Biokinetic aspects for biocatalytic remediation of xenobiotics polluted seawater.

AIMS: This research was conducted to investigate the biocatalytic remediation of xenobiotics polluted seawater using two biocatalysts; whole bacterial cells of facultative aerobic halotolerant Corynebacterium variabilis Sh42 and its extracted crude enzymes. METHODS AND RESULTS: One-Factor-at-A-Time technique and statistical analysis were applied to study the effect of initial substrate concentrations, pH, temperature, and initial biocatalyst concentrations on the batch biocatalytic degradation of three xenobiotic pollutants (2-hydroxybiphenyl (2-HBP), catechol and benzoic acid) in artificial seawater (salinity 3·1%). HPLC and gas-chromatography mass spectroscopy analyses were utilized to illustrate the quantitative removal of the studied aromatic xenobiotic pollutants and their catabolic pathway. The results revealed that the microbial and enzymatic cultures followed substrate inhibition kinetics. Yano and Koga's equation showed the best fit for the biokinetic degradation rates of 2-HBP and benzoic acid, whereas Haldane biokinetic model adequately expressed the specific biodegradation rate of catechol. The biokinetic results indicated the good efficiency and tolerance of crude enzyme for biocatalytic degradation of extremely high concentrations of aromatic pollutants than whole C. variabilis Sh42 cells. The monitored by-products indicated that the catabolic degradation pathway followed an oxidation mechanism via a site-specific monooxygenase enzyme. Benzoic acid and catechol were identified as major intermediates in the biodegradation pathway of 2-HBP, which were then biodegraded through meta-cleavage to 2-hydroxymuconic semialdehyde. With time elapsed, the semialdehyde product was further biodegraded to acetaldehyde and pyruvic acid, which would be further metabolized via the bacterial TCA cycle. CONCLUSION: The batch enzymatic bioreactors performed superior-specific biocatalytic degradation rates for all the studied xenobiotic pollutants. SIGNIFICANCE AND IMPACT OF THE STUDY: The enzymatic system of C. variabilis Sh42 is tolerable for toxic xenobiotics and different physicochemical environmental parameters. Thus, it can be recommended as an effective biocatalyst for biocatalytic remediation of xenobiotics polluted seawater.

Novel mycosynthesis of cobalt oxide nanoparticles using Aspergillus brasiliensis ATCC 16404-optimization, characterization and antimicrobial activity.

AIMS: Investigate the capability of Aspergillus brasiliensis ATCC 16404 to mycosynthesize Co3 O4 -NPs. METHODS AND RESULTS: Mycelial cell-free filtrate of A. brasiliensis ATCC 16404 was applied for mycosynthesis of Co3 O4 -NPs. The preliminary indication for the formation of Co3 O4 -NPs was the change in colour from yellow to reddish-brown. One-factor-at a time-optimization technique was applied to determine the optimum physicochemical conditions required for the mycosynthesis of Co3 O4 -NPs and they were found to be: 72 h for reaction time, pH 11, 30°C, 100 rev min-1 for shaking speed in the darkness using 4 mmol l-1 of CoSO4. 7H2 O and 5·5% of A. brasiliensis dry weight mycelium (w/v). The mycosynthesized Co3 O4 -NPs were characterized using various techniques: spectroscopy including UV/Vis spectrophotometry, dynamic light scattering (DLS), zeta potential measurement, energy-dispersive X-ray analysis, Fourier transform infrared spectroscopy and X-ray diffraction; and vibrating sample magnetometry and microscopy including field emission scanning electron microscopy and high-resolution transmission electron microscopy. Spectroscopic techniques confirmed the formation of Co3 O4 -NPs and the microscopic ones confirmed the shape and size of the mycosynthesized Co3 O4 -NPs as quasi-spherical shaped, monodispersed nanoparticles with a nano size range of 20-27 nm. The mycosynthesized Co3 O4 -NPs have excellent magnetic properties and exhibited a good antimicrobial activity against some pathogenic micro-organisms. CONCLUSION: Ferromagnetic Co3 O4 -NPs with considerable antimicrobial activity were for the first time mycosynthesized. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of fungi as potential bionanofactories for mycosynthesis of nanoparticles is relatively a recent field of research with considerable prospects.

Physiochemical properties of Trichoderma longibrachiatum DSMZ 16517-synthesized silver nanoparticles for the mitigation of halotolerant sulphate-reducing bacteria.

