Whole-genome Sequencing Reveals Putative Underlying Mechanisms of Biocontrol Capability of IBFCBF-5

Objective: As the world's food safety and environmental safety problems become increasingly severe, the agricultural sectors of various countries are also paying closer attention to the use of biofertilizers and biocontrol agents. Rhizosphere bacteria are a significant source of commonly used biofertilizers and biocontrol agents. This study aims to describe the genome and genomic traits of a biocontrol agent in the genus Bacillus.Results: In this paper, a strain of Bacillus amyloliquefaciens IBFCBF-5 was isolated and identified to have an inhibitory effect on several common oomycete and fungal pathogens Phytophthora capsica, Sclerotinia sclerotiorum, Colletotrichum gloeosporioides, and Fusarium oxysporum f.sp. cucumerinum. The genome of strain IBFCB-5 was sequenced, and the assembled genome was 4,338,658bp, with a G+C content of 46.05%. The IBFCBF-5 genome contains abundant GH, GT, CE, PL, AA, and CBM gene families, potentially degrading cellulose and hemicellulose, chitin, starch, xylan, peptidoglycan, etc. In addition, 14 lipopeptide and polypeptide antibiotic gene clusters were found in IBFCBF-5, including those coding for the synthesis of several known antifungal and antibacterial compounds Fengycin, Bacilysin, Bacillibactin, and plantazolicin.Conclusion: Our results show that Bacillus amyloliquefaciens IBFCBF-5 has a broad-spectrum antifungal ability and that its genome contains many genes coding for antimicrobial metabolites.

Ototoxicity of Non-aminoglycoside Antibiotics

It is well-known that aminoglycoside antibiotics can cause significant hearing loss and vestibular deficits that have been described in animal studies and in clinical reports. The purpose of this review is to summarize relevant preclinical and clinical publications that discuss the ototoxicity of non-aminoglycoside antibiotics. The major classes of antibiotics other than aminoglycosides that have been associated with hearing loss in animal studies and in patients are discussed in this report. These antibiotics include: capreomycin, a polypeptide antibiotic that has been used to treat patients with drug-resistant tuberculosis, particularly in developing nations; the macrolides, including erythromycin, azithromycin and clarithromycin; and vancomycin. These antibiotics have been associated with ototoxicity, particularly in neonates. It is critical to be aware of the ototoxic potential of these antibiotics since so much attention has been given to the ototoxicity of aminoglycoside antibiotics in the literature.

Determination of Polypeptide Antibiotic Residues in Food of Animal Origin by Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

A novel UHPLC-MS/MS method for the determination of polypeptide antibiotic residues in animal muscle, milk, and eggs was developed and validated. Bacitracin A, colistin A, colistin B, polymyxin B1, and polymyxin B2 were extracted from the samples with a mixture of acetonitrile/water/ammonia solution 25%, 80/10/10 (v/v/v), and put through further evaporation, reconstitution, and filtration steps. The chromatographic separation was performed on a C18 column in gradient elution mode. Mass spectral acquisitions were performed in selective multiple reaction monitoring mode by a triple quadrupole mass spectrometer. The method was validated according to the criteria of Commission Decision 2002/657/EC. The method quantifies polypeptides in a linear range from 10 to 1000 μg kg−1, where the lowest concentration on the calibration curve refers to the limit of quantification (LOQ). The recoveries ranged from 70 to 99%, the repeatability was below 13%, and within-laboratory reproducibility was lower than 15%. The decision limit (CCα) and detection capability (CCβ) values were calculated, and ruggedness and stability studies were performed, to fulfill the criteria for confirmatory methods. Moreover, the developed method may also be used for screening purposes by its labor efficiency.

Evaluation of colistin nephrotoxicity and urinary level of kidney injury molecule-1 in hospitalized adult ICU patients

Introduction: Colistin is a cationic polypeptide antibiotic used for treatment of gram-negative infections. Nephrotoxicity is one of the most common adverse effects of colistin. Objectives: To determine the epidemiology of colistin nephrotoxicity and also to compare the changing pattern of kidney injury molecule 1 (KIM-1) in urine with serum creatinine and urine during the treatment with colistin in patients admitted to intensive care unit (ICU). Patients and Methods: During 13 months, all patients admitted to adult ICUs of two university hospitals without any documented history of acute or chronic kidney diseases receiving at least one week of colistin were included. Required demographic, clinical, and paraclinical data of the study population was collected. Urinary and serum levels of creatinine, urea, sodium, potassium, magnesium, and KIM-1 were measured at six time points including days zero, 3, 5, 7, 10, and 14 of colistin treatment. Results: Six patients (18.18%) developed nephrotoxicity during colistin treatment. Nephrotoxicity was resolved without any intervention in three individuals. None of studied demographic, clinical and laboratory characteristics of the patients had a significant association with the incidence of colistin nephrotoxicity. The pattern of KIM-1 urine level during the course of colistin treatment did not differ significantly among patients with and without nephrotoxicity. The accuracy of KIM-1 urine level in detecting colistin nephrotoxicity was significantly lower than that of serum creatinine on days 0th, 3rd, 5th and 7th. Conclusion: Nephrotoxicity of colistin is a common complication, usually reversible, KIM-1 was not more accurate than serum creatinine or urine in detecting nephrotoxicity of colistin.

