Taxonomic study of Streptomyces sp. strain 34-1

The present work is a part of a complex study of Streptomyces sp. strain 34-1 - a producer of trypsin and trypsin-like protease inhibitors with antiviral effect. The taxonomically significant properties of the strain were examined according to the International Streptomycetes Project (ISP). The identification of the strain was based on Nonomura's key. The morphological, cultural, physiological and biochemical characteristics of Streptomyces sp. strain 34-1 were compared with the references for similar streptomycetes species. The strain was identified as Streptomyces chromofuscus and designated as S. chromofuscus 34-1

Taxonomic study of Streptomyces sp. strain 34-1

The present work is a part of a complex study of Streptomyces sp. strain 34-1 - a producer of trypsin and trypsin-like protease inhibitors with antiviral effect. The taxonomically significant properties of the strain were examined according to the International Streptomycetes Project (ISP). The identification of the strain was based on Nonomura's key. The morphological, cultural, physiological and biochemical characteristics of Streptomyces sp. strain 34-1 were compared with the references for similar streptomycetes species. The strain was identified as Streptomyces chromofuscus and designated as S. chromofuscus 34-1

Comparative determination of antimicrobial activity of the Balkan endemic species Stachys thracica Davidov during the process of ex situ conservation

Stachys thracica Davidov – Thracian woundwort is a Balkan endemic plant included in The Red Data Book of Bulgaria with conservational status “rare”. The plants from genus Stachys have a long history of use to treat various diseases, inflammatory conditions, coughs, ulcers, genital tumors, and infected wounds. Due to its limited distribution the information on the biological activity and chemical composition of S. thracica is rather scarce. The aim of the present research is the comparative determination of the antimicrobial activity of methanolic extracts obtained from in situ wild, in vitro cultivated and ex vitro adapted S. thracica plants. The in vitro shoot culture of the Thracian woundwort was maintained in hormone-free MS medium under controlled environmental conditions. The methanolic extracts from in situ, in vitro cultivated and ex vitro adapted S. thracica plants were active mainly against Gram-negative bacteria. All three extracts showed equal activity against Acinetobacter calcoaceticus. The establishment of in vitro shoot culture and its subsequent adaptation in ex vitro conditions was an appropriate alternative approach for the ex situ conservation of S. thracica as well as for the study of its biological activity

INFLUENCE OF THE LONG-TERM PRESERVATION ON SOME BIOLOGICAL FEATURES OF THREE STREPTOMYCETES STRAINS, PRODUCERS OF ANTIBIOTIC SUBSTANCES

The influence of long-term preservation in lyophilized state on the survival, the morphology and antibiotic activity of three streptomycetes strains Streptomyces galbus (F) subsp. achromogenes 695, Str. albogriseolus 444 and Streptomyces sp. T-741 was studied. It was established that viability of the strains depended not only on the conditions of lyophilization but also on the physiological state and strain features of the cultures. The spores of the strain 695, 444 and T-741 remained viable 13, 21 and 8 years respectively. At the same time an increase of the polymorphism of the strains 695 and 444 and appearance of new morphological types was observed. The method of lyophilization was suitable also for long-term storage of antibiotic activity of the three strains. The activity was retained to 80-90% from initial one

INFLUENCE OF THE LONG-TERM PRESERVATION ON SOME BIOLOGICAL FEATURES OF THREE STREPTOMYCETES STRAINS, PRODUCERS OF ANTIBIOTIC SUBSTANCES

The influence of long-term preservation in lyophilized state on the survival, the morphology and antibiotic activity of three streptomycetes strains Streptomyces galbus (F) subsp. achromogenes 695, Str. albogriseolus 444 and Streptomyces sp. T-741 was studied. It was established that viability of the strains depended not only on the conditions of lyophilization but also on the physiological state and strain features of the cultures. The spores of the strain 695, 444 and T-741 remained viable 13, 21 and 8 years respectively. At the same time an increase of the polymorphism of the strains 695 and 444 and appearance of new morphological types was observed. The method of lyophilization was suitable also for long-term storage of antibiotic activity of the three strains. The activity was retained to 80-90% from initial one

Outstanding Antibacterial Activity of Hypericum rochelii—Comparison of the Antimicrobial Effects of Extracts and Fractions from Four Hypericum Species Growing in Bulgaria with a Focus on Prenylated Phloroglucinols

Microbial infections are by no means a health problem from a past era due to the increasing antimicrobial resistance of infectious strains. Medicine is in constant need of new drugs and, recently, plant products have had a deserved renaissance and garnered scientific recognition. The aim of this work was to assess the antimicrobial activity of ten active ingredients from four Hypericum species growing in Bulgaria, as well as to obtain preliminary data on the phytochemical composition of the most promising samples. Extracts and fractions from H. rochelii Griseb. ex Schenk, H. hirsutum L., H. barbatum Jacq. and H. rumeliacum Boiss. obtained with conventional or supercritical CO2 extraction were tested on a panel of pathogenic microorganisms using broth microdilution, agar plates, dehydrogenase activity and biofilm assays. The panel of samples showed from weak to extraordinary antibacterial effects. Three of them (from H. rochelii and H. hirsutum) had minimum inhibitory concentrations as low as 0.625–78 mg/L and minimum bactericidal concentrations of 19.5–625 mg/L against Staphylococcus aureus and other Gram-positive bacteria. These values placed these samples among the best antibacterial extracts from the Hypericum genus. Some of the agents also demonstrated very high antibiofilm activity against methicillin-resistant S. aureus. Ultra-high-performance liquid chromatography–high-resolution mass spectrometry revealed the three most potent samples as rich sources of biologically active phloroglucinols. They were shown to be good drug or nutraceutical candidates, presumably without some of the side effects of conventional antibiotics

Outstanding Antibacterial Activity of <i>Hypericum rochelii</i>—Comparison of the Antimicrobial Effects of Extracts and Fractions from Four <i>Hypericum</i> Species Growing in Bulgaria with a Focus on Prenylated Phloroglucinols

Microbial infections are by no means a health problem from a past era due to the increasing antimicrobial resistance of infectious strains. Medicine is in constant need of new drugs and, recently, plant products have had a deserved renaissance and garnered scientific recognition. The aim of this work was to assess the antimicrobial activity of ten active ingredients from four Hypericum species growing in Bulgaria, as well as to obtain preliminary data on the phytochemical composition of the most promising samples. Extracts and fractions from H. rochelii Griseb. ex Schenk, H. hirsutum L., H. barbatum Jacq. and H. rumeliacum Boiss. obtained with conventional or supercritical CO2 extraction were tested on a panel of pathogenic microorganisms using broth microdilution, agar plates, dehydrogenase activity and biofilm assays. The panel of samples showed from weak to extraordinary antibacterial effects. Three of them (from H. rochelii and H. hirsutum) had minimum inhibitory concentrations as low as 0.625–78 mg/L and minimum bactericidal concentrations of 19.5–625 mg/L against Staphylococcus aureus and other Gram-positive bacteria. These values placed these samples among the best antibacterial extracts from the Hypericum genus. Some of the agents also demonstrated very high antibiofilm activity against methicillin-resistant S. aureus. Ultra-high-performance liquid chromatography–high-resolution mass spectrometry revealed the three most potent samples as rich sources of biologically active phloroglucinols. They were shown to be good drug or nutraceutical candidates, presumably without some of the side effects of conventional antibiotics