Antagonist activities and phylogenetic relationships of actinomycetes isolated from an Artemisia habitat / Actividades antagónicas y relaciones filogenéticas de actinomicetos aislados de un hábitat de Artemisia

Abstract Diverse habitats have been screened for novel antimicrobial actinomycetes, while others remain unexplored. In this study, we analyzed the bioactivities of actinomycetes cul-tured from rhizosphere soils of the desert plant Artemisia tridentata and the nearby bulk soils. Actinomycetes were screened for antifungal and antibacterial activities toward a panel of plant pathogens; all comparisons were between activities of rhizosphere soil isolates toward those of its counterpart bulk soil. A selected group of the strongest antifungal isolates were also tested against two antifungal-drug resistant strains of Candida albicans. 16S rDNA partial sequences and phylogenetic analysis of isolates that showed broad-spectrum antifungal activities were performed. Forty-two out of 200 and two soil isolated actinomycetes were selected for their strong antifungal activities. The highest proportion of isolates (p <0.05) from rhizosphere soil of an old plant showed antagonism against gram-positive bacteria (0.483 and 0.224 propor-tions against Bacillus subtilis and Rathayibacter tritici, respectively), and phytopathogenic fungi (0.259, 0.431, and 0.345 proportions against Fusarium oxysporum, Rhizoctonia solani and Pythium ultimum, respectively), while the highest antagonism against the gram-negative bacteria predominated in isolates from the bulk soils. Isolates from a rhizosphere soil of a young plant were characterized for strong antagonist activities against Fusarium oxysporum (0.333 proportion, p<0.05). Phylogenetic analysis of 16S rDNA sequences showed that isolates that exhibited strong antifungal activity were genetically similar. We conclude that the rhizosphere soil of A. tridentata is an excellent source for discovery of actinomycetes with potentially novel antifungal compounds.

Resumen En la búsqueda de actinomicetos antimicrobianos se han estudiado diversos hábitats, pero muchos permanecen aún sin explorar. En este estudio analizamos las actividades biológicas de cultivos de actinomicetos provenientes de suelos rizosféricos de la planta desértica Artemisia tridentata y de suelos no asociados a sus raíces. Los actinomicetos fueron seleccionados por sus actividades antifúngicas y antibacterianas contra un panel de patógenos de plantas. Todas las comparaciones fueron entre las actividades de los aislados rizosféricos y aquellas de los aislados no asociados a las raíces. Un grupo selecto de los aislados con las mayores actividades antifúngicas fueron también evaluados contra 2 cepas de Candida albicans resistentes a antifúngicos. Se realizó la secuenciación parcial del ARNr 16S y el análisis filogenético de los aislados que mostraron actividades antifúngicas de amplio espectro. Se seleccionaron 42 de 202 actinomicetos aislados por sus fuertes actividades antifúngicas. La mayor proporción de aislados de suelo rizosférico de plantas viejas mostraron antagonismo contra bacterias gram positivas y hongos fitopatógenos (proporciones de 0,259; 0,431 y 0,345 contra Fusarium oxyspo-rum, Rhizoctonia solani y Pythium ultimum, respectivamente), mientras que la mayor actividad antagónica contra las bacterias gram negativas predominaron en aislados de suelo no asociado a raíces. Los aislados de suelo rizosférico de plantas jóvenes se caracterizaron por una fuerte actividad antagónica contra F. oxysporum (proporción de 0,333, p < 0,05). El análisis filogenético de secuencias del ADNr 16S mostró que los aislados que presentaron fuerte actividad antifúng-ica fueron genéticamente similares. Concluimos que el suelo rizosférico de A. tridentata es una fuente excelente para el descubrimiento de actinomicetos productores de compuestos antifúngicos potencialmente novedosos.

In vitro anti-Candida activity of Melaleuca cajuputi extracts

Aims@#The rise of drug-resistant infectious diseases worldwide has spurred experts' interest in developing safe and effective alternative medicine. Melaleuca cajuputi extracts have been shown to exhibit antimicrobial activity in vitro against various bacterial species. This study evaluated the antimicrobial activity of local M. cajuputi leaf extracts (MCEs) against Candida albicans.@*Methodology and results@#Phytoconstituents of aqueous and ethanolic MCEs were screened conventionally using chemical tests. Broth microdilution assay and scanning electron microscope (SEM) were performed to study the anti-Candida activity of the extracts. Both MCEs contained terpenoids, phenols, flavonoids and tannins. Aqueous and ethanolic MCEs showed good fungicidal activity against the tested organism with minimum inhibitory concentration (MIC) values of 50 mg/mL and 25 mg/mL, respectively and a minimum fungicidal concentration (MFC) to MIC ratio of less or equal to 2. Scanning electron micrographs revealed yeast cell surface morphology alterations when treated with both MCEs at 1× MIC.@*Conclusion, significance and impact of study@#In conclusion, MCEs have anti-Candida properties and thus, M. cajuputi extract could be an excellent potential source of natural antimicrobial agents for disease remedies.

