Structural Diversity of Streptococcal Mutans Synthesized under Different Culture and Environmental Conditions and Its Effect on Mutanase Synthesis

Abstract

Streptococcal mutans synthesized under different conditions by growing cultures or by their glucosyltransferases were shown to exhibit a great structural and property diversity. Culturing and environmental factors causing structural differences in mutans were specified. All of the obtained biopolymers (76 samples) were water-insoluble and most of them (72) had a structure with a predominance of α-(1→3)-linked glucose (i.e., the content of α-(1→3)-linkages in the glucan was always higher than 50%, but did not exceed 76%). An exception were four glucans containing more than 50% of α-(1→6)-sequences. In these structurally unique mutans, the ratio of α-(1→3)- to α-(1→6)-bonds ranged from 0.75 to 0.97. Aside from one polymer, all others had a heavily branched structures and differed in the number of α-(1→3), α-(1→6), and α-(1→3,6) linkages and their mutual proportion. The induction of mutanase production in shaken flask cultures of Trichoderma harzianum by the structurally diverse mutans resulted in enzyme activities ranging from 0.144 to 1.051 U/mL. No statistical correlation was found between the total percentage content of α-(1→3)-linkages in the α-glucan and mutanase activity. Thus, despite biosynthetic differences causing structural variation in the mutans, it did not matter which mutan structures were used to induce mutanase production.

Enzymes in therapy of biofilm‐related oral diseases

“…Mutans and dextrans are particularly important glucans in the formation of dental plaque. Mutans have a highly branched structure with main chains composed of glucose molecules linked with (1→3)‐α bonds and (1→6)‐α‐glucosidic linkages in their side chains . Dextrans are also high molecular weight polymers of glucose containing numerous consecutive (1→6)‐α‐linkages in their backbone and side chains, which begin from the (1→3)‐α‐linkage .…”

Purification and properties of an α-(1 → 3)-glucanase (EC 3.2.1.84) from Trichoderma harzianum and its use for reduction of artificial dental plaque accumulation.

“…The activity of the purified α-(1→3)-glucanase toward different substrates (1%, w/v) was determined under optimum assay conditions. Streptococcal α-glucans (mutans) were synthesized from sucrose using cell-free glucosyltransferases of streptococci (S. sobrinus/downei CCUG 21020 -mutans DTM, B 3 and D 6 ; S. sobrinus GCM 20381 -mutan A 10 ; S. sobrinus CAPM 6070 -mutan A 15 ) under different condi-Purification of α-(1→3)-glucanase from Trichoderma harzianum tions (Wiater et al, 2012). Fungal alkali-soluble α-(1→3)glucans were prepared according to the method described by Kiho et al (1994).…”