Isolation, purification and properties of lipase from Pseudomonas aeruginosa

Six isolates (Ps1, Ps2, Ps3, Ps4, Ps5 and Ps6) producing lipase were screened from wastewater on a selective medium agar containing Tween 80 or olive oil as the only source of carbon. Isolate Ps5 showed the highest lipase activity which was later identified as Pseudomonas aeruginosa. The effect of media composition was analysed to maximize the production of lipase. The maximum extracellular lipase present in the broth was purified 4 folds with an overall yield of 19.4% through the purification procedure of ammonium sulphate precipitation and diethyl aminoethyl (DEAE) cellulose chromatography. The purified lipase had the maximal activity within the pH range of 6 to 8, with an optimum pH of 7, and within the temperature range of 20 to 35°C, with an optimum temperature for the hydrolysis of olive oil at 30°C. The enzyme activity of P. aeruginosa lipase was enhanced by Ca 2+ and Mg2+ but strongly inhibited by heavy metals such as Zn2+, Cu2+and Mn2+.Key words: Pseudomonas, lipase, purification, biomass, heavy metals

Biochemische Charakterisierung der Ribonucleotid-Reduktase aus Corynebacterium glutamicum im Vergleich zum Manganenzym aus Corynebacterium ammoniagenes

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ETUDE DE L’EFFICACITE DE L’EXTRAIT ETHANOLIQUE D’ECORCES DE PUNICA GRANATUM LINN SUR DEUX SOUCHES PHYTOPATHOGENES :ASCOCYHTA RABIEI (PASS.) LABR. ET FUSARIUM OXYSPORUM F.SP.RADICIS –LYCOPERSICI

The aim of this study is the evaluation of the antifungal activity ofPunica granatum peel towartds two phytopathogenic agents, wich are: theAscocyhta rabiei (pass .) Labr and Fusarium oxysporum f.sp . radicislycopersici(FORL). To test the effectiveness of the ethanol extract ofpomegranate peel (EEPP), three parameters were studied: the mycelialgrowth, inhibition rate and sporulation. It is thus that the strain of Fusariumoxysporum lycopersici f.sp.Radicis was more resistant to 5% EEPP withmycelial growth of 9 mm and an inhibition rate of 75.67%, compared tothose of Ascocyhta rabiei (pass). Labr with mycelial growth of 7 mm andan inhibition rate of 79.41% after 7 days of incubation. This difference ismainly due to the sensitivity and the natural resistance of the strains tested

ÉVALUATION DE L’EFFET INHIBITEUR DES HUILES ESSENTIELLES DE LAVANDULA LATIFOLIA VIS-À-VIS DE CORYNEBACTERIUM AMMONIAGENES ATCC 6872 ET DE SON MUTANT CH31.

The abusive use of antibiotics in human and veterinary medicine create a selective pressure on bacterial populations, This produces the emergence of multi-resistant bacterial strains leading to treatment failures and an additional cost anti-infective treatments. These findings call for finding other alternative treatments. The aim of this study is the evaluation of the antibacterial properties of the essential oils of the leaves of Lavandula latifolia harvested from Sidi Bel Abbes region (Algeria), which were evaluated against Corynebacterium ammoniagenes ATCC 6872 and its CH31 mutant, by the using agar well diffusion method and by the study of bacterial growth in the absence and the presence of essential oils. The obtained results showed that the antibacterial activity of the essential oils of the leaves of Lavandula latifolia at various concentrations has indicated an excellent antibacterial activity by Corynebacterium ammoniagenes ATCC 6872 and its CH31 mutant, with a average values of I50 = 0.06 mM et I50= 0.1 mM respectively. Furthermore, the study of CH31 mutant growth in the absence (control) and in the presence of the essential oils of the leaves of Lavandula latifolia has manifested a considerable biomass reduction accompanied with unbalanced growth after adding of the crude extract

ÉVALUATION DE L’EFFET INHIBITEUR DES HUILES ESSENTIELLES DE LAVANDULA LATIFOLIA VIS-À-VIS DE CORYNEBACTERIUM AMMONIAGENES ATCC 6872 ET DE SON MUTANT CH31.

