Optimization of Biosurfactant Production by Bacillus licheniformis Isolated from Oil Contaminated Egyptian Soil
text
article
2011
eng
OPTIMAL conditions for obtaining elevated biosurfactant production by a local strain of Bacillus licheniformis strain No. 5 were investigated. Modified minimal salt medium, pH 7.0, containing crude oil (1 %), urea (2 g/l), KH2PO4 + K2HPO4 (2+2 g/l), MgSO4 (0.2 g/l), yeast extract (1 g/l), and trace elements solution (0.1 %) was found to be the most suitable for growth and emulsifying activity by this bacterium. High biosurfactant production was obtained after incubation for 7 days at 30°C. By providing the previous conditions, the emulsion index (E24%) was increased 3–fold as compared to that obtained via growth in the original minimal salt medium. In bioreactor batch culture, an agitation speed of 300 rpm attained the highest microbial growth (1.9 g cell dry weight/l) and an E24= 50.90 % after 7 days of incubation. In fed-batch culture, the pulsed addition of crude oil during the first 2 – 3 days of incubation enhanced the emulsification activity by 1.3–fold. The greatest E24 was obtained using black grain oil (89.09 %), followed by that obtained against diesel oil (87.27 %). The highest stability of emulsion index was recorded on diesel oil, which remained stable for 10 days (E240 = 81.81 %). The biosurfactant showed an almost stable surface activity profile over a wide range of pH values (from 6 to 12). The maximum emulsification activity was obtained at pH 8. The reduction in E24 after exposure of the biosurfactant to 121oC for 15 min against diesel oil and toluene was 43.7 % and 28.6 %, respectively. Chemical analyses of the purified biosurfactant showed that it is a lipoprotein. Significant emulsification activity was detected towards different aliphatic and aromatic hydrocarbons and vegetable oils. The purified biosurfactant contained 41.7% C, 7.4% H and 5.8 % N and was comprised of 36.2% proteins, 12.3% lipids and 5.6 % carbohydrates.
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
1
20
https://ejm.journals.ekb.eg/article_260_e04edab90e084cf190a77c6f12bdabe6.pdf
dx.doi.org/10.21608/ejm.2011.260
Enhanced Production of Biosurfactants by Marine Pseudomonas aeruginosa
text
article
2011
eng
BIOSURFACTANTS are valuable microbial amphiphilic molecules with effective surface-active and biological properties applicable to several industries and processes. Microbes synthesize them, especially during growth on water-immiscible substrates, providing an alternative to chemically prepared conventional surfactants. The objective of this research was to evaluate factors affecting surfactant production from Pseudomonas aeruginosa which was dependent on some factors including the carbon source, medium composition, pH, temperature and duration of incubation. Use of glucose as a carbon source enhanced the production more than the other carbon sources evaluated. The Plackett-burman statistical design was used to optimize culture conditions and evaluate the most significant variables affecting surfactant production. (NH4)2SO4( 5g/l) and Na2HPO4 (2g/l) were the most significant variables affecting biosurfactant production (emulsification activity) which was increased up to 1.2 fold. The optimum medium composition for biosurfactant production is as follows (g/l) : (NH4)2SO4, 5; KH2PO4 , 5; MgSO4.7H2O , 1.5 ; glucose, 25; Na2HPO4 , 2; Na Cl, 2 and yeast extract , 0.2 0The optimum temperature and pH were 35°C and 6, respectively. Two days of incubation gave the highest production and increased biosurfactant yields up to 1.3 fold. Biosurfactant crude extract showed remarkable stability over a wide range of pH (6-10) and temperature (50-90ºC).
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
21
38
https://ejm.journals.ekb.eg/article_261_6f93c316a5105663acacf50facb90961.pdf
dx.doi.org/10.21608/ejm.2011.261
Production, Partial Purification and Some Properties of α-L-Arabinofuranosidase from Chaetomium thermophile and Talaromyces thermophilus
text
article
2011
eng
THE PRODUCTION of extracellular α-L-arabinofuranosidase (ABFase), partial purification and some of its properties by locally isolated strains of Chaetomium thermophile and Talaromyces thermophilus were studied. The best static culture conditions for the enzyme production were 2% sugar beet pulp; pH 5.0 and 45ºC for both strains. The best nitrogen source is ammonium sulphate for C. thermophile and yeast extract for T. thermophilus. The enzyme was partially purified from the culture supernatant by precipitation with ammonium sulfate treatment, gel filtration on Sephadex G100, with purification fold 15.89 and 8.32 for C. thermophile and T. thermophilus, respectively. The purified enzyme of both fungi displayed an optimal activity at 50 ºC. The enzyme was stable at temperatures between 30-70 ºC. The optimum pH for C. thermophile was 5.5 and the enzyme was stable at pH between 3.0 – 6.5. While the optimum pH for T. thermophilus was 6.5 and the enzyme was stable at pH between 3.0 – 7.5.