AIMS: In order to efficiently control the corrosive sulphate-reducing bacteria (SRB), the main precursor of the microbial influenced corrosion (MIC) in oil industry, the ability of Trichoderma longibrachiatumDSMZ 16517 to synthesize silver nanoparticles (AgNPs) was investigated and their biocidal activity against halotolerant SRB was tested. METHODS AND RESULTS: The mycelial cell-free filtrate (MCFF) bioreduced the silver ions (Ag+ ) to their metallic nanoparticle state (Ag0 ), which was presumptively indicated by the appearance of a dark brown suspension and confirmed by the characteristic absorbance of AgNPs at ʎ422nm . One-factor-at-a-time technique was used to optimize the effect of temperature, time, pH, fungal biomass and silver nitrate concentrations, stirring rates and dark effect. The dynamic light scattering (DLS) analysis revealed average AgNPs size and zeta potential values of 17·75 nm and -26·8 mV, respectively, indicating the stability of the prepared AgNPs. The X-ray diffraction (XRD) pattern assured the crystallinity of the mycosynthesized AgNPs, with an average size of 61 nm. The field emission scanning electron microscope (FESEM) and high-resolution transmission electron microscope (HRTEM) showed nonagglomerated spherical, triangular and cuboid AgNPs ranging from 5 to 11 ± 0·5 nm. The Fourier transform infrared spectroscopy (FT-IR) analysis of the mycosynthesized AgNPs affirmed the role of MCFF as a reducing and capping agent. A preliminary suggested mechanism for mycosynthesis of AgNPs was elucidated. The mycosynthesized AgNPs expressed high biocidal activity against a halotolerant planktonic mixed culture of SRB. The HRTEM analysis showed a clear evidence of an alteration in cell morphology, a disruption of SRB cell membranes, a lysis in cell wall and a cytoplasmic extraction after treatment with AgNPs. This confirmed the bactericidal effect of the mycosynthesized AgNPs. CONCLUSION: The biocidal activity of the mycosynthesized AgNPs against halotolerant planktonic SRB makes it an attractive option to control MIC in the petroleum industry. SIGNIFICANCE AND IMPACT OF THE STUDY: This research provides a helpful insight into the development of a new mycosynthesized biocidal agent against the corrosive sulphate-reducing bacteria.

Synthesis of recyclable carbon/lignin biocomposite sorbent for in-situ uptake of BTX contaminants from wastewater.

In this work, both palm-date pits and pulping black liquor industrial wastes were recycled as low-cost starting materials for the production of three series of granule activated carbon (gAC)/Kraft lignin (KL) (gAC/KLx, x = 33, 50 and 67%) biocomposites using a one-pot solid-state method. The gAC/KLx biocomposites with defined characteristics were examined towards batch adsorption of BTX (Benzene, Toluene, and Xylene) in multi-solute salty wastewaters. Optimization of adsorption performances under different experimental conditions were carried out using high performance liquid chromatography (HPLC). Adsorption modeling versus contact time (0-12 h) and BTX concentrations (150-2250 mg/L) were examined using non-linear forms of nine kinetic and five isotherm equations to best understand gAC/KL0.5 suitability for BTX sorption/recovery processing. Accordingly, the gAC/KLx at KL blended ratio of 50% was found to be the topmost to achieve the highest BTX capacity even at broad ranges of water salinity (0-100 g/L) and pH (3-9) values. The adsorption mechanism found to best described by physico-sorption (E ≈ 0.12-1.38 kJ/mol) via the hydrophobic interaction and diffusion mechanisms. In respect to gAC/KL0.5 affinities, the sorption capacity followed the descending sequence of X ≥ T > B. Particularly, the maximum theoretical BTX capacity using the best fitted Langmuir-Freundlich model (L-FM) for gAC/KL0.5 was found to be slightly higher than obtained by gAC (363.9 and 360.1 mg/g, respectively), along with higher initial sorption (h) rate (≈742.47 mg/g.h) than of gAC (≈559.85 mg/g.h) and KL (≈22.22 mg/g.h). Batch BTX sorption/recovery processes and estimated cost suggested the effective utilization of gAC/KL0.5 as a promising in-expensive sorbent (0.31 ±â€¯0.05 US$/kg) for commercial decontamination of petroleum hazardous (BTX) pollutants from wastewaters up to five reuse cycles.

Statistical enhancement of lipase extracellular production by Bacillus stratosphericus PSP8 in a batch submerged fermentation process.

