Streptococcus mutans and Streptococcus sanguinis have been associated with the development of caries, oral infections and bacteremia. In fact, there are only a few case reports in the literature describing bacteremia in relation to S. mutans and S. sanguine. The objective of this study was purification and characterization of curvatcin LHM from Lactobacillus curvatus, evaluation of its antibacterial activity against S. mutans and S. sanguinis and evaluation the effect of minimum inhibitory concentration of curvatcin LHM and chlorohexidine on biofilm formation as well as, study the effect of L. curvatus as immunomodulator. Curvatcin LHM was isolated and purified from L. curvatus culture. Purified and crude curvatcin LHM exhibited bactericidal action against S. mutans and S. sanguinis isolates in vitro. Significant differences (P < 0.05) were found in viable count between pre and posttreatment of S. mutans and S. sanguinis biofilms with curvatcin LHM and chlorohexidine. Unlike chlorohexidine, curvatcin LHM left no viable bacterial cells in biofilm of S. mutans and S. sanguinis. Bagg Albino laboratory breed (BALB/c) mice were orally administered with L. curvatus for 2 weeks and then intravenously injected with S. mutans and S. sanguinis. Four days before inoculation, microbiological and immune response were determined, serum proinflammatory cytokine, TNF-α, IL-10 and IL-6 were evaluated by ELISA. The L. curvatus treatment significantly decreased S. mutans and S. sanguinis in the organs and blood of mice with bacteremia as compared with the non-L. curvatus-treated mice (P < 0.05). Furthermore, proinflammatory cytokine, TNF-α, IL-10 and IL-6, were significantly higher in groups pretreated with L. curvatus (P < 0.05) prior streptococcal infection. These data suggest that curvatcin LHM may be a good alternative to chlorhexidine as an additive for teeth-protective materials. Curvatcin LHM cotreatment with chlorohexidine might help to increase the anticariogenic efficacy of chlorohexidine. On the other hand, L. curvatus can be serving as direct modulator of proinflammatory responses.

Widespread release of cyanide from industrial activities represents a significant environmental challenge due to its acute toxicity and adverse effects on biological systems. In response to this concern, this study focused on the production of rhodanese from Kocuria rhizophila under submerged fermentation conditions and the assessment of its relevance for cyanide detoxification applications. A soil-derived Gram-positive bacterium was isolated and identified as Kocuria rhizophila based on morphological traits, biochemical profile-based VITEK 2 analysis, and 16S rRNA gene sequencing. Preliminary screening confirmed rhodanese production with an activity of 0.968 RU/mL. Under cyanide-induced submerged fermentation, enzyme production followed a growth-associated pattern and reached maximal activity at 40 h under optimized conditions (35 °C, pH 8.0). Partial purification using sequential precipitation and chromatographic steps enhanced enzyme purity, and SDS–PAGE analysis of the final fraction revealed protein bands at approximately 40, 140, and 260 kDa. Biochemical characterization showed Km values of 33.9 mM for KCN and 19.7 mM for sodium thiosulfate, with a Vmax of ~5.6 µmol min⁻¹ mL⁻¹ for KCN and optimal activity at pH 7–8 and 35 °C. Functional assays demonstrated efficient cyanide detoxification, achieving >85% conversion of KCN, ~92% of NaCN, and 65–77% of Ca (CN)₂ within 60 min in vitro. Collectively, these findings demonstrate that Kocuria rhizophila represents a promising microbial source of rhodanese with efficient cyanide-detoxifying activity, highlighting its potential for biotechnological and environmental remediation applications.

Cancer and diabetes are prevalent global disorders that affect large segments of the population and exert substantial burdens on national economies, quality of life, and morbidity and mortality indicators. In this study, the therapeutic potential of methionine gamma-lyase (MGL) was investigated as a candidate anticancer, antidiabetic, and anti-inflammatory agent. MGL was produced following the isolation of Streptomyces maritimus from soil, and both starch nitrate agar and a modified formulation were employed as differential and selective media to support biochemical identification of the bacterial isolates. Enzyme purification was achieved through sequential application of acetone precipitation, ammonium sulfate fractionation, gel filtration chromatography, and ion-exchange chromatography, yielding a substantially enriched protein as confirmed by SDS-PAGE analysis. The biological activities of MGL were assessed using an MTT cytotoxicity assay, an in vitro α-amylase inhibitory assay, and an in vitro anti-inflammatory assay to determine its suitability as an effective and cost-efficient alternative to commonly used protocols. The findings demonstrated that only 14% of Hep-2 cells remained viable at the highest concentration of MGL extract, erythrocyte hemolysis inhibition reached 29% at the lowest concentration tested, and the enzyme exhibited an IC₅₀ of 78 µg mL-1 for α-amylase inhibition, suggesting a promising capacity to attenuate postprandial blood glucose excursions in individuals with diabetes.