title: Bacillus sphaericus LMG 22257 is physiologically suitable for self-healing concrete.
abstract: The suitability of using a spore-forming ureolytic strain, Bacillus sphaericus, was evaluated for self-healing of concrete cracks. The main focus was on alkaline tolerance, calcium tolerance, oxygen dependence, and low-temperature adaptability. Experimental results show that B. sphaericus had a good tolerance. It can grow and germinate in a broad range of alkaline pH. The optimal pH range is 7 ∼ 9. High alkaline conditions (pH 10 ∼ 11) slow down but not stop the growth and germination. Oxygen was strictly needed during bacterial growth and germination, but not an essential factor during bacterial urea decomposition. B. sphaericus also had a good Ca tolerance, especially at a high bacterial concentration of 108cells/mL; no significant influence was observed on bacterial ureolytic activity of the presence of 0.9M Ca2+. Furthermore, at a low temperature (10 °C), bacterial spores germinated and revived ureolytic activity with some retardation. However, this retardation can be counteracted by using a higher bacterial concentration and by supplementing yeast extract. It can be concluded that B. sphaericus is a suitable bacterium for application in bacteria-based self-healing concrete.
authors.affiliation: Magnel Laboratory for Concrete Research, Ghent University, Technologiepark Zwijnaarde 904, 9052, Ghent, Belgium.|Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
authors.forename: Jianyun
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Materials and Environment, Delft University of Technology, Stevinweg 1, 2628, CN, Delft, The Netherlands.
authors.forename: Henk M
authors.initials: HM
authors.lastname: Jonkers
authors.affiliation: Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
authors.forename: Nico
authors.initials: N
authors.lastname: Boon
authors.affiliation: Magnel Laboratory for Concrete Research, Ghent University, Technologiepark Zwijnaarde 904, 9052, Ghent, Belgium. nele.debelie@ugent.be.
authors.forename: Nele
authors.initials: N
authors.lastname: De Belie
mesh_terms: D000468:Alkalies / Q000378:metabolism; D001407:Bacillus / Q000254:growth & development / Q000502:physiology*; D002119:Calcium Carbonate / Q000737:chemistry / Q000378:metabolism*; D003252:Construction Materials / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology; D010100:Oxygen / Q000378:metabolism; D013171:Spores, Bacterial / Q000254:growth & development; D014508:Urea / Q000378:metabolism
chemical_list: D000468:Alkalies; D014508:Urea; D002119:Calcium Carbonate; D010100:Oxygen
keywords: Alkaline tolerance; Bio-CaCO3; Ca tolerance; Oxygen dependence; Temperature adaptability; Ureolytic activity