Diversity and Antimicrobial Activity of Actinomycetes Isolated from Lut Desert: The Extremely Arid Climatic Zones of Iran

Lut desert is situated in one of the extremely arid climatic zones of Iran and is one of the hottest deserts in our plant with the extreme fluctuation of temperature over a day. The main objective of this study is to characterize the diversity of the culturable actinomycetes and preliminary evaluation of their extracts as antimicrobial components on drug resistant pathogens. Twenty-four soil samples were collected, successively diluted and inoculated into the different culture media to support the growth of most culturable bacteria including actinomycetes. Phenotypic and molecular methods were used for accurate identification of recovered isolates particularly actinomycetes at the genus and species levels. The isolates were also evaluated for their inhibitory activities against drug resistant Acinetobacter baumannii, Enterococcus faecium, Klebsiella pneumoniae and Staphylococcus aureus. A total of 56 isolates recovered from the samples. Based on phenotypic tests, 41 isolates were identified as actinomycetes, amongst them 8 isolates were active against drug resistant pathogens. Our study revealed Lut desert, as one of the hottest deserts in the world, is the habitat to diverse taxa of bacteria particularly actinomycetes which have potential novel antimicrobial components.

     

Genetic diversity of Iranian clinical isolates of Mycobacterium tuberculosis

In the current study we aimed to execute a rather less complicated molecular tying method, i.e. the random amplification of polymorphic DNA (RAPD) analysis to find the heterogeneity of Iranian strains of Mycobacterium tuberculosis. The isolates comprised a total of 96 strains of M. tuberculosis collected from clinical specimens of patients in Isfahan and Tehran. The isolates were assigned to the species M. tuberculosis by the key conventional and molecular methods. They were then subjected to RAPD analysis by four arbitrary primers, namely, the primers 27F, 1525R, MS- GF and INS-2. They were then evaluated for the number and intensity of the band patterns. The RAPD profiles of the Iranian isolates showed a degree of heterogeneity which varied based on the primer used. However, analysis of the isolates by primer INS-2 revealed the highest degree of diversity yielding 31 distinguishable RAPD types. RAPD analysis provides a rapid and easy means of identifying heterogeneity among the M. tuberculosis isolates. This typing system might be considered a valuable alternative molecular typing for countries with limited resources provided that the reproducibility and reliability of the method is carefully assured.     

Effects of dietary Ergosan on cutaneous mucosal immune response in rainbow trout (Oncorhynchus mykiss)

The effects of dietary Ergosan on the growth performance and mucosal immunity in rainbow trout skin were investigated. 60 rainbow trout (100-110 g) were randomly assigned to 2 groups in triplicates and fed one of the experimental diet formulated with 5 g kg⁻¹ Ergosan or control diet for 50 days. Results showed that on the 45th day of feeding trial, Ergosan supplementation significantly enhanced the growth performance compared to control group. Various enzyme activities, namely lysozyme, protease, alkaline phosphatase and esterase in treatment group were also enhanced on the 45th and 50th day. Skin mucus in Ergosan-fed fish showed the agglutination of erythrocytes while in control group, no visible agglutination was shown. In addition, skin mucus in treatment group showed strong antibacterial activity against Yersinia ruckeri. In conclusion, the major immune components of rainbow trout mucus that are involved in the non-specific immunity were enhanced by administration of Ergosan in 5 g kg⁻¹.     

Hilyses®, fermented Saccharomyces cerevisiae, enhances the growth performance and skin non-specific immune parameters in rainbow trout (Oncorhynchus mykiss)

Effects of Hilyses^®, fermented Saccharomyces cerevisiae (S. cerevisiae), on growth, body composition and skin mucus immune components in rainbow trout were quantified. Ninety rainbow trout (105 ± 5 g) were randomly assigned to 2 groups in triplicates and fed dietary Hilyses^® (5 g kg^?1) or control diet without Hilyses^® for 50 days. Results of this study demonstrated that growth performance increased significantly by the dietary yeast supplement; however body composition was not affected in treatment group. At the 45th and 50th day of feeding trial, results of mucus samples demonstrated that yeast supplementation in treatment group significantly promoted enzyme activities, namely lysozyme, protease, alkaline phosphatase and esterase compared to control group. Significant increases were also observed in hemagglutination and antibacterial activity against Yersinia ruckeri in fish fed treatment diet. The present study suggests that fermented S. cerevisiae may effectively promote the growth performance and skin non-specific immune parameters in rainbow trout.     

Genus Pseudonocardia: What we know about its biological properties,abilities and current application in biotechnology

The genus Pseudonocardia belongs to a group of Actinomycetes, and is a member of the family Pseudonocardiacea. The members of this genus are aerobic, Gram-positive, non-motile bacteria that are commonly found in soil, plant and environment. Although this genus has a low clinical significance; however, it has an important role in biotechnology due to the production of secondary metabolites, some of which have anti-bacterial, anti-fungal and anti-tumour effects. The use of phenotypic tests, such as gelatinase activity, starch hydrolysis, catalase and oxidase tests, as well as molecular methods, such as polymerase chain reaction, are necessary for Pseudonocardia identification at the genus and species levels.