Exopolysaccharide production by Streptococcus thermophilus SY: production and preliminary characterization of the polymer.

AIMS: To evaluate the effect of yeast extract (YE) concentration, temperature and pH on growth and exopolysaccharide (EPS) production in a whey-based medium by Streptococcus thermophilus SY and to characterize the partially purified EPS. METHODS AND RESULTS: Factorial experiments and empirical model building were used to optimize fermentation conditions and the chemical composition, average molecular weight (MW) and rheological properties of aqueous dispersions of the EPS were determined. Exopolysaccharide production was growth associated and was higher (152 mg l(-1)) at pH 6.4 and 36 degrees C with 4 g l(-1) YE. High performance size exclusion chromatography of the partially purified EPS showed two peaks, with a weight average MW of 2 x 10(6) and 5 x 10(4), respectively. The EPS was a heteropolysaccharide, with a glucose : galactose : rhamnose ratio of 2 : 4.5 : 1. Its water dispersions had a pseudoplastic behaviour and showed a higher viscosity of xanthan solutions. SIGNIFICANCE AND IMPACT OF THE STUDY: The fermentation conditions and some properties of an EPS produced by Strep. thermophilus, a dairy starter organism, were described.

IP videoconferencing using a quality of service public network.

Videoconferencing in the medical world has been successfully used for quite a few years. Nevertheless it has not spread significantly in daily use. Some of the problems rely on the infrastructure needed to set up a video session: one or more ISDN lines or a fast Internet connection. The first is not easily available everywhere in a building; the latter is rarely so fast to allow for a smooth operation with no quality drops. The use of Videonet, the first European commercial public Internet link with guaranteed Quality of Service (QoS), has the potential to be a breakthrough in videoconferencing. We describe this new system and its applications, with the first tests in a hospital environment. Our results show that there are still problems to be solved in order to achieve a quality comparable to ISDN.

Evolution of microbial populations and biogenic amine production in dry sausages produced in Southern Italy.

AIMS: To evaluate the occurrence and evolution of biogenic amines during ripening of fermented sausages and their relationship with physico-chemical and microbiological properties of the product. METHODS AND RESULTS: Salsiccia and Soppressata were obtained from artisanal and industrial plants in Basilicata and pH, aW, microbial counts and biogenic amine content were measured. A high variability in amine content was observed. 2-Phenylethylamine and histamine were rarely found, while the tyramine, putrescine and cadaverine content increased during ripening. No correlation was found between individual biogenic amine content, microbial counts or physico-chemical parameters. CONCLUSION: Starter cultures did not necessarily prevent the production of biogenic amines whose total contents were usually higher in Soppressata, a product with a larger diameter and aW compared with Salsiccia. SIGNIFICANCE AND IMPACT OF THE STUDY: Literature findings on biogenic amine content and the evolution of microbial populations were confirmed. Normal ranges for amine content in Salsiccia and Soppressata are reported.

Phenotypic diversity of lactic acid bacteria isolated from fermented sausages produced in Basilicata (Southern Italy).

AIMS: to evaluate the evolution of lactic acid bacteria (LAB) populations in traditional fermented sausages (salsiccia and soppressata) produced in artisanal and industrial plants in Basilicata (Southern Italy). METHODS AND RESULTS: Four hundred and fourteen lactic acid bacteria (LAB) cultures were isolated from samples of sausages at different stages of ripening. A phenotypic characterization of the isolates was carried out using a set of 28 tests, and 34 clusters were identified at the 80% similarity level using hierarchical cluster analysis. Of the isolates 50% were identified as Lactobacillus sakei (with several biotypes), 22% as Pediococcus spp. (mainly Ped. pentosaceus), 7% as Leuconostoc (Leuc. carnosum, Leuc. gelidum, Leuc. pseudomesenteroides), 6% as Lact. plantarum, 1% as Lact. curvatus. Other lactobacilli, including unidentified species, were present in lower numbers. CONCLUSION: The phenotypic diversity and composition of the LAB flora varied as a function of the production plant, product type and ripening time. SIGNIFICANCE AND IMPACT OT THE STUDY: A new procedure based on bootstrapping and Multidimensional Scaling was successfully used to obtain a graphical representation of the evolution of the LAB populations.

Effects of pH, temperature and NaCl concentration on the growth kinetics, proteolytic activity and biogenic amine production of Enterococcus faecalis.

