Safety assessment of Lactobacillus strains: presence of putative risk factors in faecal, blood and probiotic isolates

The widespread use of immunosuppressive therapy and antimicrobial agents as well as novel probiotics without a long history of safe use has increased requirements for safety assessment of probiotic lactobacilli. In this study 44 faecal, 52 blood and 15 probiotic isolates (including 3 dairy strains) of Lactobacillus were assayed for their adhesion properties to extracellular matrix proteins and mucus, hemolysis, ability to avoid the induction of respiratory burst in peripheral blood mononucleocytes (PMN) and resistance to human serum. Among tested strains adhesion to collagen, fibrinogen and mucus was isolate-specific and no statistically significant differences were obtained between faecal, blood and probiotic isolates. However, blood isolates showed a trend for higher adhesion to mucus than probiotic strains (P=0.07). Probiotic strains induced lower respiratory burst in PMN when compared to the blood isolates (P<0.05). Moreover, there was a positive correlation between adhesion to collagen and induction of respiratory burst for faecal isolates (P<0.05). In the determination of serum resistance, probiotic strains showed a trend for lower sensitivity to human serum-mediated killing when compared to the faecal isolates (P=0.07). None of the measurable virulence factors were found to be present at statistically higher level in clinical blood isolates when compared to faecal and/or probiotic isolates indicating that these factors do not cause risk when safety of probiotics is considered. However, the significance of adhesion to mucus, low induction of respiratory burst in PMN and resistance to human serum-mediated killing may need further evaluation in experimental animal models and in epidemiological data.     

Specific Bifidobacterium strains isolated from elderly subjects inhibit growth of Staphylococcus aureus

Cell-free, pH-controlled supernatants of thirty-eight Bifidobacterium strains isolated from healthy elderly subjects were subjected to antimicrobial activity assay. Bioluminescent indicator strains Staphylococcus aureus RN4220, Escherichia coli K-12, and Salmonella enterica serovar Typhimurium ATCC 14028 were used as targets of antimicrobial activity. The effect of nutrient depletion on the inhibition was eliminated with spent-culture controls. Three out of thirty-eight Bifidobacterium strains were capable of inhibiting the growth of S. aureus. The inhibition was equal to 23.2+/-19.1% to 50.4+/-26.7% of the inhibition caused by 50 IU/ml nisin. Reuterin-producing positive strain Lactobacillus reuteri SD2112 was capable of 86.0+/-24.6% inhibition, but Bifidobacterium lactis Bb-12, a known probiotic strain, showed no inhibition. None of the strains was capable of inhibiting the growth of E. coli or S. enterica. The observed inhibition by bifidobacteria was related to hydrogen peroxide formation and possible production of heat-stable proteinaceous compounds. The results suggest that production of antimicrobial substances other than organic acids is not common among Bifidobacterium strains typical of elderly subjects. However, specific strains were identified which showed considerable inhibitory activity against S. aureus.     

The effect of dietary forage to concentrate ratio and forage type on milk fatty acid composition and milk fat globule size of lactating cows

We examined the effects of 2 grass silage-based diets differing in forage:concentrate (FC) ratio and those of a red clover silage-based diet on intake, milk production, ruminal fatty acid (FA) biohydrogenation, milk FA composition, and milk fat globule (MFG) size distribution. Ten multiparous Nordic Red cows received the following treatments: grass silage-based diets containing high (70:30, HG) or low (30:70, LG) FC ratio or a red clover silage-based diet with an FC ratio of 50:50 (RC) on a dry matter basis. Determinations of MFG were performed from fresh milk samples without addition of EDTA so the results of fat globules >1 µm in diameter are emphasized instead of the entire globule population. Lower FC ratio in grass silage-based diets increased milk production with no effect on daily fat yield, leading to 13% lower milk fat concentration. The effect of FC ratio on MFG size was moderate. It did not affect the volume-weighted diameter in grass silage-based diets, although LG lowered the volume-surface diameter of MFG in the size class >1 µm compared with HG. Compared with HG, feeding LG moderately decreased the biohydrogenation of 18:2n-6, leading to a higher level of polyunsaturated fatty acids in milk fat. Feeding RC lowered milk fat concentration and daily milk fat yield compared with grass silage-based diets. The volume-weighted diameter of MFG in the size class >1 µm was smaller in RC milk compared with grass silage-based diets. Feeding RC increased the flow of 18:3n-3 at the omasum by 2.4-fold and decreased the apparent ruminal 18:3n-3 biohydrogenation compared with grass silage-based diets despite similar intake of 18:3n-3. It also resulted in the lowest amount of saturated FA and the highest amounts of cis-9 18:1, 18:3n-3, and polyunsaturated FA in milk. In conclusion, LG decreased milk fat content and induced minor changes in MFG size distribution compared with HG, whereas RC lowered milk fat production, altered milk FA composition to nutritionally more beneficial direction, and led to smaller MFG compared with grass silage-based diets.     

