Bacterial communities of tyre monofill sites: growth on tyre shreds and leachate.

AIMS: To investigate bacterial communities of tyre monofill sites, colonization of tyre material by bacteria and the effect of tyre leachate on bacteria. METHODS AND RESULTS: Culturable bacteria were isolated from buried tyre shreds and identified using fatty acid methyl ester analysis. Isolates belonged to taxonomic groups such as Bacilli, Actinobacteria, Clostridia, Flavobacteria, beta and gamma-proteobacteria. For tyre material colonization experiments, Bacillus megatarium, Bacillus cereus, Hydrogenophaga flava, Janthinobacterium lividum, Cellulosimicrobium cellulans, Arthrobacter globiformis (isolated from tyre shreds or leachate at the study site); Escherichia coli and Acidithiobacillus ferrooxidans were used. Beakers containing tyre shreds and artificial rain water were inoculated with a given bacterial culture, incubated at room temperature and sampled at regular intervals. 4',6-diamidino-2-phenylindole (DAPI) staining followed by epifluorescent microscopy was used to enumerate bacteria in samples. Of the bacteria tested, B. megatarium, J. lividum, E. coli, C. cellulans and A. globiformis exhibited the most extensive colonization of the tyre shreds. However, the extent of colonization varied among bacteria. Response to tyre leachate was also examined using B. cereus and J. lividum. Both bacteria increased in abundance due to the addition of leachate. CONCLUSIONS: Bacteria associated with buried tyre shreds were identified and found to include typical soil and freshwater organisms. The majority of indigenous isolates grew on tyre material (or leachate) suggesting that they play an active role in the ecology of these sites and that their potential role in tyre degradation should be explored. SIGNIFICANCE AND IMPACT OF THE STUDY: This study provides information on bacterial communities of tyre-waste disposal sites, explores the interaction between tyre material and bacteria and identifies bacteria that could be involved in or employed for recycling tyre-waste.

In-situ self-assembling protein polymer gel systems for administration, delivery, and release of drugs.

Sequential block copolymers consisting of tandem repetition of amino acids have been constructed and genetically produced based on the natural repeating structures of silk and elastin protein. Combinations of silklike and elastinlike amino acid sequence blocks in a high molecular weight protein polymer are used to confer properties similar to those observed with hard block and soft block segmented polyurethanes. A certain subset of these silk-elastinlike protein compositions, termed ProLastins, will undergo an irreversible solution to gel transition in physiological, aqueous solution. The transition occurs over time and can be controlled by temperature, solution conditions, and additives which either prevent or promote hydrogen bond-mediated chain crystallization. The process involves no covalent crosslinking. Characterization of the gelling properties of various ProLastin compositions and their ability to release compounds which are incorporated directly into the gels are presented.

Student health services at four rural colleges: implications for healthcare reform.

This study investigated services available at health centers at four rural colleges. It also investigated the healthcare accessible to students at those institutions if college health services were unavailable. The authors used a survey and interview procedure to establish the existence of healthcare resources in two adjacent communities and to identify barriers to student use. Findings from the study indicate that, for many students attending rural colleges, the student health center may be the only source of primary healthcare available. The data support the need to include student health centers at rural colleges in the national healthcare reform agenda because closing any one of these schools' health centers could result in a healthcare disaster for some students.