Diversity and antimicrobial products of culturable coral-associated actinomycetes in Hainan.

The increasing concern over multidrug resistance in pathogens has led to an ongoing search for novel antibiotics derived from soil actinobacteria. In this current investigation, actinobacteria were isolated from the rhizosphere of bamboo plants collected within the Megamalai forest of the Western Ghats in the Theni zone of Tamil Nadu, India. These actinobacteria were subjected to characterization, and their growth conditions were optimized to enhance the production of bioactive compounds. To assess antibacterial properties, the isolated Actinobacteria underwent testing using the agar plug method. The strain exhibiting notable antibacterial activity underwent further characterization through 16s rRNA gene sequencing and subsequent phylogenetic analysis. Employing response surface methodology (RSM), cultural conditions were fine-tuned. Bioactive compounds were extracted from the culture medium using ethyl acetate, and their antibacterial and antioxidant effects were evaluated through disc diffusion and DPPH radical scavenging methods, respectively. Ethyl acetate extracts were analyzed by using FT-IR and GC-MS techniques. In total, nine strains of Actinobacteria were isolated from the rhizosphere soil of bamboo. Among these, strain BS-16 displayed remarkable antibacterial activity against three strains: Staphylococcus aureus (19 mm), Bacillus subtilis (12 mm), and Streptococcus pyogenes (10 mm). This strain was identified as Streptomyces sp. The optimal conditions for bioactive compound production were determined as follows: malt extract (10 g), yeast extract (5 g), dextrose (5 g), pH 6.5, and temperature 30 °C. After a 7-day incubation period, the results showed a 6% increase in production. The ethyl acetate fraction derived from strain BS-16 exhibited dose-dependent antibacterial and antioxidant activities. FT-IR and GC-MS analyses revealed the presence of active compounds with antibacterial effects within the extract. Consequently, further investigation into the BS-16 strain holds promise for scaling up the production of bioactive compounds possessing antibacterial and antioxidant properties.

The purpose of this research to determine the fractions of Chick Weed which has strong antibacterial activity against bacteria test categories of Bacillus subtilis and Vibriocholerae.determine the value of the minimum in hibitory concentration(MIC) of the active fraction antibacterial Chick Weed.This research was carried out in August up to November 2016. The method used in this study were extracted by maceration, fractionation by liquid-liquid fractionation, separation by column chromatography fractions, antibacterial activity test by theKirby-Bauermethod, while the determination of minimum in hibitory concentration by dilution broth,with test bacteria Bacillus subtilis and Vibriocholerae.The data presented in tabular form based on the average value and percent.The results of this study showed that the methanol extract Chick Weed active against test bacteria Bacillus subtilis and Vibrio cholerae. Fractionation which has strong category to standard antibiotics are methanol fraction by fraction column S4.The concentration MIC1000;500;250;125;62.5;31.2515.62; 7.81 ppm. The minimum in hibitory concentration column fractions S4 to test bacteria Vibrio cholerae of 62.5 ppm gives half the antibacterial activity of the antibacterial activity of standard antibiotics streptomycin and penicillin,tetracycline while giving a quarter activity. It can be concluded that the active fraction of methanol extractisa methanol fraction by fraction column S4 to test bacteria Vibrio cholerae.Keywords: Chick Weed, Minimum Inhibitory Concentration (MIC), active compound, Bacillus subtilis, Vibriocholera.

Mangrove-derived microorganism is a promising and important resource of novel natural products and lead compounds for drug discovery. This study aimed to find microbial secondary metabolites with novel structures. Based on the bioactive-guided screening of mangrove-derived actinomycetes, <italic>Streptomyces</italic> sp. GP3T5 was studied owing to its antibacterial, antibiofilm and anti-fungi activities. Three compounds (1-3) were isolated from the fermentation broth by organic solvent extraction, reversed-phase chromatography, Sephadex LH20 gel chromatography, and preparative high-performance liquid chromatography. Their structures were identified as pyrisulfoxin A (compound 1), collismycin A (compound 2), and echinomycin A (compound 3), respectively, via high resolution electrospray ionization mass spectroscopy (HRESIMS), nuclear magnetic resonance (NMR), ultraviolet (UV) spectroscopy. The activity evaluation of compounds 1-3 revealed that all three compounds showed antibacterial and antibiofilm activities. Compound 3 showed potent antibacterial activity against foodborne pathogens with minimum inhibitory concentrations (<inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:msub><mml:mrow><mml:mi>ρ</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">M</mml:mi><mml:mi mathvariant="normal">I</mml:mi><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:msub></mml:math></inline-formula>) of 0.06 μg/mL for <italic>Listeria monocytogenes</italic> and <italic>Streptococcus agalactiae</italic>. The minimum biofilm inhibitory concentrations (<inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:msub><mml:mrow><mml:mi>ρ</mml:mi></mml:mrow><mml:mrow><mml:mi mathvariant="normal">M</mml:mi><mml:mi mathvariant="normal">B</mml:mi><mml:mi mathvariant="normal">I</mml:mi><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:msub></mml:math></inline-formula>) of compounds 1-3 against <italic>Acinetobacter baumannii</italic> were 32 μg/mL, 16 μg/mL, and 1 μg/mL, respectively. Compounds 2 and 3 showed good antifungal activity against plant pathogenic fungi, with half maximal inhibitory concentrations (IC₅₀) ≤ 10 μg/mL and ≤ 1 μg/mL, respectively. In conclusion, these results on strain GP3T5 derived from mangroves provide valuable insights for further exploration of bioactive compounds from mangrove soil microorganisms.

