Hesham Ali El-Enshasy

Optimization of the cultivation medium for natamycin production by Streptomyces natalensis

The effects of certain nutrients on natamycin production by Streptomyces natalensis in submerged batch culture were studied. The production of this antibiotic required glucose in the cultivation medium with a concentration of 20 g/l. On the other hand, the highest antibiotic production was obtained in a cultivation medium containing 0.05 g/l of potassium dihydrogen phosphate. Further increase in phosphate concentration resulted in a significant increase in biomass concomitant with lower antibiotic production. Among different N‐sources tested, only ammonium sulphate, sodium nitrate and beef extract were the suitable nitrogen sources in supporting the antibiotic production. Furthermore, a mixture of beef extract and yeast extract (8 g/l and 2 g/l, respectively) exhibited a synergistic effect in enhancing the natamycin production reaching about 1.5 g/l.

Influence of inoculum type and cultivation conditions on natamycin production by Streptomyces natalensis

This study demonstrates the effect of cultivation conditions on the production of natamycin. Of these conditions, the effect of oxygen limitation and type of inoculum were extensively investigated. Increasing the shaking speed and decreasing the medium volume improved both the volumetric and specific natamycin production. Also, decreasing the dissolved oxygen level in the cultivation medium through the addition of soluble biopolymer (alginate) resulted in a significant decrease in the natamycin yield without effect on the cell growth. On the other hand, spore inoculum yielded higher concentration of natamycin compared to the vegetative cells by about 40%. The maximal cell productivity based on biomass [Yp/x] of about 0.4 [g/g] was obtained by using shake flask of 50 ml working volume agitated at 200 rpm and the inoculum was in the form of spore 2 × 108 spores/ml. These results showed that the production process of natamycin is highly dependent on oxygen level in the cultivation medium and type of inoculum as well.

A new chitinase-producer strain Streptomyces glauciniger WICC-A03: isolation and identification as a biocontrol agent for plants phytopathogenic fungi

This study discusses the isolation and identification of a new Streptomycetes highly active chitinase producer. Fifteen strains were isolated from Malaysian soil samples. The isolate WICC-A03 was found to be the most active chitinase producer. Its antifungal activity was evaluated against many phytopathogens. The identification of WICC-A03 using phenotypic and genotypic methods strongly indicated that strain WICC-A03 belonged to the genus Streptomyces and displayed similarity (91%) with Streptomyces glauciniger. Thus, it was given the suggested name S. glauciniger WICC-A03 with accession number: JX139754. WICC-A03 produces extracellular chitinase in a medium containing 1.5% colloidal chitin in submerged culture on 144 h. The produced enzyme was partially characterised and its molecular weight of 50 kDa was determined by using SDS-PAGE. This study indicates that WICC-A03 is a potential chitinase producer for biocontrol of plant pathogens. Further experiments are being carried out to optimise medium composition and cultivation conditions under lab and bioreactor scale.

Preparation, characterization and anti-inflammatory activity of Swietenia macrophylla nanoemulgel

The advances in knowledge about production and stability of dispersed systems enable the development of differentiated vehicles such as nanoemulsions and nanoemulgels, which have been effectively used to increase the bioavailability and improve the stability of the active ingredients. Nowadays there is an intensely usage of natural bioactive materials as medicinal agent in pharmaceutical industries. Swietenia macrophylla oil is used due to the bioactivity of different parts of the plant as anti-inflammatory, anti-mutagenicity, anti-tumor. SM oil Nanoemulgels were prepared by incorporating nanoemulsion with hydrogel. First by preparing mixtures of oil, glycerol with sucrose ester (Laurate, Oleate and Palmitate) to produce pre-nanoemulsion using phase inversion technique, then nanoemulsion was produced using self-emulsification technique. After that, hydrogel was added to nanoemulsion to produce nanoemulgel. It was found that 50% oil with sucrose laurate 20% and 30% glycerol was able to produce pre-nanoemulsion, and then it was diluted with water under gentile agitation to produce nanoemulsion with droplets size 114 nm, low size distribution 0.163 and low zeta potential -43.1 mV. The optimal nanoemulsion formulation was mixed with different grades of hydrogel Carbopol 934 and 940 to produce nanoemulgels. It was found that Carbopol showed no influence on the oil droplets size with a range from 113 to 117 nm, size distribution from 0.155 to 0.163 and zeta potential range from -43.4 to -44.6 mV. In addition, it was able to produce a stable nanoemulgel at different temperatures 4°C, 25°C and 40°C when stored for one year and showed priority as thickening agent in relation to texture and rheological properties when compared to Carbopol 934. The anti-inflammatory test using carrageen an induced rat paw edema method for Swietenia macrophylla oil was carried and it was found that the inflammation inhibition of SM oil was higher for nanoemulgel compared to oil solution.

