Abstract
The article deals with studying the antimicrobial efficiency of finely ground metallurgical slags, such as granulated blast-furnace slag with specific surface areas of 340 (1Sa) and 520 m2/kg (1Sb), air cooled blast-furnace slag (2S), demetallized steel slag (3S), calcareous ladle slag (4S), and copper slag (5S). The efficiency was tested on microbial representatives, such as: Gram-positive bacteria—Bacillus subtilis, Staphylococcus aureus, Micrococcus luteus; Gram-negative bacteria—Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens; yeasts—Candida utilis, Rhodotorula glutinis; and microscopic filamentous fungi—Aspergillus niger, Penicillium funiculosum, Chaetomium globosum, Alternaria alternata, Trichoderma viride, Cladosporium herbarum. The efficiency was determined by dilution methods in agar growth media so that the resulting concentration of the tested slags was 10, 20, 40, and 60%. The antibacterial efficiency of the slags decreased in the order: S4 > S3 > S2 > S1a = S1b > S5, while their anti-yeast efficiency decreased in the order S4 > S1a = S1b = S3 > S2 > S5. Microscopic filamentous fungi were selectively sensitive to the slags; therefore, there is only an approximate order of efficiency of S4 > S3 = S1a = S1b > S5 > S2. Application of metallurgical slags into building materials and products provide them with increasing resistance against biodeterioration.
Highlights
Biocorrosion of concretes, mortars, and building materials and products is a serious problem wherever the conditions suitable for particular microorganisms occur
The antimicrobial efficiencies of slags regarding inhibition of growth of selected bacteria are given in Table 3; the antimicrobial efficiencies of slags regarding inhibition of growth of selected yeasts are given in Table 4; and the antimicrobial efficiencies of slags regarding inhibition of growth of selected filamentous fungi are given in Table 5, respectively
The growth extent of selected bacteria and yeasts is expressed by mathematical signs (, +, ++, +++), and the degree of growth of selected filamentous fungi is expressed relatively by the percentage (%) of the sample surface covered by fungi colonies
Summary
Biocorrosion of concretes, mortars, and building materials and products is a serious problem wherever the conditions suitable for particular microorganisms occur. Biocorrosion, as a specific type of chemical corrosion, is caused by various biogenic organic acids and mineral acids (sulphuric acid, H2 SO4 , and nitric acid, HNO3 ), as well as by corrosive hydrogen sulphide, H2 S, and ammonia, NH3 , which result from the metabolic activity of microorganisms [1,2,3,4]. These aggressive metabolites react mainly with calcareous components of concrete and mortar stone, with development of their non-binding calcareous salts. Fungal strains belonging to the genera Alternaria, Cladosporium, Epicoccum, Fusarium, Mucor, Penicillium, Pestalotiopsis, and Trichoderma were isolated
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