Low-cost cultivation and sporulation of alkaliphilic Bacillus sp. Strain AK13 for self-healing concrete

Minyoung Hong, Wonjae Kim, Woojun Park

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


The alkaliphilic, calcium carbonate precipitating Bacillus sp. strain AK13 can be utilized in concrete for self-repairing. A statistical experimental design was used to develop an economical medium for its mass cultivation and sporulation. Two types of screening experiment were first conducted to identify substrates that promote the growth of the AK13 strain: the first followed a one-factor-at-a-time factorial design and the second a two-level full factorial design. Based on these screening experiments, barley malt powder and mixed grain powder were identified as the substrates that most effectively promoted the growth of the AK13 strain from a range of 21 agricultural products and by-products. A quadratic statistical model was then constructed using a central composite design and the concentration of the two substrates was optimized. The estimated growth and sporulation of Bacillus sp. strain AK13 in the proposed medium were 3.08 ± 0.38 × 108 and 1.25 ± 0.12 × 108 CFU/ml, respectively, which meant that the proposed low-cost medium was approximately 45 times more effective than the commercial medium in terms of the number of cultivatable bacteria per unit price. The spores were then powdered via a spray-drying process to produce a spore powder with a spore count of 2.0 ± 0.7 × 109 CFU/g. The AK13 spore powder was mixed with cement paste, yeast extract, calcium lactate, and water. The yeast extract and calcium lactate generated the highest CFU/ml for AK13 at a 0.4:0.4 ratio compared to 0.4:0.25 (the original ratio of the B4 medium) and 0.4:0.8. Twenty-eight days after the spores were mixed into the mortar, the number of vegetative cells and spores of the AK13 strain had reached 106 CFU/g within the mortar. Cracks in the mortar under 0.29 mm were healed in 14 days. Calcium carbonate precipitation was observed on the crack surface. The mortar containing the spore powder was thus concluded to be effective in terms of healing micro-cracks.

Original languageEnglish
Pages (from-to)1982-1992
Number of pages11
JournalJournal of microbiology and biotechnology
Issue number12
Publication statusPublished - 2019

Bibliographical note

Funding Information:
This research was supported by a grant (19SCIP-B103706-05) from Construction Technology Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government and a grant from the National Institute of Biological Resources (NIBR), funded by the Ministry of Environment (MOE) of the Republic of Korea (NIBR201920201).

Publisher Copyright:
Copyright © 2019 by The Korean Society for Microbiology and Biotechnology.


  • Agricultural products
  • Calcium carbonate precipitation
  • Crack healing material
  • Economical medium
  • Spray dryer
  • Statistical design of experiments

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology


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