Abstract Stachys species belonging to Lamiaceae family have been used for medicinal purposes since ancient times. The aim of the present study was to investigate the chemical compositions and antibacterial, anti-tyrosinase activities of the essential oil of Stachys macrostachya. The essential oil was prepared by hydrodistillation method using a Clevenger-type apparatus and chemical composition was determined by gas chromatography (GC). The antibacterial activity of essential oil was performed by the disc diffusion and microdilution broth method against five Gram-positive and two Gram-negative bacteria. The tyrosinase inhibitory activity was evaluated by minor modifications of Masuda’s method. According to the results of GC analyses, twenty-three compounds were identified representing 91.9% of the total volatile composition. The main compounds were germacrene D (12.2%), globulol (10.9%), α-pinene (9.7%), and valencene (7.6%). The present study showed that the tested essential oil of S. macrostachya exhibited antibacterial activity against Acinetobacter baumannii (MIC 62.50 μg/mL) and tyrosinase inhibition activity (IC50 22.86 ± 0.82 μg/mL). These results suggest that the essential oil could be exploited as a potential source of natural antimicrobial agents of this bacterium as well as tyrosinase inhibitors.

Abstract In the current study, twenty-eight bacterial strains were isolated from home-made yogurt samples from Ağrı Province, Turkey. The bacterial strains were identified by conventional and molecular techniques. Among the twenty- eight isolates, seventeen isolates were identified according to the 16 S rDNA region and determined to belong to five different genus including Sphingomonas (8 isolates), Burkholderia (5 isolates), Lactobacillus (2 isolates), Lactococcus (1 isolate), Staphylococcus (1 isolate). In this study, the presence of Burkholderia in home-made yogurt samples were reported for the first time, whereas Sphingomonas was detected for the second time. We also investigated the carbonate (CaCO3 and MgCO3) and silicate (CaSiO3 and MgSiO3) dissolving potential of seventeen bacterial isolates. Among these seventeen bacterial isolates, fifteen bacterial isolates have CaCO3-dissolving and 10 bacterial isolates have MgCO3-dissolving potential. The silicates dissolution ability was relatively less than that of carbonates dissolving. We observed that six bacterial isolates have CaSiO3 and only two bacterial isolates have MgSiO3 dissolution abilities. In conclusion, this work clearly shows the diversity of bacteria existing in fermented cow milk samples in Ağrı Province, Turkey, which could be considered as valuable sources for lactic acid bacteria (LAB) isolation and further probiotic potential.