Antibacterial and Antibiofilm Activities of Crude Extract of Lasiodiplodia pseudotheobromae IBRL OS-64 against Foodborne Bacterium, Yersinia enterocolitica

The antibacterial and antibiofilm activities of crude extract of Lasiodiplodia pseudotheobromaeIBRL OS-64 was studied and tested against a foodborne pathogenic bacterium, Yersinia enterocolitica. The ethylacetate extract exhibited favorable antibacterial activity with the zone of inhibition was 20.3±0.6 mm compared to dichloromethane (15.0±0.3 mm) and butanol (9.0±0.3 mm) extracts. Minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) values of the extract were 125 and 250 μg/mL, respectively. Structural degeneration studies through scanning electron microscopy (SEM) and transmission electron microscope (TEM) micrographs exhibited major abnormalities that occurred on thebacterial cells after exposureto the extract were complete alterations in their morphology and collapsed of the cells beyond repair. The findings showed that the extract possesses antibiofilm activity against the initial and preformed biofilm of Y. enterocoliticawith the highest inhibition value of 69.12% and 58.70%, respectively The results also revealed the initial biofilm was more susceptible to the extract as compared to pre-formed biofilm. The light microscopy (LM) and SEM photomicrographs proved that thefungal extract significantly eliminates extracellular polysaccharide (EPS) matrices and hinder the attachment of the bacterial cells for biofilm formation. Therefore, the current study suggested the ethyl acetate crude extract from an endophytic fungus, L. pseudotheobromae IBRL OS-64 may be an effective antibacterial and anti-biofilm agent to treat foodborne pathogens

Antimicrobial Activities of Daucus Carota Seeds on Selected Pathogenic Micro-organisms

Background: The antibacterial/antifungal toxicity of Daucus carota (carrot) seeds was evaluated using selected multi-drug resistant bacteria and yeast of clinical origin. Methods: The active constituents of the Daucus carota seeds were extracted using conventional Plant Tissue Homogenization method using cold distilled water, Ethanol and Methanol as solvents. Varying concentrations (5-250 mg/ml) of the three extracts were assayed for antimicrobial activity against the selected isolates- Salmonella typhi, Staphylococcus aureus, Escherichia coli, Klebseilla pneumoniae and Candida albicans; the agar well diffusion method was used. The antibiogram profile of the organisms was also obtained through disc diffusion method. Results: Similar activity was observed in the methanolic and ethanolic extracts while cold distilled water showed no activity on any of the isolates. The antibiotic susceptibility results showed that the isolates used are highly multi-drug resistant. Ofloxacin exhibited the most pronounced activity against all the isolates. Gentamicin and erythromycin both showed activity on Escherichia coli and Salmonella typhi. Lower concentrations of both extracts presented no inhibitory effects on the test organisms, thus resulting in high MIC values recorded for both extracts. Also, the extracts showed no bactericidal action against the isolates.  Conclusions: Observations from this research therefore affirm that Daucus carota seeds possess antimicrobial properties that may be explored as a source of future antimicrobial compounds.

Avaliação da atividade antimicrobiana da planta Tradescantia pallida Munt (Taboquinha Roxa) / Evaluation of antimicrobial activity of the Tradescantia pallida Munt plant (Taboquinha Roxa)

RESUMO O objetivo deste estudo foi pesquisar o efeito antimicrobiano in vitro do extrato hidroalcóolico das folhas Tradescantia pallida Munt conhecida como Taboquinha roxa. Foram realizados testes em meio sólido, onde não observou qualquer halo de inibição, e o método de microdiluição, em que os resultados foram expressivos, com determinação da Concentração Inibitória Mínima (CIM) e Concentração Bactericida Mínima (CBM), com resultados em diferentes concentrações. Foram utilizadas cepas padrão de bactérias Gram positivas e Gram negativas. De acordo com os resultados, sugere-se que essa planta apresenta um potencial antimicrobiano.

ABSTRACT The aim of this study was to investigate the in vitro antimicrobial effect of the hydroalcoholic extract of the Tradescantia pallida Munt leaves,known as Taboquinha roxa. The tests were both conducted on solid mean, where it was not observed any zone of inhibition, and by the micro dilution method, in which the results of the Minimum Inhibitory Concentration (MIC) and the Minimum Bactericidal Concentration (MBC) were significant and related with the different concentrations. Standard strains of bacteria type Gram positive and Gram negative were employed. According to the results, this plant has an antimicrobial potential.

