Effect of different types of calcium carbonate on the lactic acid fermentation performance of Lactobacillus lactis

• Recycled CaCO3 from purification possesses unique features.
• Lactic acid productivity increased by 33.17% using recycled CaCO3.
• Recycled CaCO3 has improved pH-regulatory ability.
• Recycled CaCO3 can accelerate the growth of Lactobacillus lactis-11.
• The existence of a direct interaction between the cell and the recycled CaCO3 particle was confirmed.

The effect of two different types of calcium carbonate on lactic acid fermentation was investigated in this study. The results showed that the fermentation performance of calcium carbonate greatly improved when the recycled particle was used instead of the original particle. The improved fermentation was evidenced by the pH of the broth, the enhanced production of lactic acid (increase of 33.17%) and the enhanced cell dry weight (CDW, increase of 19.24%). Analysis of the composition and structure of calcium carbonate revealed that the recycled compound possesses several unique features that allow it to maintain a higher pH and provide nitrogen during fermentation. The experimental results indicated that a higher pH value and the addition of nitrogen could increase the fermentation performance, but these factors were not sufficient to explain the original findings. Macroscopic and microscopic studies confirmed that direct interactions, such as absorption and particle entrance, occurred between Lactobacillus lactis-11 and the recycled calcium carbonate particles. These direct interactions may provide a favorable microenvironment to the cell.