Streptococcus agalactiae (S.agalactiae), also known as group B Streptococcus (GBS), is a highly infectious pathogen. Prolonged antibiotic usage leads to significant issues of antibiotic residue and resistance. Chelerythrine (CHE) is a naturally occurring benzophenidine alkaloid and chelerythrine chloride (CHEC) is its hydrochloride form with diverse biological and pharmacological activities. However, the antibacterial mechanism of CHEC against GBS remains unclear. Thus, this study aims to investigate the in vitro antibacterial activity of CHEC on GBS and elucidate its underlying mechanism. The antibacterial effect of CHEC on GBS was assessed using inhibitory zone, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays, as well as by constructing a time-kill curve. The antibacterial mechanism of CHEC was investigated through techniques such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM), measurement of alkaline phosphatase (AKP) activity, determination of Na+ K+, Ca2+ Mg2+-adenosine triphosphate (ATP) activity, observation of membrane permeability, and analysis of intracellular reactive oxygen species (ROS) and mRNA expression levels of key virulence genes. The results demonstrated that the inhibition zone diameters of CHEC against GBS were 14.32 mm, 12.67 mm, and 10.76 mm at concentrations of 2 mg/mL, 1 mg/mL, and 0.5 mg/mL, respectively. The MIC and MBC values were determined as 256 μg/mL and 512 μg/mL correspondingly. In the time-kill curve, 8 × MIC, 4 × MIC and 2 × MIC CHEC could completely kill GBS within 24 h. SEM and TEM analyses revealed significant morphological alterations in GBS cells treated with CHEC including shrinkage, collapse, and leakage of cellular fluids. Furthermore, the antibacterial mechanism underlying CHEC's efficacy against GBS was attributed to its disruption of cell wall integrity as well as membrane permeability resulting in extracellular release of intracellular ATP, AKP, Na+ K+, Ca2+ Mg2+. Additionally CHEC could increase the ROS production leading to oxidative damage and downregulating mRNA expression levels of key virulence genes in GBS cells. In conclusion, CHEC holds potential as an antimicrobial agent against GBS and further investigations are necessary to elucidate additional molecular mechanisms.

Multidrug-resistant and biofilm-forming pathogens have become a global health challenge, contributing to persistent and hard-to-treat infections. The objective of this study was to characterize an active metabolite produced by a novel halo-thermophilic Streptomyces sp. CBN-1 that exhibits potent antibacterial and antibiofilm activities using a combined in-silico and experimental approach. In this study, a halo-thermophilic Streptomyces sp. CBN-1 strain was selected for its ability to grow in 10% NaCl at 40°C. This strain was identified using phenotypic characterizations and 16S rRNA gene sequence analysis as Streptomyces rochei NRRL B-2410 with 99.15% similarity. An active metabolite, CBNa-1, was extracted using n-butanol solvent from ISP2 broth medium and purified by HPLC. Structural characterization using electrospray ionization mass spectrometry and NMR spectroscopy identified CBNa-1 as an aromatic heterocyclic compound regulated by non-ribosomal peptide synthetase (NRPS) and type II polyketide synthase (PKS) genes. It exhibited potent activity with minimum inhibitory concentrations (MIC) ranging from 4 to 5µg/mL and minimum biofilm inhibitory concentrations (MBIC50%) at ½ MIC. Additionally, in-silico docking analyses showed that CBNa-1 had stronger binding affinities from - 8.7 to -8.1kcal/mol with isoleucyl-tRNA synthetase, glucosamine-6-phosphate synthase, penicillin-binding protein 1a, type II DNA topoisomerases, and quorum sensing compared to antibiotics (-5.7 to -7.9kcal/mol). Furthermore, molecular dynamic (MD) simulation showed the stability of the protein-ligand complex under physiological conditions. This study reports the first identification of CBNa-1, a metabolite from prokaryotic cells, with potent antibacterial and anti-biofilm properties to combat nosocomial infections caused by MDR pathogens, including bacteria resistant to third-generation cephalosporins.

