Microbiological investigation on black crusts from open-air stone monuments of Bologna (Italy).
Samples of black crusts taken from open-air stone monuments in Bologna dating back to between the twelfth and the nineteenth century were considered. The microbiological test procedures isolated from a high number of chemoorganotrophic bacteria, each of the samples although it was expected to find chemo-lithotrophic (specially sulfur-oxidizing and nitrifying) bacteria on account of the great amounts of sulphur, carbon, nitrogen dioxides and ammonia in the air. Sporogenous and asporogenous species were found among the isolated bacteria: the first were recognized as Bacillus subtilis, Bacillus brevis, Bacillus licheniformis, Bacillus mycoides and Bacillus megaterium; the latter were Corynebacterium glutamicum, Actinomyces sp., Alcaligenes denitrificans subsp. denitrificans, Flavobacterium breve, Acinetobacter calcoaceticus, Enterobacter cloacae, Pseudomonas stutzeri. These species were differently associated in the samples studied with a frequency of more than sixty-four per cent. This finding leads us to believe that their presence in the black crusts is not occasional, but the result of an ecologically significant process of colonization. Although behavioural tests (solubilization of calcium carbonate, of calcium sulphate and marble dust) did not reveal lithic activity among the bacteria studied, one can presume that their behaviour in nature - as a more or less complex microbial consortium - can be totally different and exert a decomposing action with regard to several minerals, most of them acidify the media in which they develop.
Turtura
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GC
Institute of Agricultural Microbiology and Technology, University of Bologna, Italy.
Perfetto
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A
Lorenzelli
P
P
D001108:Architecture; D015373:Bacterial Typing Techniques; D001673:Biodegradation, Environmental; D004783:Environmental Microbiology; D016946:Gram-Negative Aerobic Rods and Cocci / Q000302:isolation & purification*; D006094:Gram-Positive Bacteria / Q000302:isolation & purification*; D007558:Italy; D008903:Minerals; D013171:Spores, Bacterial
D008903:Minerals