Shared genes, shared experiences, and similarity of personality: Data from 14,288 adult Finnish co-twins.

Similarities for Extraversion (E) and Neuroticism (N) scale scores from the Eysenck Personality Inventory were evaluated in 7,144 adult twin pairs, drawn from the population-based Finnish Twin Cohort, as a function of the co-twins' genetic resemblance, gender, age, and the frequency of their social interaction with each other. To separate effects of shared genes from those of shared experience, we performed hierarchical multiple regressions of double-entry data matrices. Results establish the predictive significance of both genetic and experiential influences: Genetic effects remained significant when tested after the effects of social contact were first removed; conversely, for N scores, the effects of social contact remained significant when assessed after genetic influences were first removed. These findings establish genetic variance in major dimensions of adult personality but assign a significant role to common experience as well. The first finding constructively replicates reports by others; the second challenges the widespread assumption that shared experiences have a negligible impact on sibling similarity in adult personality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

X-ray microbeam transmission/fluorescence method for non-destructive characterization of tungsten coated carbon materials

Tungsten erosion, its subsequent transport and redeposition are of great interest, because a full tungsten divertor is foreseen to be used during the deuterium–tritium operational phase of ITER. The erosion of tungsten and carbon marker layers was extensively studied in the outer divertor of ASDEX Upgrade (AUG), and work is currently in progress to completely replace the existing JET CFC tiles with tungsten-coated tiles within the JET ITER-like wall project. The need for fast and non-destructive method which allows the quantitative determination of the thickness of a tungsten coating on a carbon material on large areas led us to evaluate a combined absorption/fluorescence X-ray (XRTF) technique. The method can provide fast analysis, high spatial resolution and a material selective detection of deposited layers and inclusions. It was applied on W coated fine grain graphite (FGG) tiles from AUG's divertor. It is proved that the method is able to provide information about the uniformity of the tungsten coating on a graphite or CFC substrate whilst the technique can be used to determine the thickness of the tungsten and other marker materials coatings. It represents a unique instrument for the post-mortem analysis of the coatings.     

Distribution of microbes in supercritical CO2 extraction of sea buckthorn (Hippopha? rhamnoides) oils

 The distribution of vegetative microbial cells and their spores in a supercritical CO₂ extraction process was studied. The seed and flesh/skin fractions of the press residue of sea buckthorn berries (Hippopha? rhamnoides) from a juice factory were used as raw materials. A pilot-scale extraction plant was operated at 30 MPa at temperatures of 40 and 60°C. The number of yeasts, moulds and bacteria in the pulp/skin fraction, in the extraction residues, in the extracted oils as well as in the water phases separated from the extracted oils was estimated by the spread plate technique. The microbial content of the flesh/skin material was increased in some extractions by the addition of bacterial spores. In general, the extraction process led to a decrease in the bacterial count of the extracted material, whereas no microbial growth was detected in the oils extracted or in the water phases separated from them. Neither yeasts nor moulds were found in any samples after the extraction process. The microbial status of seed oil and flesh/skin oil obtained by industrial-scale CO₂ extraction at 40°C and at 30 MPa before and after gelatine encapsulation remained unchanged. This proves that supercritical CO₂ can be used to manufacture edible oil products free of living micro-organisms and their spores. Received: 14 May 1996     

The biological leaching of an auriferous pyrite ore

The oxidation of an auriferous pyrite ore sample was evaluated in biological leaching experiments for subsequent gold recovery via cyanidation. In batch cultures, organisms derived from the mine site oxidized pyrite and ferrous iron at pH values as low as pH 0.6. The recovery of gold was variable in shake flask experiments. In stirred tank bioreactor leaching, gold recovery was proportional to the extent of iron dissolution by bioleaching. The leaching of arsenic from the sample was also directly proportional to iron dissolution.