The aim of this present study was to determine the phytochemicals and antibacterial activity of Borreria stachydea whole plant using chloroform and methanol as the extracting solvents. The powdered sample was subjected into soxhlet extraction by hot continuous percolation. The extracts were concentrated at 40oC by vacuum evaporation and later exposed to air drying to give dried crude extracts. Phytochemical screening of the extracts was performed using standard procedures available in literature. Antibacterial activity of B. stachydea was determined using agar well diffusion method, while the Minimal Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) of the extracts against bacteria were determined by broth dilution technique. Phytochemical screening of the extracts revealed the presence of tannins, flavonoids, carbohydrates, cardiac glycosides, terpenes and steroids. Both extracts were active against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis. Comparatively, methanolic extract contained more phytochemicals but lower values of zones of inhibition than chloroform extract. At a concentration of 10 mg/ml, both methanolic extract and sparfloxacin (a standard antibiotic) used as control in this study exhibited similar antibacterial activity against Bacillus subtilis. The results of this investigation revealed that Borreria stachydea contains phytochemicals that are potential sources of antibacterial agents.Keywords: Borreria stachydea, Extract, Phytochemical, Antibacterial, MIC, MBC

A novel actinomycete, designated strain GIMN4.001(T), was isolated from the rhizosphere of tomato plants grown in Guangzhou, China. The strain produced greyish white aerial mycelia, lactic acid and a large quantity of double diamond-shaped crystals on potato dextrose agar and yeast extract-malt extract agar. The colour of the substrate mycelium was not sensitive to pH. Microscopic observations revealed that strain GIMN4.001(T) produced verticillate chains of cylindrical spores. Chemotaxonomic data confirmed that strain GIMN4.001(T) belonged to the genus Streptomyces. Melanin pigments were not produced. No antibacterial activity was observed against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis or Candida albicans, but inhibitory activity was observed against Penicillium citrinum. 16S rRNA gene sequence analysis revealed that strain GIMN4.001(T) was related most closely to Streptomyces morookaense ATCC 19166(T) (98.9 % similarity) and Streptomyces lavenduligriseus ATCC 13306(T) (98.7 %). Levels of DNA-DNA relatedness between strain GIMN4.001(T) and the type strains of these species were low (14-20 %). Furthermore, strain GIMN4.001(T) could be differentiated from S. morookaense, S. lavenduligriseus and other closely related species of the genus Streptomyces based on morphological, physiological and biochemical characteristics. On the basis of its physiological and molecular properties, strain GIMN4.001(T) is considered to represent a novel species of the genus Streptomyces, for which the name Streptomyces lacticiproducens sp. nov. is proposed. The type strain is GIMN4.001(T) (=CCTCC M208214(T)=NRRL B-24800(T)).

The Abundance and Diversity of Soil Actinomycetes from Ciremai National Park West Java. Actinomycetes of soil samples from Mount Ciremai National Park, West Java were been isolated by Sodium Dodecyl Sulphate Yeast Extract (SDS YE) method in Humic Acid Vitamin Agar (HVA) medium. The colonies of actinomycetes were counted based on Total Plate Count (TPC). Diversity of actinomycetes were identified based on spore, chain spore, pigmentation, hypha and aerial hypha formation. The abundance of actinomycetes were 3,50 x104 – 71,50 x104 CFU/g soil. Seven genus of actinomycetes were found, they were Streptomyces, Nocardia, Micromonospora, Microbiospora, Actinomadura, Actinoplanes, and Microtetraspora. Most of them were distributed in 900 until 2500 m height above sea level. Streptomyces only known in 2700, 2900 and 3057 m above sea level. Population of Streptomyces were predominant in all soil types according to height, but were highest in 2500 m asl. Key words: Actinomycetes, fungi, Mount Ciremai, diversity, abundance.

The diversity of culturable endophytic actinomycetes related to plants and especially medicinal plants are isolated and characterized. The increased colonization and distribution of endophytic actinomycetes in plants have been reported in many studies. Endophytic actinomycetes belong to different genera are distributed in plants species such as Streptomyces, which is the dominant genus, Micromonospora, Microbispora, Nocardiopsis, Rhodococcus and Nocardia. Moreover, there are many novel strains had been described belong to these genera. Endophytic actinomycetes seem to contribute with plant development and displaying beneficial traits that can be exploited in plant maintenance, substances supplements, protection and defense. Colonization of endophytic actinomycetes in plant tissues are largely influenced by plant species and the environmental factors surrounding the host plants such as soil pH, water content, rainfall, soil salinity, and temperatures. Some endophytic actinomycetes may occur in low numbers and sometimes in localized positions within the plant. Thus, this review summarizes an aspect of the diversity and colonization of endophytic actinomycetes, including their mechanism of action, importance, and isolation and identification methods.

