Effect of bone meal (calcium phosphate) amendments on metal release from contaminated soils--a leaching column study.

Metal-contaminated soil may be remediated in situ by the formation of highly insoluble metal phosphates if an appropriate phosphorus (P) source can be found. Leaching column experiments have been carried out to assess the suitability of bone meal as such a source. Bone meal additions reduced metal release from a contaminated soil, increased soil and leachate pH and decreased soil leachate toxicity. Minimal P leaching occurred from the soil. The data are consistent with a proton consuming bone meal (calcium phosphate) dissolution reaction followed by the formation of metal phosphates. Although, no metal phosphates were observed to form using X-ray diffraction of scanning electron microscopy this could be due to their low concentration. Relatively low (1:50 bone meal:soil) concentrations of fine (90-500 microns) bone meal would appear to be an effective treatment for metal-contaminated soils.

Lead mineral transformation by fungi.

Pyromorphite (Pb5(PO4)3Cl), the most stable lead mineral under a wide range of geochemical conditions [1], can form in urban and industrially contaminated soils [2] [3] [4] [5]. It has been suggested that the low solubility of this mineral could reduce the bioavailability of lead, and several studies have advocated pyromorphite formation as a remediation technique for lead-contaminated land [3] [5] [6], if necessary using addition of phosphate [6]. Many microorganisms can, however, make insoluble soil phosphate bioavailable [7] [8] [9] [10], and the solubilisation of insoluble metal phosphates by free-living and symbiotic fungi has been reported [11] [12] [13] [14] [15]. If pyromorphite can be solubilised by microbial phosphate-solubilising mechanisms, the question arises of what would happen to the released lead. We have now clearly demonstrated that pyromorphite can be solubilised by organic-acid-producing fungi, for example Aspergillus niger, and that plants grown with pyromorphite as sole phosphorus source take up both phosphorus and lead. We have also discovered the production of lead oxalate dihydrate by A. niger during pyromorphite transformation, which is the first recorded biogenic formation of this mineral. These mechanisms of lead solubilisation, or its immobilisation as a novel lead oxalate, have significant implications for metal mobility and transfer to other environmental compartments and organisms. The importance of considering microbial processes when developing remediation techniques for toxic metals in soils is therefore emphasised.

Myofibril content of histochemical fibre types in rat skeletal muscle.

A modification of the histochemical method for myosin ATPase was used to determine the myofibril complement, mean myofibril size and myofibrillar packing of defined muscle fibre types in rat skeletal muscle. Fast muscle fibres (Types IIA and IIB) were found to have smaller myofibrils and a lower packing density than slower (Type I) fibres. These findings were discussed with respect to their relevance in estimations of muscle strength from histological and histochemical preparations of muscle cross-sections.

Butirosin, a new aminoglycosidic antibiotic complex: bacterial origin and some microbiological studies.

Butirosin, a new aminoglycosidic antibiotic complex, was produced by submerged fermentation with each of two strains of Bacillus circulans. A paper-disc, agar-diffusion assay which employs Escherichia coli (P-D 04863) as the test organism has been developed. Shaken-flask and stirred-jar fermentations in a medium containing glycerol, soybean meal, meat peptone, ammonium chloride, and calcium carbonate reach titers of 500 to 700 mug of butirosin base per ml. Butirosin is active against several gram-positive and gram-negative bacteria including Pseudomonas aeruginosa.