In vitro anti-Candida activity of Quercus infectoria gall extract-based vaginal cream and its local tissue effects in vivo

Aims@#Aqueous extract of Quercus infectoria (QI) galls has been reported to possess anti-fungal and anti-inflammatory activities. Hence, this study aimed to determine in vitro antimicrobial activity of formulated QI gall extract-based vaginal cream against Candida albicans and to evaluate the possible side effects on the cervicovaginal epithelium of healthy rats. @*Methodology and results@#Three different cream formulations containing 10%, 20%, and 30% of QI gall extract respectively were tested for their antimicrobial activity against C. albicans (ATCC 10231) by using disc diffusion test. Microbroth serial dilution method was performed in determining the minimum inhibitory concentration (MIC) and fungicidal concentration (MFC). The 30% formulated extract cream (FEC) was applied topically on the cervicovaginal surface of healthy Sprague Dawley (SD) rats and examined for local tissue effects histologically. The mean scores of inhibition zone diameter were compared by one-way ANOVA and post-hoc test using PRISM software. All extract cream formulations displayed a relatively good anti-Candida activity. The MIC values exhibited by 10%, 20%, and 30% FEC against C. albicans were 1.094 mg/mL, 0.547 mg/mL, and 0.068 mg/mL, respectively. The 10% and 20% FECs showed a significant difference (P=0.0254) in the mean of inhibition zone diameter. The lowest MFC value (0.068 mg/mL) was shown by 30% FEC. There were no abnormal changes seen at the vagina and cervical mucosa after 2 weeks application of 30% FEC. @*Conclusion, significance and impact of study@#QI gall extract formulated in the cream base has an anti-Candida activity in vitro and the present finding suggests that this herbal cream formulation is potentially useful in preventing vaginal candidiasis without causing any unwanted local side effects.

Influence of glucose and stirring in the fermentation process in order to produce anti-Candida metabolites produced by Streptomyces sp

ABSTRACT This study evaluated the influence of glucose and stirring in the fermentation process in order to produce anti-Candida metabolites produced by Streptomyces sp. MPO4 isolated from Amazon soil. The anti-Candida metabolites production was registered after 24 h of fermentation in stirred ISP2 medium, having antifungal inhibition halos between 12.3 mm and 25.3 mm, yielding higher production of anti-Candida agents after 96 h. Stirring was a determining factor for the production of anti-Candida secondary metabolites, since the absence of glucose reflected in the late production of the antifungal starting from Streptomyces sp.

RESUMO Este estudo avaliou a influência da glicose e agitação no processo de fermentação para a produção de metabólitos anti-Candida produzidos por Streptomyces sp. MPO4 isolado do solo da Amazônia. A produção dos metabólitos anti-Candida foi registrada a partir de 24 h de fermentação sob agitação em meio ISP2, apresentando halos de inibição entre 12,3 mm e 25,3 mm, obtendo-se maior produção do antifúngico em 96 h. A agitação foi um fator determinante para a produção de metabólitos secundários anti-Candida e a ausência de glicose refletiu na produção tardia do antifúngico a partir do Streptomyces sp.

Susceptibility characterisation of Candida spp. to four essential oils.

In the present investigation, anti-Candida activity of four essential oils i.e. Black cumin (Nigella sativa), Curry leaf (Murraya koienigii), Ajwain (Trachiyspirum ammi), and Betel leaf (Piper betel) were screened against four human pathogenic species of Candida viz. Candida albicans, Candida tropicalis, Candida glabrata, and Candida parapsilosis. The minimum inhibitory concentration (MIC) values of the oils ranged between 15.62 and 250 l/ml while studied through tube dilution method. The oils retained their anti-Candida activities even after heat treatment (at 45ºC, 60ºC, 100ºC for 1 hour) and also on autoclaving. Both Ajwain and Black Cumin leaf oils showed better anti-Candida activity against Candida albicans, resulting in an irreversible damage to the cells. The anti-Candida activity of these essential oils could be attributable to the membrane inhibition mechanism. The activity of the oils is reported to be microbicidal (Candida-cidal).