초록
<P><B>Highlights</B></P><P>► <SMALL>D</SMALL>-Lactic acid production by <I>Lactobacillus delbrueckii</I> were carried using Ca(OH)<SUB>2</SUB>, NH<SUB>4</SUB>OH, and NaOH as neutralizing agents. ► Broken rice was used for production of <SMALL>D</SMALL>-lactic acid by simultaneous saccharification and fermentation processes. ► Ca(OH)<SUB>2</SUB> gave the highest productivity of lactic acid (3.59gl<SUP>−1</SUP>h<SUP>−1</SUP>) compared to NH<SUB>4</SUB>OH and NaOH. ► Divalent cation (Ca<SUP>+</SUP>) was more effective in neutralizing the cultures compared to monovalent (Na<SUP>+</SUP> and NH3+) cations.</P> <P><B>Abstract</B></P><P>Effects of Ca(OH)<SUB>2</SUB>, NH<SUB>4</SUB>OH, and NaOH as neutralizing agents for efficient recovery of lactic acid was investigated. Lactic acid was produced from broken rice in a simultaneous saccharification and fermentation (SSF) process with <I>Lactobacillus delbrueckii</I>. Consumption of glucose (from broken rice) by the cells and the cell growth were the best with Ca(OH)<SUB>2</SUB> among the three neutralizing agents used. Maximum productivities of lactic acid reached with Ca(OH)<SUB>2</SUB>, NH<SUB>4</SUB>OH, and NaOH were 3.59gl<SUP>−1</SUP>h<SUP>−1</SUP>, 1.51g1<SUP>−1</SUP>h<SUP>−1</SUP>, and 1.40gl<SUP>−1</SUP>h<SUP>−1</SUP>, respectively. Ca(OH)<SUB>2</SUB> reduced the lactate molarity of the fermentation broth, and thus resulted in the highest lactic acid productivity. Furthermore, it was apparently clear that divalent cation (Ca<SUP>2+</SUP>) was more effective in neutralizing the cultures compared to monovalent (Na<SUP>+</SUP> and NH<SUB>3</SUB><SUP>+</SUP>) cations.</P>