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Congresso Brasileiro de Microbiologia 2023
 		Resumo: 1017-1

1017-1

ENHANCING CALCIUM PRECIPITATION IN BIOCONCRETE: THE SYNERGISTIC EFFECT OF OXALATE AND CARBONATE

Autores:
Bruno Damasceno Oliveira (UFRGS - Universidade Federal do Rio Grande do Sul) ; João Vitor Borowski (UFRGS - Universidade Federal do Rio Grande do Sul) ; Giovana Parcianello Viana (UFRGS - Universidade Federal do Rio Grande do Sul) ; Augusto Schrank (UFRGS - Universidade Federal do Rio Grande do Sul) ; Marilene Vainstein (UFRGS - Universidade Federal do Rio Grande do Sul)

Resumo:
Buildings are continuously exposed to weather conditions and human activities, making them susceptible to various issues, including forming cracks. Such cracks pose a significant threat to the longevity of reinforced concrete structures. Innovative technologies have emerged to address this concern, and one promising approach involves using bacteria capable of facilitating microbiologically induced calcium carbonate precipitation (MICP). In this study, oxalate initiated immediate precipitation, and its potential was tested in combination with bacteria and essential nutrients. Bacillus subtilis and Sporosarcina pasteurii were inoculated overnight in LB and TSB + urea media. To immediately initiate precipitation, oxalate was used. Bacteria were inoculated overnight in LB and TSB + urea media. The test solutions were separated into two groups (values in mM): i) B. subtilis, sodium oxalate 113, calcium lactate 56.5, calcium nitrate 282.3, ii) S. pasteurii, sodium oxalate 113, urea 333, calcium nitrate 338.8, in addition to control without bacteria. The OD600 was measured and adjusted to 0.1 for the inoculums. Precipitated calcium was indirectly measured using the OCPC reagent via OD575 spectrophotometry at days 0 and 5. The results demonstrated that media containing calcium oxalate precipitated approximately 123.4 mM, about ⅔ of the total calcium at time 0 (200 mM). Notably, media containing S. pasteurii displayed considerable calcium precipitation, reaching 42 mM in the presence of urea and 184 mM with urea and oxalate, with pH values of 7 (without oxalate) and 9.5 (with oxalate). The combined use of oxalate and carbonate demonstrated increased calcium precipitation efficiency, particularly in the medium containing urea, oxalate, and S. pasteurii. These findings hold the potential for enhancing the healing properties of bioconcrete and contributing to the long-term durability of buildings.

Palavras-chave:
 bioconcrete, oxalate & carbonate, calcium precipitation, Sporosarcina pasteurii, Bacillus subtilis


Agência de fomento:
CAPES, CNPq e FAPERGS