus mrigala

The present studies were conducted to isolate, select, identify and characterize gut bacteria as antimicrobial and growth promoting agent for the feed of economically important fish Cirrhinus mrigala. Intestinal microflora were isolated, counted, and identified, and their in vitro antibacterial properties were determined. The results have revealed that occurrence of Gram-negative rods was around 75% and of Gram-positive rods was 25%. Among the isolates Gram-positive were maintained in nutrient agar slants at 4°C. Of these, eight strains were replica-plated on agar seeded with Aeromonas hydrophila and only one strain CM2(C. mrigala 2) exhibited antibacterial properties in vitro showing inhibition against fish pathogen by well diffusion assay. This isolated strain was identified as Bacillus cereus. This bacterium was mass cultured and incorporated in the pelleted diet(40% protein and 18 k J g–1 gross energy) of C. mrigala to investigate its effect on growth performance, digestibility, nutrient retention and activities of digestive enzymes. The results of feeding trial revealed significantly(P<0.05) high growth performance in terms of specific growth rate, growth percent gain in body weight(BD)(272.4±1.5)%, high apparent protein digestibility((79.9±0.30)%) and low food conversion ratio in the group of fishes fed on diet containing B. cereus in comparison to the fishes fed on diet without probiotics. The carcass composition also revealed high accumulation of proteins((15.28±0.15) g 100 g–1) in fishes fed on diet containing probiotics. Intestinal enzyme activities of protease, amylase and cellulase were also significantly(P<0.05) high in the group of fishes fed on diet supplemented with probiotics indicating the extracellular enzyme production by B. cereus. These results indicate that probiotics stimulate the digestion through the supply of digestive enzyme and certain essential nutrients to animals. Also significantly(P<0.05) low excretion of metabolites, i.e., ammonia excretion and phosphate production(mg kg–1 BW d–1) was observed in the fishes fed with probiotic based diets. Thus, B. cereus appears to be a promising candidate for ptobiotic applications which can enhance growth performance and nutrient retention in C. mrigala.     

Digestibility of proteins and starch (in vitro) of amphidiploids (black gram×mung bean) as affected by domestic processing and cooking

The effects of different domestic processing and cooking methods on starch digestibility (in vitro) and protein digestibility (in vitro) of four strains of amphidiploids (black gram×mung bean) were investigated. An increase of 35 to 48% and 22 to 25% was observed in starch digestibility and protein digestibility, respectively, when the seed of amphidiploids were soaked for 18 h. Cooking (both of unsoaked and soaked seeds) and germination improved significantly the starch digestibility and protein digestibility of all the varieties.     

Survival of south african strains of biovar 2 and biovar 3 ofPseudomonas solanacearum in the roots and stems of weeds

Summary South African strains of biovar 2 and biovar 3 ofPseudomonas solanacearum were compared for their ability to survive in the roots and stems of ten weed species. After artificial inoculation with a biovar 2 strain none of the weed species developed wilt symptoms, but the pathogen was isolated from one species,Physalis angulata L. Using inoculum of a biovar 3 strain, two of the weed species developed wilt symptoms (Datura stramonium L.,Solanum nigrum L.), and the pathogen was isolated from four species,Eragrostis curvula, Amaranthus hybridus L.,Datura stramonium L. andSolanum nigrum.     

Failure to respond to endogenous or exogenous melatonin may cause nonphotoresponsiveness in Harlan Sprague Dawley rats

Background  

Responsiveness to changing photoperiods from summer to winter seasons is an important but variable physiological trait in most temperate-zone mammals. Variation may be due to disorders of melatonin secretion or excretion, or to differences in physiological responses to similar patterns of melatonin secretion and excretion. One potential cause of nonphotoresponsiveness is a failure to secrete or metabolize melatonin in a pattern that reflects photoperiod length.     

Comparative study of the culturable microbiota present in two different rearing systems,flow‐through system (FTS) and recirculation system (RAS), in a great scallop hatchery

A comparison of the culturable microbiota present in the different compartments of a great scallop (Pecten maximus) hatchery with two experimental production systems, FTS and RAS, throughout a cycle of larval rearing was carried out. All isolates obtained from broodstock gonads, larvae, tank water, biofilm, microalgae, UV‐treated water and biofilter in both systems at three sampling times were characterized by biochemical tests and identified by sequencing of the 16S rRNA gene. Some of the genera were found to be exclusive of broodstock gonads, such as Sinobacterium, Kordia or Microbulbifer, and differences between gonad microbiota before and after spawning were detected. The number of morphotypes obtained in water, larvae and biofilm was similar in both systems, as well as the behaviour of the microbial populations in almost all hatchery compartments, in which Vibrio, Neptuniibacter, Pseudoalteromonas and Shewanella were the most common genera. The diversity obtained was analysed using the principal component analysis (PCA) and Fisher's exact test, showing that the microbial communities present in the common compartments between FTS and RAS did not significantly differ. These results suggest that, at least from a microbiological point of view, the recirculation system could be a good alternative for the production of scallop larvae.