In this work, the combined effects of temperature, pH and NaCl concentration on the growth dynamics of Enterococcus faecalis EF37, its proteolytic activity and its production of biogenic amines have been studied. The effects of the selected variables have been analysed using a Central Composite Design. The production of biogenic amines, under the adopted conditions, was found to be mainly dependent on the extent of growth of E. faecalis. Its proteolytic activity was not a limiting factor for the final amine production, because in the system studied (skim milk) an excess of precursors was guaranteed. Quantitatively, the most important biogenic amine produced was 2-phenylethylamine but substantial amounts of tyramine were detected in all the samples. This work confirms that the main biological feature influencing the biogenic amine formation is the extent of growth of microorganisms, like E. faecalis, characterised by decarboxylase activity. In the traditional and artisanal cheeses produced using raw milk, enterococci usually reach levels of 10(7) cells/g. With this perspective, it is important that the presence of biogenic amines due to the activities of these microorganisms is maintained within safe levels, without affecting the positive effects of enterococci on the final organoleptic characteristics of the cheese.

A survey of yeasts in traditional sausages of southern Italy.

The evolution of the yeast population during manufacturing and ripening of 'salsiccia sotto sugna', a typical salami of the Lucania region (southern Italy), was investigated. Four different batches, produced in four farms in Lucania, were studied. Each batch showed a specific yeast population, and the most frequently isolated yeasts belonged to Debaryomyces hansenii and its anamorph Candida famata, and Rhodotorula mucilaginosa. Yarrowia lipolytica was isolated from three sausage batches. The Y. lipolytica isolates were further characterised, in particular for their lipolytic activity on pork fat. Lipolytic activity was maximal at pH 5.5, with oleic and palmitic acids as major free fatty acids produced. The use of randomly amplified polymorphic DNA-polymerase chain reaction allowed the detection of a high genetic heterogeneity among the isolates phenotypically assigned to the species Y. lipolytica.

Biogenic amine formation and oxidation by Staphylococcus xylosus strains from artisanal fermented sausages.

Fifty strains of Staph. xylosus, isolated from artisanal fermented sausages in Southern Italy (Lucania region) were tested to verify their potential to produce or degrade biogenic amines. Twenty-six strains analysed were not able to form amines, but seven had the potential to produce spermine and/or spermidine and, at lower levels, tryptamine and tyramine. By contrast, about 80% of the strains that did not possess amino acid decarboxylase activity, exhibited an ability to degrade histamine. The greatest histamine-oxidase activity was present in the strains S81 (100% degradation), S206 (93%), S79 (68%) and S90 (53%). The strain S142 exhibited a remarkably high potential to oxidase tyramine and histamine, reducing the initial concentrations by 63 and 47%, respectively.

Accessing a WWW reference library of 3D models of pathological organs to support medical education.

A major aspiration of the medical community is to use multimedia databases to disseminate important research or clinical information and for education. We describe a WWW reference library of 3D models of human organs containing pathological and normal organs organised in cases, together with a variety of educational and supporting tools. Although the emphasis is chiefly on the teaching of medical students and the continuing education of physicians, the library is also a potentially-valuable resource for diagnostic investigation. This paper describes the environment, methodologies and tools for supporting 3D models in medical education. The prototype of the system is currently being completed; the full system is scheduled for public access in the year 2000 through multimedia publishers.

Assessing the use of low cost PC-based ISDN videoconferencing in hospital training.

A course on Italian safety rules and regulations has been delivered to the personnel of a University clinic using videoconferencing, based on an ISDN-2 connection through a multimedia PC. The goal was to evaluate the efficacy of this technology for the training of hospital personnel. To assess it, the trainees were divided into two groups, one at the trainer's site and the other in the University. Comparing the evaluating questionnaires that both groups were asked to complete at the end of each session (based on the comprehension of the subject taught), significant differences were found only when the quality of images was very poor (for technical reasons) or the level of interaction was low. The price/performance ratio was considered good, but there are some technical and psychological problems that must be taken in account before using videoconferencing for training.

Organisation, transmission, manipulation of pathological human organs on the WWW.

The paper describes an integrated methodology for the development of a WWW computer system which addresses issues of the organisation, retrieval and manipulation of 3D volumetric models of pathological human organs. The library of organs is distributed on the WWW since medical expertise and needs are typically expensive resources and also because many pathological conditions are often restricted to local diffusion. Users are provided with a WWW viewer for interactive manipulation of the models of the organs. The system supports low-cost MS-Windows 32 platforms and requires no specialised hardware. Early results demonstrate that the compression techniques employed provide near real-time response for retrieval/manipulation, not only over high-speed expensive network lines, but also over low/medium network connections.

A distributed support system for medical and nursing students.

The Internet provides resources for physicians, but there isn't yet a comprehensive support system for medical and nursing students. Moreover the knowledge of English language is often scarce in young Italian students, so most of the available resources are not really useful. This project aims at the establishment of a distributed framework of interactive courses and mentoring facilities among a group of Italian Medical and Nursing Schools.