The preparation and evaluation of self-nanoemulsifying systems containing Swietenia oil and an examination of its anti-inflammatory effects

There is an increasing trend among pharmaceutical industries to use natural bioactive materials as medicinal agents and to use new technologies such as self-nanoemulsifying systems. The solubility and bioavailability of poorly soluble drugs can be enhanced by self-nanoemulsifying systems. Swietenia oil is frequently used because of its antimicrobial, antimutagenic, and anticancer bioactive medical properties. This study was conducted to develop self-nanoemulsifying systems for Swietenia oil that will enhance the anti-inflammatory activity of the oil. The self-emulsifying systems developed for Swietenia oil in this study were constructed using ternary phase diagrams and contained the nonionic surfactants Labrasol®, Tween 20, Capmul®, and Labrafil®. The effect of these surfactants on the formulation was examined. The mean droplet size of Swietenia oil as well as their distribution, appearance, viscosity, and spreading times were studied to find the optimum formula, which contained droplets that were less than 200 nm. The next step was to test the anti-inflammatory properties of the optimum formula using a carrageenan-induced rat paw edema test. The results from this test were compared to the oil solution. Different oil/surfactants mixtures had various emulsification properties that were related to the size of their droplets. Tween 20 is a good surfactant to use in self-emulsifying systems because it produces droplets of nano-size. Mixtures of Capmul/Labrasol at a ratio of 2:1 and Labrafil/Tween 20 at a ratio of 1:2 were able to produce self-nanoemulsifying formulations containing Swietenia oil concentrations that ranged from 20%–50%. Nanoemulsion occurred when the size of the droplets fell below 200 nm with low size distribution (<0.3) after being gently mixed with water. It was found that the hydrophilic/lipophilic balance value affected the ternary phase diagram behavior of Swietenia oil and surfactants. In addition, the anti-inflammatory properties of Swietenia oil were greater in the self-nanoemulsifying systems than in the oil solution.

Recent Progress on the Development of Antibiotics from the Genus Micromonospora

The emergence of a large number of antimicrobialresistant organisms is a cause for concern. Nature is historically the source of drugs; indeed a considerable number of drugs have been developed from microorganisms, and are now used daily in the treatment of infectious diseases. However, the introduction to the pharmaceutical market of new therapeutic molecules has decreased during the last two decades. In this review, the genus Micromonospora is proposed as a biofactory for production of new antibiotics. The genus Micromonospora has been investigated extensively and more than 100 antibiotics have been isolated from diverse Micromonospora strains. In addition, recent developments in analytical, biological and bioinformatics screening tools used in the discovery of new therapeutic compounds are described. It may be possible to revive formerly used antibiotics produced by Micromonospora and study of this genus may facilitate discovery of novel bioactive molecules.