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
39
54
https://ejm.journals.ekb.eg/article_262_6e79e8f874a93bec180c2429f9e354a6.pdf
dx.doi.org/10.21608/ejm.2011.262
Production of a Novel Halophilic Dextranase from a Honey Isolate, Bacillus subtilis NRC-B233 under Solid-state Fermentation
text
article
2011
eng
A GRAM-POSITIVE, sporulating halophilic bacteria, designated NRC-B233, was isolated from the honey produced in Saudi Arabia. It was identified by the 16-23S intergenic region as Bacillus subtilis NRC-B233. Screening of the wastes and agro-products for dextranase production under solid state fermentation showed that corn flour was the best substrate (61.323 U/g). The optimum conditions for dextranase productions were 37°C, pH 9, 32 hr incubation period, and 200 % moisture content. The most favorable nitrogen and carbon sources for enzyme production were 2% peptone and 5% starch (1076.768, 1553.364 U/g). respectively. A unique character of this isolate is its ability to continuously produce dextranase in the absence and presence of NaCl 5-20 g/l. The addition of 0.175 Mm CrCl3 increased the dextranase production about 4.5 fold. The enzyme has been partially purified about 112-fold from crude extract by only two purification steps involving ultra-filtration. The purified dextranase showed its maximum activity at pH 9.2 and 70ºC. It retained full activity (100%) at 75ºC for one hour. Dextranase activity increased about four-fold in the presence of 10% NaCl. On the other hand, CaCl2 (0.050M), EDTA (0.100M), and KCl (0.100M) had great influence in enzyme activity. The enzyme showed variable degradation effects on different types of dextran and its derivatives.
These results suggest that the dextranase secreted by Bacillus subtilis NRC-B233 is industrially important from the perspectives of its activity at across pH range (5.0–10.0), its thermo-activity in addition to its halophilic character and its ability to degrade different types of α -1,4 and α-1,6 glycosidic linkages.
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
55
78
https://ejm.journals.ekb.eg/article_263_2aca0dc6e861b92089d01d2c4f2009fc.pdf
dx.doi.org/10.21608/ejm.2011.263
Characterization of Xylanase Produced by Aspergillus niger Fermented on Corn Cob
text
article
2011
eng
THE USE of waste as a raw material is important for government economy and natural balance. This article investigates a strain of Aspergillus niger for xylanase production in solid state fermentation (SSF) using different agricultural residues without pretreatment. The organism produced 164.4 (µ mol/ ml/ min) of xylanase in a static flask on a corn cob, an inexpensive lignocellulosic biomass, without enrichment of medium (only distilled water). Using surfactant solution (Tween 80, 1%) for enzyme extraction from solid substrate increased the yield by 52.5 %. Maximum xylanase activity was recorded at 55°C, with high activity at a wide range of temperature (50 - 60°C). The enzyme produced on corn cob showed good thermal stability with residual activity of 62.1 and 54.3 % after 2 hr incubation at 50 and 60°C, respectively. The addition of glycerol (50 %) improved stability against temperature by 19.9 % after incubation at 60°C for 1hr, and 17.8 % after incubation at 60°C for 2 hr. The optimum pH for the enzyme activity was 4.5, increasing pH causing decreasing in activity. Xylanase enzyme was stable at different pH’s after 1 hr with a remaining activity of 89.6 % and 55.0 %, respectively at pH 4.0 and 9.0. The enzyme possessed 70.6 and 37.6 % of its activity by storage at room temperature after 10 and 30 days. In the presence of metal ions such as Na2+, Ca2+ and protein disulphide reducing agents such as dithiothreitol (DTT), the activity of the enzyme was increased by 34.9, 10.7 and 32.8 %, respectively. Sodium dodecyl sulphate (SDS) and Cu2+ ion strongly inhibited the enzyme by 56.8 and 23.7 %, respectively. Saccharification of different wastes by the enzyme was studied. The highest yield of reducing sugars (20.3 mg/ 200 mg dry weight substrate) was obtained from corn cob with maximum saccharification after 72 hr (71.8 %) as compared to other wastes.