The abusive use of antibiotics in human and veterinary medicine create a selective pressure on bacterial populations, This produces the emergence of multi-resistant bacterial strains leading to treatment failures and an additional cost anti-infective treatments. These findings call for finding other alternative treatments. The aim of this study is the evaluation of the antibacterial properties of the essential oils of the leaves of Lavandula latifolia harvested from Sidi Bel Abbes region (Algeria), which were evaluated against Corynebacterium ammoniagenes ATCC 6872 and its CH31 mutant, by the using agar well diffusion method and by the study of bacterial growth in the absence and the presence of essential oils. The obtained results showed that the antibacterial activity of the essential oils of the leaves of Lavandula latifolia at various concentrations has indicated an excellent antibacterial activity by Corynebacterium ammoniagenes ATCC 6872 and its CH31 mutant, with a average values of I50 = 0.06 mM et I50= 0.1 mM respectively. Furthermore, the study of CH31 mutant growth in the absence (control) and in the presence of the essential oils of the leaves of Lavandula latifolia has manifested a considerable biomass reduction accompanied with unbalanced growth after adding of the crude extract

Metallation and mismetallation of iron and manganese proteins in vitro and in vivo: the class I ribonucleotide reductases as a case study

How cells ensure correct metallation of a given protein and whether a degree of promiscuity in metal binding has evolved are largely unanswered questions. In a classic case, iron- and manganese-dependent superoxide dismutases (SODs) catalyze the disproportionation of superoxide using highly similar protein scaffolds and nearly identical active sites. However, most of these enzymes are active with only one metal, although both metals can bind in vitro and in vivo. Iron(II) and manganese(II) bind weakly to most proteins and possess similar coordination preferences. Their distinct redox properties suggest that they are unlikely to be interchangeable in biological systems except when they function in Lewis acid catalytic roles, yet recent work suggests this is not always the case. This review summarizes the diversity of ways in which iron and manganese are substituted in similar or identical protein frameworks. As models, we discuss (1) enzymes, such as epimerases, thought to use Fe[superscript II] as a Lewis acid under normal growth conditions but which switch to Mn[superscript II] under oxidative stress; (2) extradiol dioxygenases, which have been found to use both Fe[superscript II] and Mn[superscript II], the redox role of which in catalysis remains to be elucidated; (3) SODs, which use redox chemistry and are generally metal-specific; and (4) the class I ribonucleotide reductases (RNRs), which have evolved unique biosynthetic pathways to control metallation. The primary focus is the class Ib RNRs, which can catalyze formation of a stable radical on a tyrosine residue in their β2 subunits using either a di-iron or a recently characterized dimanganese cofactor. The physiological roles of enzymes that can switch between iron and manganese cofactors are discussed, as are insights obtained from the studies of many groups regarding iron and manganese homeostasis and the divergent and convergent strategies organisms use for control of protein metallation. We propose that, in many of the systems discussed, “discrimination” between metals is not performed by the protein itself, but it is instead determined by the environment in which the protein is expressed.National Institutes of Health (U.S.) (Grant GM81393

