Oral Biol Res.  2022 Sep;46(3):99-105. 10.21851/obr.46.03.202209.99.

Characterization of hemin-binding of oral streptococci

• Kim EJ
• Lee SY

• KMID: 2533990
• DOI: http://doi.org/10.21851/obr.46.03.202209.99

Abstract

Certain pathogenic bacteria obtain iron for growth through heme or heme compounds. Streptococci are gram-positive bacteria that reside in the mouth and require iron for growth. However, the iron accumulation mechanism in streptococci remains unknown. Therefore, this study investigated the hemin-binding properties of streptococci to confirm the potential of oral streptococci to obtain iron through heme compounds. The hemin-binding ability of streptococci was evaluated by incubation with hemin and subsequent measurement of the optical density of the supernatant to determine the amount of hemin bound by the bacteria using the hemin concentration standard curve. The hemin-binding of streptococci was proportional to the concentration of bacteria (Streptococcus gordonii) and hemin added. However, when a high hemin concentration of up to 60 μg/mL was added, the amount of hemin bound by S. gordonii remained almost unchanged. The incubation temperature had no significant effect on hemin-binding, but pretreatment with trypsin and protease decreased hemin-binding. Additionally, we experimentally confirmed that S. gordonii could use hemin for growth. This study demonstrated that streptococci possess hemin-binding sites and can acquire iron through hemin.

Keyword

Hemin; Iron; Streptococcus