Antibiotics produced by Streptomyces

Streptomyces is a genus of Gram-positive bacteria that grows in various environments, and its shape resembles filamentous fungi. The morphological differentiation of Streptomyces involves the formation of a layer of hyphae that can differentiate into a chain of spores. The most interesting property of Streptomyces is the ability to produce bioactive secondary metabolites, such as antifungals, antivirals, antitumorals, anti-hypertensives, immunosuppressants, and especially antibiotics. The production of most antibiotics is species specific, and these secondary metabolites are important for Streptomyces species in order to compete with other microorganisms that come in contact, even within the same genre. Despite the success of the discovery of antibiotics, and advances in the techniques of their production, infectious diseases still remain the second leading cause of death worldwide, and bacterial infections cause approximately 17 million deaths annually, affecting mainly children and the elderly. Self-medication and overuse of antibiotics is another important factor that contributes to resistance, reducing the lifetime of the antibiotic, thus causing the constant need for research and development of new antibiotics.

Antibiotics produced by Streptomyces.

Streptomyces is a genus of Gram-positive bacteria that grows in various environments, and its shape resembles filamentous fungi. The morphological differentiation of Streptomyces involves the formation of a layer of hyphae that can differentiate into a chain of spores. The most interesting property of Streptomyces is the ability to produce bioactive secondary metabolites, such as antifungals, antivirals, antitumorals, anti-hypertensives, immunosuppressants, and especially antibiotics. The production of most antibiotics is species specific, and these secondary metabolites are important for Streptomyces species in order to compete with other microorganisms that come in contact, even within the same genre. Despite the success of the discovery of antibiotics, and advances in the techniques of their production, infectious diseases still remain the second leading cause of death worldwide, and bacterial infections cause approximately 17 million deaths annually, affecting mainly children and the elderly. Self-medication and overuse of antibiotics is another important factor that contributes to resistance, reducing the lifetime of the antibiotic, thus causing the constant need for research and development of new antibiotics.

Ocorrência do fungo entomopatogênico Isaria javanica (Frieder. & Bally) Samson & Hywell-Jones (Fungi, Sordariomycetes) em lagartas de Lonomia obliqua Walker (Lepidoptera, Saturniidae, Hemileucinae) / Occurrence of the entomopathogenic fungus Isaria javanica (Frieder. & Bally) Samson & Hywell-Jones (Fungi, Sordariomycetes) infecting Lonomia obliqua Walker (Lepidoptera, Saturniidae, Hemileucinae) caterpillars

Este fungo foi isolado pela primeira vez de lagartas de L. obliqua de uma agregação em plátano (Platanus acerifolia (Aiton) Wild - Platanaceae), em Bento Gonçalves, RS, Brasil. Após isolamento, purificação e caracterização, realizou-se um teste de patogenicidade com lagartas sadias de L. obliqua para corroborar, sua infectividade pelo postulado de Koch. Constatou-se correspondência morfológica e molecular entre o inóculo e o reisolado, comprovando sua patogenicidade a L. obliqua.

It is recorded for the first time the occurrence of the entomopathogenic fungus Isaria javanica (Frieder. & Bally) Samson & Hywell-Jones (Fungi: Sordariomycetes) infecting Lonomia obliqua Walker (Lepidoptera: Saturniidae: Hemileucinae) caterpillars. This fungus was isolated from L. obliqua individuals collected from Platanus acerifolia (Aiton) Wild- Platanaceae in Rio Grande do Sul state, Brazil. After isolation, purification and characterization, fungal conidia were inoculated on healthy L. obliqua caterpillars and from dead caterpillars the fungal isolates were again obtained. New isolates and the original isolate did not differ when compared by morphological and molecular tests.

PCR method for the detection of potential ochratoxin-producing Aspergillus species in coffee beans.

Ochratoxin A (OA) is a nephrotoxic and carcinogenic mycotoxin that has been found in cereal and food commodities. Currently, Aspergillus carbonarius, A. niger and A. ochraceus have been recognized as the species responsible for OA in coffee beans. With the aim of developing multiplex-PCR for detection of these species in coffee bean samples, we first developed specific primers for A. niger detection. The primer designed (OPX7(372)) provided an amplicon of 372 pb in all A. niger stricto sensu isolates. The PCR assay developed for A. niger identification in pure culture was also successfully used for detecting this species in coffee beans. No cross-reaction was observed using DNA from coffee beans inoculated with closely related black aspergilli species. A multiplex-PCR method for detection of A. carbonarius, A. niger and A. ochraceus species in coffee beans was developed. From a single assay this method detected the amplicons of 809, 372, and 260 pb that represent the three most ochratoxigenic species found in coffee bean samples, i.e., A. carbonarius, A. niger and A. ochraceus, respectively.