Microencapsulation of LL-37 Antimicrobial Peptide in PLGA

Antimicrobial peptides are key actors in organismsÂ’ immune systems. They play an important role in phagocytosis, breaking bacteria membranes. They destroy the microbes, keeping them from repairing themselves, and therefore do not promote antimicrobial resistance. LL37 is a peptide produced by the human body. It is a short amino acid chain that is particularly active on the skin and mucous membranes. It has antimicrobial and fungal activity as well as wound healing properties, which makes it a very interesting active substance in wound treatment. However, its fragile and sensitive structure is a challenge to its use. Nowadays, encapsulation in a biocompatible polymer system is a promising technique in drug delivery, and presents a solution to LL37 administration and delivery. LL37 is a hydrophilic active substance, it will be trapped in PLGA (poly (lactic-co-glycolic acid)) by double emulsion and the microspheres will be shaped and stabilized by solvent evaporation. The capsules will be characterized by Dynamic Light Scattering (DLS) and Scanning Electron Microscopy. Their main features, drug loading, encapsulation efficiency and release profile, are determined using the Bradford assay. Since the peptide is expensive and delicate, it is important to optimize its encapsulation. For that reason, we will adapt the process to have the best drug loading as possible using water in oil in oil emulsions. For an external use, the capsules would be used over a few days, so having a fast release is very relevant. The larger the specific surface area, the faster the diffusion. For that reason, we will also study the impact of porosity on the release profile. As a result, different types of capsules will be synthesized, with higher porosity and by two processes: aqueous double emulsion and oil double emulsion. Their characteristic features and impact on bacterial pathogens will be determined and compared in order to determine their optimal synthesis process and formulation in given conditions of use

Characterization of Fluorescent Rhizobacteria Isolated From Oleander (Nerium oleander L.) and Olivier (Olea oleaster L.) With Antagonistic Effect Against Fusarium oxysporum f. sp. radicis-lycopersici

This study aims to characterize the biocontrol potential of two fluorescent rhizobacteria isolated from Oleander (Nerium oleander L.) and Olivier (Olea oleaster L.). The isolation was done in Cetrimide agar. The fluorescing strains at 366 nm were selected for the dual plate assay against the tomato pathogen Fusarium oxysporum f.sp. radicis-lycopersici. The two best strains showing the highest inhibition rates (Pa2 and S2Pf1 with 31.36% and 51.42% respectively) were chosen to be identified and characterized for their production of antifungal molecules. The taxonomical determination based on macro and micromorphological observations in addition to the biochemical tests of the API 20E and API 20NE strips analyzed by the heuristic soft "PIBwin 2.0.0" suggests the strain Pa2 as a Pseudomonas aeruginosa while the strain S2Pf1 belongs to the Burkholderia cepacia species. The antifungal potential was assessed through the quantification/detection of the following bioactive molecules: salicylic acid, hydrogen cyanide, rhamnolipids, chitinases, and cellulases. The strain Burkholderia cepacia S2Pf1 showed a better antifungal profile in comparison to Pseudomonas aeruginosa Pa2. The determination of the growth kinetics parameters of Burkholderia cepacia S2Pf1 based on observed OD600 data, DModel data fitting, and Gompertz model data fitting highlighted a relatively good ability to quickly reach high bacterial densities in both nutrient and seed broths. Thus, Burkoledria cepacia S2Pf1 is suggested as a good candidate to be further assessed for its biocontrol proprieties against Fusarium oxysporum f.sp. radicis-lycopersici

Making DNA without iron: induction of a manganese-dependent ribonucleotide reductase in response to iron starvation

Ribonucleotide reductases supply cells with their deoxyribonucleotides. Three enzyme types are known, classes I, II and III. Class II enzymes are anaerobic whereas class I enzymes are aerobic, and so class I and II enzymes are often produced by the same organism under opposing oxygen regimes. Escherichia coli contains two types of class I enzyme (Ia and Ib) with the Fe-dependent Ia enzyme (NrdAB) performing the major role aerobically, leaving the purpose of the Ib enzyme (NrdEF) unclear. Several papers have recently focused on the class Ib enzymes showing that they are Mn (rather than Fe) dependent and suggesting that the E. coli NrdEF may function under redox-stress conditions. A paper published in this issue of Molecular Microbiology from James Imlay's group confirms that this unexplained NrdEF Ib enzyme is Mn-dependent, but shows that it does not substitute for NrdAB during redox stress. Instead, a role during iron restriction is demonstrated. Thus, the purpose of NrdEF (and possibly other class Ib enzymes) is to enhance growth under aerobic, low-iron conditions, and to functionally replace the Fe-dependent NrdAB when iron is unavailable. This finding reveals a new mechanism by which bacteria adjust to life under iron deprivation