Development of Fed-Batch Cultivation Strategy for Efficient Oxytetracycline Production by Streptomyces rimosus at Semi-Industrial Scale

Oxytetracycline (OTC) production byStreptomyces rimosus was studied in batch and fed-batch cultures in shake flask and bioreactor levels using semi-defined medium. First, the effect of glucose concentration on OTC production and growth kinetics was studied intensively. The optimal glucose concentration in the medium was 15 g/L. Higher glucose concentrations supported higher biomass production by less volumetric and specific antibiotic production. Based on these data, cultivations were carried out at semi-industrial scale 15 L bioreactor in batch culture. At bioreactor level, cell growth and OTC production were higher compared to the shake flask culture by about 18 and 38%, respectively. During the bioreactor cultivation, glucose was totally consumed after only 48 h. Thus, the fed-batch experiment was designed for mono-glucose feeding and complete medium feeding to increase the OTC production by overcoming carbon limitations. The results showed that the fed-batch culture using constant glucose feeding strategy with rate of 0.33 g/L/h produced 1072 mg/L. On the other hand, feeding with complete medium resulted in 45% higher biomass but less OTC production by about 26% compared to mono-glucose fed culture. A further improvement in this process was achieved in by keeping the dissolved oxygen (DO) value at 60% saturation by cascading the glucose feeding pump with the DO controller. The later feeding strategy resulted in higher antibiotic production, reaching 1414 mg/L after 108 h.

Development of avocado oil nanoemulsion hydrogel using sucrose ester stearate

Article history: Received on: 17/06/2013 Revised on: 23/07/2013 Accepted on: 07/08/2013 Available online: 31/12/2013 Nanoemulsion is submicron sized emulsion typically in the range of 20-200 nm. Avocado oil is often used in herbal skin care. The aim of this study was to characterize nanoemulsion hydrogel prepared using avocado oil and sucrose ester stearate as surfactant. The nanoemulsion hydrogel were prepared by nanophase emulsification technique. These formulations were examined using zetasizer to determined the mean diameter of dispersed oil droplets, polydispersibility index (PDI) and zeta potential. Moreover viscosity of the prepared nanoemulsion hydrogel were studied. The results reveled that nanoemulsion prepared with 60% w/w oil, 24% w/w glycerol and 16% w/w surfactant showed droplets size below 200 nm with good polydispersibility index and zeta potential < 30 mV. The optimum formulation of nanoemulsion was prepared in the form of nanoemulsion hydrogel using carbopols 934 and 940. The results of the viscometer for the nanoemulsion hydrogel showed that the storage modulus (G’) which describes the elasticity of the component were greater than the loss modulus (G”) values which reveals the viscosity of the component.

Antioxidant Compounds of the Edible Mushroom Pleurotus ostreatus

Mushrooms have been used since centuries in many ancient cultures as source of food and medicine. However, until now the therapeutic values of mushrooms position this group of macrofungi as one of the major component in traditional medicine practice especially in South East Asia and China. Of different species of known mushrooms, Pleurotus spp. is widely known as part of food chain based on its high nutritional value. However, of the more than 70 species known, only few species are cultivated in mass production and used such as P. ostreatus, P. florida, and P. ajor-caju. However, P. ostreatus (widely known as oyster mushroom) received more attention in food industries based on its high growth rate and ease of cultivation using different substrates. This mushroom is rich of wide range of bioactive molecules of proven medicinal values with many therapeutic activities as anticancer, immunomodulatory, antiapoptotic, anti hypocholesterolemic, anti hyperglycemic, antimicrobial, anti-inflammatory, anti-osteoporetic, and many others. This work focuses on reviewing on the different classes of oyster mushroom bioactive compounds of antioxidant activities such as phenolics, beta carotene, lycopene, ascorbic acid, tocopherols, and ergosterols. This review provides also comprehensive information on the recent research to enhance the antioxidant properties through alteration of the cultivation strategy and addition of some compounds during the cultivation of P. ostreatus.

Production of monoclonal antibody, Anti-CD3 by hybridoma cells cultivated in Basket Spinner under free and immobilized conditions

Background Monoclonal antibodies (Mabs) have been recently used for the treatment of virtually every debilitating disease. Packed-bed bioreactors have been used for the cultivation and production of a wide range of cell lines and biologics including MAbs. The principle behind a Packed-bed bioreactor is that the cells are being immobilized within a suitable stationary matrix which is represented by the bed. Packed-bed bioreactors also have the advantage of being capable of generating high cell densities with a low concentration of free cells in suspension; hence, simplifying downstream processing. The present work was designed to compare between the cultivation of hybridoma cells as well as the production of OKT3 MAb in free and immobilized culture conditions.