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
79
94
https://ejm.journals.ekb.eg/article_264_5de5fb51ecc544e8f31c3ca5b73aa9df.pdf
dx.doi.org/10.21608/ejm.2011.264
Regulation of Eurotium repens Reproduction and Secondary Metabolite Production
text
article
2011
eng
EUROTIUM repens (Anamorph Aspergillus repens) was isolated from spoiled fruit. It reproduced sexually at different sucrose concentrations up to 50% (w/v); water activity, 0.79. It reproduced asexually at high sucrose concentration 60% (w/v) water activity, 0.75. The concentrations of all detected amino acids were higher in the teleomorph than the anamorph except that of glycine, while aminoadipic acid and alanine were detected in teleomorph only. The extracellular secondary metabolites produced by the teleomorph and anamorph stages were variable and different except epoxysuccinic acid and 2-pyruvylamino benzamide which were produced by the two stages. Glycine, arginine and calcium chloride unlike glutamic acid, aspartic acid and alanine, plays an important role in the induction of teleomorph stage formation at high sucrose concentration 60 % (w/v).
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
95
108
https://ejm.journals.ekb.eg/article_265_7ad1dfcf4a529c32aee61587efcb1fc6.pdf
dx.doi.org/10.21608/ejm.2011.265
Production of Polyhydroxyalkanoate (PHAs) and Copolymer [P(HB-co-HV)] by Soil Bacterial Isolates in Batch and Two-Stage Batch Cultures
text
article
2011
eng
NINETY TWO local bacterial isolates, from the rhizosphere and soil around the root system of bean (Vicia faba) grown in Kalubia Governorate in Egypt, were bio-prospected for polyhydroxyalkanoate (PHA) accumulation. Three isolates accumulated ≥ 20 % of PHAs, they were identified as Pseudomonas fluorescens S48, Bacillus megaterium 7A and B. megaterium UBF19. The tested isolates gave the maximum PHAs content on basal medium containing glucose and ammonium sulfate at C/N ratio of 30/1 after 72 hr at 30oC using shake flask culture technique. Two-stage batch were implemented with varying loading levels of nitrogen and phosphorus, inoculated with washed cells. Nitrogen omission of 70 % led to increase the PHAs content by 19 %, 3% and 8.5 % using washed cells of Ps. fluorescens S48, B. megaterium UBF19 and Bacillus megaterium 7A, respectively comparing with batch production on the same medium after 72 hr. The Copolymer poly(hydroxybutyrate-co-hydroxyvalerate) [P (HB-co-HV)] content level was increased when valeric/glucose (V/G) was 0.19 mol.mol-1 after 96 hr being 25.97 % and 20.11 % by Ps. fluorescens S48 and B. megaterium UBF19, respectively and reached 23.73 % by B. megaterium 7A at propionic/glucose (P/G) of 0.5 mol.mol-1. The corresponding highest values of valeric content of copolymer at V/G 3.08 mol.mol-1 were 63 %, 49 % and 45 %, respectively,comparing with other V/G ratios by using GC analysis . Replacing glucose with 2 % corn oil or 1 % soybean oil increased the PHAs content of Ps. fluorescens S48 cells to 54.21 % and 52.12 %, respectively, after 72 hr.
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
109
123
https://ejm.journals.ekb.eg/article_266_da499b5a36d5efb1abbea639fd9202a0.pdf
dx.doi.org/10.21608/ejm.2011.266
Production Conditions of Exopolysaccharide from Bacillus megaterium Identified by 16S rRNA Gene Sequencing
text
article
2011
eng
THE BACILLUS megaterium exopolysaccharide (EPS) producer was isolated from the Egyptian soil and identified by molecular biology technique (16S rRNA). It was found that the exopolysaccharide showed a high yield after 72 hr, with an initial pH of 5.0, in 250 ml Erlenmeyer flasks containing 50 ml of culture, the medium having 2% sucrose as a sole carbon source. The yeast extract (0.1%) and ammonium chloride (0.1%) were the best organic and inorganic nitrogen source, respectively, as they gave the maximum EPS production. Optimum incubation temperature was found to be 35 C. Pretreated molasses from sugarcane and sugarbeet were used as a carbon source and they gave a considerable yield (~ tow fold) in relation to sucrose. The pretreatment of molasses by sulfuric acid showed a high yield of polysaccharide and maximum yield coefficient.