EXPRESS CONTROL OF ANTIBIOTIC BACITRICIN IN MILK: DEVELOPMENT AND TESTING OF AN IMMUNOCHROMATOGRAPHIC TEST SYSTEM

The immunochromatographic test system was developed for rapid control of polypeptide antibiotic bacitracin in milk. Its analytical parameters were determined. Visual and instrumental detection limits are 100 and 1.0 ng/ml, working range of quantitative measurements – 3–80 ng/ml, time of the assay – 10 min. The test system allows obtaining reliable information about the content of bacitracin in milk without sample preparation. The test system was validated for 90 samples of milk; good correlation with the results obtained using a commercial enzyme immunoassay kit was shown. The degree of bacitracin revealimg in milk ranged from 75 to 140%.

PHYLOGENETIC ANALYSIS OF 16S rRNA GENE FRAGMENT OF ANTIBIOTIC-PRODUCING PLS 76 ISOLATE

Exploitation of extremophiles as novel bioactive compounds sources has been increasing. The aim of this study was to evaluate the activity and the class of antibiotic produced by a thermo-halophilic isolate PLS 76, as well as to identify the genotype of the isolate. The activity was determined by a disc diffusion method, while the antibiotic class was determined qualitatively by chemical reactions using ninhydrin, iodine vapour and potassium iodine. The genotype was determined by sequencing the 16S rRNA gene fragment and the phylogenetic tree from the sequence data. The results showed that PLS 76 was a Gram-negative bacterium and able to produce polypeptide antibiotic, which showed a slight activity on E. coli and S. aureus. Sequence alignment of the 16S rRNA gene fragment showed that PLS 76 was most related to Geobacillus kaustophilus. These results may be used to utilise the isolated for further antibiotic study.

Complete Genome Sequence of Streptomyces parvulus 2297, Integrating Site-Specifically with Actinophage R4

Streptomyces parvulus 2297, which is a host for site-specific recombination according to actinophage R4, is derived from the type strain ATCC 12434. Species of S. parvulus are known as producers of polypeptide antibiotic actinomycins and have been considered for industrial applications. We herein report for the first time the complete genome sequence of S. parvulus 2297.

Autophagy Regulates Colistin-Induced Apoptosis in PC-12 Cells

ABSTRACTColistin is a cyclic cationic polypeptide antibiotic with activity against multidrug-resistant Gram-negative bacteria. Our recent study demonstrated that colistin induces apoptosis in primary chick cortex neurons and PC-12 cells. Although apoptosis and autophagy have different impacts on cell fate, there is a complex interaction between them. Autophagy plays an important role as a homeostasis regulator by removing excessive or unnecessary proteins and damaged organelles. The aim of the present study was to investigate the modulation of autophagy and apoptosis regulation in PC-12 cells in response to colistin treatment. PC-12 cells were exposed to colistin (125 to 250 μg/ml), and autophagy was detected by visualization of monodansylcadaverine (MDC)-labeled vacuoles, LC3 (microtubule-associated protein 1 light chain 3) immunofluorescence microscopic examination, and Western blotting. Apoptosis was measured by flow cytometry, Hoechst 33258 staining, and Western blotting. Autophagosomes were observed after treatment with colistin for 12 h, and the levels of LC3-II gene expression were determined; observation and protein levels both indicated that colistin induced a high level of autophagy. Colistin treatment also led to apoptosis in PC-12 cells, and the level of caspase-3 expression increased over the 24-h period. Pretreatment of cells with 3-methyladenine (3-MA) increased colistin toxicity in PC-12 cells remarkably. However, rapamycin treatment significantly increased the expression levels of LC3-II and beclin 1 and decreased the rate of apoptosis of PC-12 cells. Our results demonstrate that colistin induced autophagy and apoptosis in PC-12 cells and that the latter was affected by the regulation of autophagy. It is very likely that autophagy plays a protective role in the reduction of colistin-induced cytotoxicity in neurons.