Antibacterial and antifungal activities of polyketide metabolite from marine Streptomyces sp. AP-123 and its cytotoxic effect

Chemical composition of Mentha pulegium and Rosmarinus officinalis essential oils and their antileishmanial, antibacterial and antioxidant activities

Aims: The purpose of this study was to investigate the antibacterial and anticandidal activities of new flavonoids from Streptomyces sp. HK17 which was isolated from the root tissue of Curcuma longa Linn. Study Design: Experimental study. Place and Duration of Study: The study was carried out at the Department of Microbiology and Department of Chemistry, Faculty of Science, Silpakorn University, between February and May 2014. Methodology: The major active ingredients from the crude extract were purified by silica gel column chromatography, thin-layer chromatography. The diameters of the zones of inhibition and the Minimum Inhibitory Concentration (MIC) were determined using the paper disc diffusion and the microbroth dilution methods respectively. Results: The crude extract and purified compounds were tested for their antibacterial activity against Staphylococcus aureus ATCC25932, Bacillus cereus ATCC7064 and Bacillus subtilis ATCC6633, Escherichia coli ATCC10536 and Pseudomonas aeruginosa ATCC27853 and anticandidal activity against Candida albicans ATCC190088. The crude extract showed the highest activity against S. aureus and C. albicans, with MIC values of 32 µg/ml. The purified compounds 3 showed the lowest MIC (32 µg/ml) and Minimum Microbicidal Concentration (MMC) (128 µg/ml) against S. aureus and C. albicans with corresponding large diameter of the zone of inhibitions (25.5 and 25.2 mm respectively). Conclusion: This study has shown that the new flavonoids were first isolated and identified. These flavonoids produced by Streptomyces sp. HK17 have potential in antibacterial and anticandidal activities.

Antibacterial resistance has become a major global public health issue. Pathogens such as Staphylococcus aureus, Bacillus subtillis, Escherichia coli, and Klebsiella pneumoniae associated with most community infections are linked with antibiotic resistance. Curcuma xanthorrhiza is a traditional medicine used to prevent and cure bacterial infection. This study evaluated the antibacterial and antibiofilm activities of C. xanthorrhiza essential oil (EO) against selected clinical isolates, as well as their interaction with conventional antibiotics. Chromatographic analysis revealed that the principal constituents of C. xanthorrhiza EO are α-curcumene and β-curcumene, representing 22.11 and 23.39% of the oil content, respectively. Curzerene, camphor, and xanthorrhizol also made up a significant fraction of the essential oils extract, accounting for more than 4.5%. C. xanthorrizha EO had considerable antibacterial activity against Bacillus subtillis with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of 7.8 and 15.6 µg/mL, but exhibited moderate activity against Staphylococcus aureus with MIC value of 31.2 µg/mL. Moreover, when used in combination, C. xanthorrhiza EO increased the antibacterial activity of ampicillin, resulting in a synergistic effect. C. xanthorrhiza EO inhibited the formation of biofilm in B. subtillis and S. aureus. C. xanthorrhiza EO significantly reduced the viability of established biofilm in B. subtillis and S. aureus at 15.6 µg/mL (2 MIC) and 125 µg/mL (4 MIC). The results showed that C. xanthorrhiza EO had potent antibacterial activity, inhibiting biofilm and increasing the effect of ampicillin against clinical isolate pathogen particularly B. subtillis.

Antibiotic resistance has been reported as one of the world's most critical public health problems. Recent investigations have demonstrated that the venom of some species of snakes has antimicrobial and anticancer activities. The purpose of this study was to examine the antibacterial activity of Persian horned viper venom toward Escherichia coli, Bacillus subtilis, and Staphylococcus aureus bacteria and also investigate antitumor effects of concentrations of venom with higher antibacterial activity in a human hepatocellular liver carcinoma cell line (HepG2) to evaluate the potential use of its components as antimicrobial and anticancer agents. Bactericidal activity of crude venom in concentrations of 6.25-400 μg/ml was performed using MTT reduction, minimum inhibitory concentration (MIC), agarwell diffusion, and disc diffusion methods. Tetracycline (50 μg/ml) was used as a standard antibiotic. Cytotoxic effect in HepG2 cells was measured by MTT reduction assay and confirmed with neutral uptake assay following exposure of cells with different concentrations of venom (50-400 μg/ml). The apoptotic effect was investigated using the comet assay. Our findings demonstrated that venom displays higher inhibitory effects against Gram-positive bacteria as compared to Gramnegative. Furthermore, venom showed anticancer activity on the HepG2 cell line through induction of apoptosis and necrosis. The results of this study confirmed that the venom of Persian horned viper induces antibacterial and anticancer effects. These properties make the venom of this viper a potential source for isolation of effective molecule(s) having antibacterial and antitumor activity.

Effects of tillage and inorganic fertilizers on culturable soil actinomycete communities and inhibion of fungi by specific actinomycetes