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
125
140
https://ejm.journals.ekb.eg/article_267_a6a612b909571d4df8656b5f314bfcd5.pdf
dx.doi.org/10.21608/ejm.2011.267
Functional Change of Dextran-modified α-amylase from Bacillus acidocaldarius
text
article
2011
eng
αAMYLASE from Bacillus acidocaldarius was modified by covalent coupling to activated dextran with retained activity of 77.7 %. After conjugation, the enzyme was stable within a broader pH range than the native enzyme and its optimum temperature increased by 10C compared to the native enzyme. The conjugated αamylase exhibited a higher Km (Michaelis constant), lower Vmax (maximal reaction rate) and lower EA (activation energy) than the native enzyme. Covalent attachment of - amylase to activated dextran protected the enzyme against heat inactivation. In the presence of the substrate, the conjugated enzyme retained 68.2 % of its original activity after incubation at 70C for 30 min which was more than that retained by the native enzyme (50.3 %) under the same conditions. The calculated t1/2 (half-life time) values of heat inactivation energy at 50, 60 C were 89 and 56 min, respectively for the conjugated enzyme, whereas at these temperatures the native enzyme was less stable (t1/2 60 and 47 min, respectively). The deactivation rate constant at 80 C for the conjugated α-amylase is about 11.9x10-3/ min, which is lower than that of the native enzyme (14.8x10-3/ min). Conjugated α-amylase was more stable against chemical denaturation than the native enzyme, and retained 70.6% of its activity in presence of CuSO4 (10 mM) while the native form of retained only 34.1%
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
141
152
https://ejm.journals.ekb.eg/article_268_67d32b80c9a1635203d0d20b2f368f13.pdf
dx.doi.org/10.21608/ejm.2011.268
Potency of Composts and their Teas Applied to Sandy Soil on Controlling Damping –off Disease and Peanut Growth and Yield
text
article
2011
eng
IN A GREENHOUSE trial, peanut seeds (Arachis hypogaea) ……were sown in a potted sandy soil amended with tea-deprived plant residues compost (TDPC), tea-deprived cattle manure compost (TDCC), teas of such composts (PRCT& CMCT) or intact forms of those composts (IPRC& ICMC). Half of the experimental treatments were infected with the fungus Rhizoctonia solani which induces damping- off disease. Fungicide "Rhizolex" was used for the unamended infected pots. The following results were obtained:
1-The organic treatments exerted significant reductions of pre-and post-emergence damping –off disease and increased the healthy survival of peanut plants, as compared with the un-composted control, of the fungal infected pots. Nevertheless, the fungicide treatment surpassed those of compost forms in such concern. 2-Nodulation status of peanut roots was severely injured by disease incidence but improved by the introduced organics. 3-Aspects of plant growth, crop yield and its components, as well as major biochemical constituents of peanut pods and straw, increased with application of compost variables, generally in both the uninfected and infected treatments. 4-Differences between the particular forms of plant residues compost and animal manure compost were mostly insignificant, concerning their effect on the experimental measures. 5-The positive action of the applied compost forms revealed the order: ICMC=IPRC > IPRC>TDCC= TDPC> CMCT> PRCT. Such order reflected the extent of potency of mature composts, in general, and their intact forms, in particular, as plant growth stimulators and natural biocontrol agent
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
153
175
https://ejm.journals.ekb.eg/article_269_5811c3ab62d18d5935f9c387895bef7b.pdf
dx.doi.org/10.21608/ejm.2011.269
Biological Evaluation of Fungal Deteriorated Archeological Wood (Islamic Period) and the Impact of Using Some Fungicides
text
article
2011
eng
EIGHTY SEVEN fungal isolates were obtained from the surface of biodeteriorated ceiling wood (No.1803, 1539) from the Islamic museum, Cairo, Egypt (Islamic period). Isolates belonging to eight main genera of fungi were identified, in the following frequencies: Acremonium 2.3%, Alternaria 11.5%, Aspergillus 37.8%, Botryotrichum 2.3%, Epicoccum 3.5%, Fusarium 6.9%, Penicillium 29.9% and Stemphylium 5.7%. In a series of trials , cellulase production was maximal for all fungal strains when grown on medium containing 4-6 % of wood straw ( at pH 4.5-5 after 1015 days at 30°C, whereas the maximum production of pectinase was attained on medium containing 6% wood straw at pH 4.5-5 after 1015 days at 30°C -35°C.