Screening antimicrobial activity of various extracts of Urtica dioica

Urtica dioica or stinging nettle is traditionally used as an herbal medicine in Western Asia. The current study represents the investigation of antimicrobial activity of U. dioica from nine crude extracts that were prepared using different organic solvents, obtained from two extraction methods: the Soxhlet extractor (Method I), which included the use of four solvents with ethyl acetate and hexane, or the sequential partitions (Method II) with a five solvent system (butanol). The antibacterial and antifungal activities of crude extracts were tested against 28 bacteria, three yeast strains and seven fungal isolates by the disc diffusion and broth dilution methods. Amoxicillin was used as positive control for bacteria strains, vancomycin for Streptococcus sp., miconazole nitrate (30µg/mL) as positive control for fungi and yeast, and pure methanol (v/v) as negative control. The disc diffusion assay was used to determine the sensitivity of the samples, whilst the broth dilution method was used for the determination of the minimal inhibition concentration (MIC). The ethyl acetate and hexane extract from extraction method I (EA I and HE I) exhibited highest inhibition against some pathogenic bacteria such as Bacillus cereus, MRSA and Vibrio parahaemolyticus. A selection of extracts that showed some activity was further tested for the MIC and minimal bactericidal concentrations (MBC). MIC values of Bacillus subtilis and Methicillin-resistant Staphylococcus aureus (MRSA) using butanol extract of extraction method II (BE II) were 8.33 and 16.33mg/mL, respectively; while the MIC value using ethyl acetate extract of extraction method II (EAE II) for Vibrio parahaemolyticus was 0.13mg/mL. Our study showed that 47.06% of extracts inhibited Gram-negative (8 out of 17), and 63.63% of extracts also inhibited Gram-positive bacteria (7 out of 11); besides, statistically the frequency of antimicrobial activity was 13.45% (35 out of 342) which in this among 21.71% belongs to antimicrobial activity extracts from extraction method I (33 out of 152 of crude extracts) and 6.82% from extraction method II (13 out of 190 of crude extracts). However, crude extracts from method I exhibited better antimicrobial activity against the Gram-positive bacteria than the Gram-negative bacteria. The positive results on medicinal plants screening for antibacterial activity constitutes primary information for further phytochemical and pharmacological studies. Therefore, the extracts could be suitable as antimicrobial agents in pharmaceutical and food industry.

Urtica dioica u ortiga se utiliza tradicionalmente como medicina herbaria en el oeste de Asia. En esta investigación se estudia la actividad antimicrobiana de nueve extractos crudos de U. dioica, los cuales fueron preparados utilizando diferentes disolventes orgánicos y obtenidos a partir de dos métodos de extracción: el extractor Soxhlet (Método I), que incluía el uso de cuatro disolventes con acetato de etilo y hexano, y las particiones secuenciales (Método II) con un sistema de cinco disolventes (butanol). Las actividades antibacterianas y antifúngicas de extractos crudos fueron ensayados contra 28 bacterias, tres cepas de levadura y siete cepas fúngicas por la difusión en disco y el método de dilución en caldo. La amoxicilina se utilizó como control positivo para cepas de bacterias, vancomicina para Streptococcus sp., nitrato de miconazol (30μg/mL) como control positivo para los hongos y levaduras, y el metanol puro (v / v) como control negativo. El ensayo de difusión en disco se utilizó para determinar la sensibilidad de las muestras, mientras que el método de dilución en caldo se utilizó para la determinación de la concentración de inhibición mínima (CIM). El acetato de etilo y el extracto de hexano del método de extracción I (AE I y EH I) mostraron mayor inhibición contra algunas bacterias patógenas tales como Bacillus cereus, MRSA y Vibrio parahaemolyticus. Una selección de extractos que mostraron algún tipo de actividad se probó para el CIM y las concentraciones mínimas bactericidas (CMB). Los valores de CIM de Bacillus subtilis y de Staphylococcus aureus resistentes a la meticilina (MRSA) usando extracto de butanol mediante el método de extracción II (EB II) fueron: 8.33 y 16.33mg/ mL, respectivamente; mientras que el valor de MIC con el uso del extracto de acetato de etilo por el Método de extracción II (EAE II) para Vibrio parahaemolyticus fue 0.13mg/mL. Nuestro estudio mostró que el 47.06% de los extractos inhibieron bacterias Gram-negativas (8 de 17), y el 63,63% de los extractos también inhibieron bacterias Gram-positivas (7 de 11), además que estadísticamente la frecuencia de la actividad antimicrobiana fue de 13.45% (35 de 342), que de este porcentaje un 21.71% pertenece alos extractos de actividad antimicrobiana con el método de extracción I (33 de 152 de los extractos crudos) y un 6.82% del método de extracción II (13 de 190 de los extractos crudos). Sin embargo, los extractos crudos del método I exhibieron una mejor actividad antimicrobiana contra las bacterias Gram-positivas que las Gram-negativas. Los resultados positivos en la detección de plantas medicinales para la actividad antibacteriana constituye información primaria para la realización de nuevos estudios fitoquímicos y farmacológicos. Por lo tanto, los extractos podrían ser adecuados como agentes antimicrobianos en la industria farmacéutica y de alimentos.