L-asparaginase is an important enzyme as therapeutic agents used in combination with other drugs in the treatment of acute lymphoblastic leukemia. A newly isolated actinomycetes strain, Streptomyces sp. NEAE-82, was potentially producing extracellular L-asparaginase, it was identified as Streptomyces fradiae NEAE-82, sequencing product was deposited in the GenBank database under accession number KJ467538. L-asparaginase was purified from the crude enzyme using ammonium sulfate precipitation, dialysis and ion exchange chromatography using DEAE Sepharose CL-6B. Further the kinetic studies of purified enzyme were carried out. The optimum pH, temperature and incubation time for maximum L-asparaginase activity were found to be 8.5, 40 °C and 30 min, respectively. The optimum substrate concentration was found to be 0.06 M. The Km and Vmax of the enzyme were 0.01007 M and 95.08 Uml−1min−1, respectively. The half-life time (T1/2) was 184.91 min at 50 °С, while being 179.53 min at 60 °С. The molecular weight of the subunits of L-asparaginase was found to be approximately 53 kDa by SDS–PAGE analysis. The purified L-asparaginase showed a final specific activity of 30.636 U/mg protein and was purified 3.338-fold. The present work for the first time reported more information in the production, purification and characterization of L-asparaginase produced by newly isolated actinomycetes Streptomyces fradiae NEAE-82.

In this study, the pink yeast Rhodotorula sp. strain ATL72 was isolated from salt marches near Mediterranean Sea, Egypt. From phylogenetic analysis, the isolated strain ATL72 was closely related to Rhodotorula bloemfonteinensis EU075187 by similarity of 40%. The biological synthesis of nanosilver (AgNPs) using the marine pink yeast Rhodotorula sp. strain ATL72 was established. The UV-Visible spectral analysis confirmed the synthesis of AgNPs showing a characteristic peak around 400-500 nm. TEM analysis not only confirmed the synthesis of AgNPs but also described the spherical and oval shaped nanoparticle besides size measurements ranged from 8.8 to 21.4 nm. The biosynthesized AgNPs showed a strong antimicrobial activity by causing a complete inhibition of growth for a wide range of Gram positive and Gram negative bacteria as well as fungi with low MIC value. In conclusion, the pink yeast Rhodotorula sp., strain ATL72 isolated from Egypt is a promising new biological source for the synthesis of silver nanoparticles having a potent antimicrobial activity against a wide range of pathogenic bacteria and fungi.

In recent years, microbial cholesterol oxidases have gained great attention due to its widespread use in medical applications for serum cholesterol determination. Streptomyces aegyptia strain NEAE-102 exhibited high level of extracellular cholesterol oxidase production using a minimum medium containing cholesterol as the sole source of carbon. Fifteen variables were screened using Plackett–Burman design for the enhanced cholesterol oxidase production. The most significant variables affecting enzyme production were further optimized by using the face-centered central composite design. The statistical optimization resulted in an overall 4.97-fold increase (15.631 UmL−1) in cholesterol oxidase production in the optimized medium as compared with the unoptimized medium before applying Plackett Burman design (3.1 UmL−1). The purified cholesterol oxidase was evaluated for its in vitro anticancer activities against five human cancer cell lines. The selectivity index values on rhabdomyosarcoma and breast cancer cell lines were 3.26 and 2.56; respectively. The in vivo anticancer activity of cholesterol oxidase was evaluated against Ehrlich solid tumor model. Compared with control mice, tumors growth was significantly inhibited in the mice injected with cholesterol oxidase alone, doxorubicin alone and cholesterol oxidase/doxorubicin combination by 60.97%, 72.99% and 97.04%; respectively. These results demonstrated that cholesterol oxidase can be used as a promising natural anticancer drug.

White rot, caused by Sclerotium cepivorum, is a serious and economically important disease of garlic, which leads to losses in the garlic production in most of the tropical, subtropical and temperate areas. Biocontrol potential of an endophytic Bacillus amyloliquefaciens GGA and/or arbuscular mycorrhizal fungi (AMF) against this disease was investigated. The B. amyloliquefaciens GGA exhibited antagonistic activity against S. cepivorum in vitro. Scanning electron microscopy revealed alterations in the morphology of the pathogen in response to the exposure to the bacterial metabolites. Results from a pot experiment demonstrated that application of the dual treatment of the B. amyloliquefaciens GGA and AMF reduced disease incidence and severity more than the single treatments, and led to the greatest increases in total phenol content, activities of the defense-related enzymes phenylalanine ammonia-lyase, polyphenoloxidase and peroxidase, and transcriptional expression levels of the defensin and chitinase genes. Growth and yield parameters of garlic plants were enhanced after this treatment. This study showed good efficacy on the tested biocontrol agents for control white rot of garlic plants grown in pots. Future research should evaluate these biocontrol strategies under field conditions.

BackgroundThere is an increasing demand on cholesterol oxidase for its various industrial and clinical applications. The current research was focused on extracellular cholesterol oxidase production under submerged fermentation by a local isolate previously identified as Streptomyces aegyptia NEAE 102. The crude enzyme extract was purified by two purification steps, protein precipitation using ammonium sulfate followed by ion exchange chromatography using DEAE Sepharose CL-6B. The kinetic parameters of purified cholesterol oxidase from Streptomyces aegyptia NEAE 102 were studied.ResultsThe best conditions for maximum cholesterol oxidase activity were found to be 105 min of incubation time, an initial pH of 7 and temperature of 37 °C. The optimum substrate concentration was found to be 0.4 mM. The higher thermal stability behavior of cholesterol oxidase was at 50 °C. Around 63.86% of the initial activity was retained by the enzyme after 20 min of incubation at 50 °C. The apparent molecular weight of the purified enzyme as sized by sodium dodecyl sulphate-polyacryalamide gel electrophoresis was approximately 46 KDa. On DEAE Sepharose CL-6B column cholesterol oxidase was purified to homogeneity with final specific activity of 16.08 U/mg protein and 3.14-fold enhancement. The amino acid analysis of the purified enzyme produced by Streptomyces aegyptia NEAE 102 illustrated that, cholesterol oxidase is composed of 361 residues with glutamic acid as the most represented amino acid with concentration of 11.49 μg/mL.ConclusionsTaking into account the extracellular production, wide pH tolerance, thermal stability and shelf life, cholesterol oxidase produced by Streptomyces aegyptia NEAE 102 suggested that the enzyme could be industrially useful.