Application of the fungicides dichloroxylenol, paracresol and pentachlorophenol are recommended for use at 1000, 500 and 1000 ppm respectively, based on protection of artificially infected wood. Infected wood lost 40.1% of its bending strength, but showed increased density and water absorption compared with non infected wood. The lowest bending strength loss was attained with dichloroxylenol( 14.5%) followed by wood treatment with pentachlorophenol or paracresol (34.2%).
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
177
192
https://ejm.journals.ekb.eg/article_270_92f2933864fbb582d62634c3fde6739e.pdf
dx.doi.org/10.21608/ejm.2011.270
Growth and Yield Responses of Tomato ( Lycopersicon esculentum ) Grown under Soilless Cultivation to Application of Azospirillum, Azotobacter and Nitrogen
text
article
2011
eng
THIS STUDY was undertaken to investigate the possibility of .using Azospirillum brasilense and Azotobacter chroococcum applied with inorganic nitrogen to enhance tomato (Lycopersicon esculentum, Mill) production in soilless systems.The effect of inoculation with A. brasilense and / or Azoto. chroococcum with the application of 75 % (of the recommended dose) of N2 on certain tomato growth parameters (shoot height, number of leaves, and fresh and dry weights of plants) after 30, 60 and 90 days of transplanting were determined. In addition, total yield, mean fruit weight, and the number of fruits per plant were evaluated in plants inoculated with the two bacteria (separately or in combination) with 75 % N2, and plants inoculated with 75 % N2 (control 1) and 100 % N2 (control 2). Plants inoculated with a mixed inoculum of A. brasilense and Azoto. chroococcum with 75 % N2 gave the highest values of the growth parameters tested while plants inoculated with 75 % N2 (control 1) gave the lowest. The same treatment also resulted in the highest tomato yield, mean weight and number of fruits per plant followed by plants treated with A. brasilense and 75 % N2. The responses to the tested biofertilizers on nitrogen, phosphorous and potassium (NPK) uptake, the population of diazotrophic bacteria and nitrogenase and dehydrogenase activity of the tested bacteria on the rhizosphere of tomato showed that the mixed inoculum of A.brasilense and Azoto. chroococcum with 75 % N2 gave the highest NPK uptake levels after 30, 60 and 90 days of transplanting. The same treatment gave the highest population of diazotrophic bacteria and dehydrogenase and nitrogenase activity of the tested bacteria compared with the plants inoculated with a single organism or controls. In contrast, control 1 gave the least values among all treatments. This study shows that inoculation of tomato plants with Azospirillum brasilense and Azotobacter chroccocum have a significantly beneficial effect on tomato yield under soilless cultivation.
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
193
211
https://ejm.journals.ekb.eg/article_271_3720cc50e20405cbdeb2d443205b821f.pdf
dx.doi.org/10.21608/ejm.2011.271
Sorption of Cadmium and Lead Ions by Cunninghamella elagans Lender ML2
text
article
2011
eng
CUNNINGHAMELLA elegans Lender was isolated from agricultural field treated with sewage industrial effluents. It was selected on the basis of its high frequency for the biosorption potential evaluation of cadmium and lead. Alkali pretreated dead biomass was used for biosorption experiments. The effects of biomass concentration, initial metal concentration, pH, contact time, temperature and agitation rate were studied. The maximum uptake capacities of cadmium and lead ions are 59 mg/g and 71 mg/g dry wt biomass at an initial concentration of metal ions 300 mg/L and 200 mg/L biomass dosage, respectively. The optimum pH values for cadmium and lead biosorption were 5.0 and 6.0. The best temperature was 25oC for cadmium and lead ions. Maximum uptake of cadmium was achieved after 60min, while for lead after 30 min. The best agitation rate was 120rpm for both metal ions removal. The technique of scanning electron microscope coupled with energy dispersive X-ray analysis (EDAX) shows that cadmium and lead were exchanged with elements present on the surface of native cells of C. elegans Lender ; thereby suggesting ion exchange as one of the dominant mechanisms of metal biosorption for this fungal strain. Alkali pretreated biomass was tested to remove cadmium and lead ions from three wastewater samples. Cadmium and lead ions were effectively eluted by 15 mM HNO3 and 10 mM EDTA, respectively.
Egyptian Journal of Microbiology
National Information and Documentation Center (NIDOC), Academy of Scientific Research and Technology
0022-2704
46
v.
1
no.
2011
213
231
https://ejm.journals.ekb.eg/article_272_0e76c75510b8ed5eede5f1d645d1df1f.pdf
dx.doi.org/10.21608/ejm.2011.272