Saccharothrix sp. PAL54, a new chloramphenicol-producing strain isolated from a Saharan soil

An actinomycete strain designated PAL54, producing an antibacterial substance, was isolated from a Saharan soil in Ghardaïa, Algeria. Morphological and chemical studies indicated that this strain belonged to the genus Saccharothrix. Analysis of the 16S rDNA sequence showed a similarity level ranging between 96.9 and 99.2% within Saccharothrix species, with S. longispora DSM 43749T, the most closely related. DNA–DNA hybridization confirmed that strain PAL54 belonged to Saccharothrix longispora. It showed very strong activity against pathogenic Gram-positive and Gram-negative bacteria responsible for nosocomial infections and resistant to multiple antibiotics. Strain PAL54 secreted the antibiotic optimally during mid-stationary and decline phases of growth. One antibacterial compound was isolated from the culture broth and purified by HPLC. The active compound was elucidated by uv-visible and NMR spectroscopy and by mass spectrometry. The results showed that this compound was a D(-)-threo chloramphenicol. This is the first report of chloramphenicol production by a Saccharothrix species

In vitro antimicrobial potential of organic solvent extracts of novel actinomycetes isolated from forest soil

In vitro screening of antibacterial and antifungal activities of hexane, chloroform, ethyl acetate, methanol and water extracts of selected promising actinomycetes strains were studied towards Gram-positive, Gram-negative bacteria, dermatophytes and opportunistic pathogens. Crude antimicrobial metabolites were extracted by liquid-liquid extraction and solid-liquid extraction method using hexane, chloroform, ethyl acetate and methanol. The lowest minimum inhibitory concentration (MIC) of the extracts was assessed by the broth micro dilution method. All the extracts obtained from eight strains showed promising activity against tested Gram-positive bacteria. The hexane extracts of strain ERI-1 exhibited activity against Bacillus subtilis, Staphylococcus aureus and Staphylococcus epidermidis at a concentration of 5 mg/ml. Ethyl acetate extract of strain ERI-4 showed MIC of 5 mg/ml but S. epidermidis and S. aureus. B. subtilis exhibited activity at 2.5 mg/ml. However, ethyl acetate and lyophilized water extract of strain ERI-3 inhibited the growth of Trichophyton mentagrophytes, Trichophyton rubrum, Epidermophyton floccosum and Scropulariopsis sp at 10 mg/ml. Overall significant antibacterial and antifungal activities were noted in the ethyl acetate extract of ERI-1 and ERI-3. Methanol extract of ERI-26 exhibited good antibacterial and antifungal activities.Keywords: Actinomycetes, organic extracts, minimum inhibitory concentration (MIC), antimicrobial activityAfrican Journal of Biotechnology, Vol 13(18), 1891-189

Neem leaves mediated preparation of NiO nanoparticles and its magnetization, coercivity and antibacterial analysis

Nickel oxides nanoparticles (NiO NPs) were synthesized by biosynthesis method with the help of phytoconstituents present in the neem leaf. Further the synthesized NiO NPs were subjected for structural, optical, morphological and magnetic properties. The XRD patterns clearly infer the presence of polycrystalline nature of samples (0 1 0), (0 1 1) and (0 1 2) with hexagonal crystal phase. Morphological studies using Transmission Electron Microscope (TEM) reveals that the biosynthesized NiO NPs were in shape of oblong with 12 nm in size. Elemental analysis (EDAX) confirms the quantity of Ni is present at 51% and remaining O as 49% as well as the mass magnetization values of 61 emu/g are also recorded for NiO NPs and its coercivity values in the range of 0.2–0.4 of nanoparticles respectively. Finally the NiO NPs was studied for bacterial activity against Staphylococcus aureus (MTCC 1430) and followed by Escherichia coli (MTCC 739) by agar diffusion assay. Keywords: Neem seed, NiO NPs, Coercivity, Magnetic properties, Bacterial activitie

Mechanochemical synthesis of chitosan submicron particles from the gladius of Todarodes pacificus

The present work focused on the synthesis of β-chitosan submicron particles (CSPs) from Todarodes pacificus using mechanochemical techniques. The gladius was submitted to a sequence of mechanical and chemical treatments to synthesize β-chitin (CT), which was further deacetylated to form spherical chitosan submicron particles with an average diameter of ⩽100 nm. The surface morphology of β-chitin and CSPs was observed using electron microscopy. The degree of deacetylation (DD%), evaluated from the absorbance peak of a Fourier Transform Infrared (FTIR) spectrum, was 80 ± 2.5%. Physicochemical characterization exhibited good crystallinity, positive zeta potential and low molecular weight, as well as reduced ash content and high water-binding capacity. CSPs exhibit significant antimicrobial properties toward all tested pathogenic bacterial and fungal microorganisms. Antioxidant analysis revealed high reducing power and excellent scavenging and chelating ability. Hence, CSPs synthesized from gladius of Todarodes pacificus using mechanochemical techniques are promising candidates for biomedical applications

Influence of Indole-3-Acetic Acid and Gibberellic Acid on Phenylpropanoid Accumulation in Common Buckwheat (Fagopyrum esculentum Moench) Sprouts

We investigated the effects of natural plant hormones, indole-3-acetic (IAA) acid and gibberellic acid (GA), on the growth parameters and production of flavonoids and other phenolic compounds in common buckwheat sprouts. A total of 17 phenolic compounds were identified using liquid chromatography-mass spectrometry (LC-MS) analysis. Among these, seven compounds (4-hydroxybenzoic acid, catechin, chlorogenic acid, caffeic acid, epicatechin, rutin, and quercetin) were quantified by high-performance liquid chromatography (HPLC) after treating the common buckwheat sprouts with different concentrations of the hormones IAA and GA. At a concentration of 0.5 mg/L, both IAA and GA exhibited the highest levels of growth parameters (shoot length, root length, and fresh weight). The HPLC analysis showed that the treatment of sprouts with IAA at concentrations ranging from 0.1 to 1.0 mg/L produced higher or comparable levels of the total phenolic compounds than the control sprout and enhanced the production of rutin. Similarly, the supplementation with 0.1 and 0.5 mg/L GA increased the content of rutin in buckwheat sprouts. Our results suggested that the treatment with optimal concentrations of IAA and GA enhanced the growth parameters and accumulation of flavonoids and other phenolic compounds in buckwheat sprouts