AIM: The aim of this study was to isolate and identify lipolytic bacteria. Perform a statistical stepwise physicochemical optimization for maximum production of extracellular lipase and its validation in a bioreactor. METHODS AND RESULTS: Several lipolytic bacteria were isolated from petroleum hydrocarbon-polluted soil. The strain expressing the highest lipase activity (47 U ml-1 ) was genetically identified as Gram-positive Bacillus stratosphericus PSP8 (NCBI GenBank accession no. MH120423). The response surface methodology (RSM)-central composite face centre (CCF) design of experiments was performed based on the preselected levels of the studied parameters obtained from the performed one-factor-at-a-time sequential experiments. A second-order polynomial model was predicted and improved the lipase production by approximately 1·6-fold. Preliminary scaling up of the validated optimized process was carried out in a batch 10-l stirred tank bioreactor, applying the optimum predicted operating conditions; pH 6·98, 34·8°C, 2·2 × 106 cells per ml, 200 rev min-1 , 4·82 g l-1 tributyrine concentration, 1% sucrose and 0·1% yeast extract. This yielded 89 U ml-1 at the late log phase of bacterial growth (48 h). Logistic kinetic model effectively characterized the submerged fermentation process, and the maximum specific growth and lipase production rates were estimated to be 0·338 and 0·164 h-1 respectively. CONCLUSIONS: The mesophilic and neutrophilic B. stratosphericus PSP8 isolated from petroleum hydrocarbon-contaminated soil is a proper source of lipase. The closeness of the predicted response with that of the experimental value and the enhancement of lipase productivity in fermenter scale by approximately 1·9-fold, showed that statistically optimized design can be used in order to improve the lipase production to meet the increasing demand. SIGNIFICANCE AND IMPACT OF THE STUDY: The RSM-CCF statistical optimization is useful for optimizing a large number of variables and studying their interactive effects on extracellular lipase production.

Batch bioethanol production via the biological and chemical saccharification of some Egyptian marine macroalgae.

AIMS: Marine seaweeds (macroalgae) cause an eutrophication problem and affects the touristic activities. The success of the production of the third-generation bioethanol from marine macroalgae depends mainly on the development of an ecofriendly and eco-feasible pretreatment (i.e. hydrolysis) technique, a highly effective saccharification step and finally an efficient bioethanol fermentation step. Therefore, this study aimed to investigate the potentiality of different marine macroalgal strains, collected from Egyptian coasts, for bioethanol production via different saccharification processes. METHODS AND RESULTS: Different marine macroalgal strains, red Jania rubens, green Ulva lactuca and brown Sargassum latifolium, have been collected from Egyptian Mediterranean and Red Sea shores. Different hydrolysis processes were evaluated to maximize the extraction of fermentable sugars; thermochemical hydrolysis with diluted acids (HCl and H2 SO4 ) and base (NaOH), hydrothermal hydrolysis followed by saccharification with different fungal strains and finally, thermochemical hydrolysis with diluted HCl, followed by fungal saccharification. The hydrothermal hydrolysis of S. latifolium followed by biological saccharification using Trichoderma asperellum RM1 produced maximum total sugars of 510 mg g-1 macroalgal biomass. The integration of the hydrothermal and fungal hydrolyses of the macroalgal biomass with a separate batch fermentation of the produced sugars using two Saccharomyces cerevisiae strains, produced approximately 0·29 g bioethanol g-1 total reducing sugars. A simulated regression modelling for the batch bioethanol fermentation was also performed. CONCLUSIONS: This study supported the possibility of using seaweeds as a renewable source of bioethanol throughout a suggested integration of macroalgal biomass hydrothermal and fungal hydrolyses with a separate batch bioethanol fermentation process of the produced sugars. SIGNIFICANCE AND IMPACT OF THE STUDY: The usage of marine macroalgae (i.e. seaweeds) as feedstock for bioethanol; an alternative and/or complimentary to petro-fuel, would act as triple fact solution; bioremediation process for ecosystem, renewable energy source and economy savings.

Immunogenicity and safety of autoclaved Leishmania major plus BCG vaccine in healthy Sudanese volunteers.

In a longitudinal study in the epidemiology of Leishmania donovani infection in an endemic focus in eastern Sudan, we observed that previous exposure or infection with Leishmania major appeared to protect against visceral leishmaniasis caused by L. donovani. We therefore conducted a study to test the safety and immunogenicity of a vaccine consisting of autoclaved L. major (ALM) plus BCG in inducing protection in vaccinated individuals. Leishmanin-negative healthy Sudanese volunteers were enrolled in the study and were divided into three groups: group (A) received ALM+BCG, group (B) received BCG alone, and group (C) received the vaccine diluent. The subjects were examined for their clinical and immunological responses before intervention, following intervention and 6-8 weeks after vaccination. Vaccinated subjects (group A) developed localized reactions at the sites of vaccine inoculation that ulcerated and healed within 4-6 weeks; 61.6% of them converted to leishmanin reactive following vaccination. Only one subject in group (C) became leishmanin-positive. A total 76.9% of the vaccinated volunteers in group (A) produced significant levels of interferon-gamma in response to L. major antigen. The vaccine produced significant cellular immune responses that may protect against natural challenge. None of the groups had systemic reactions and all the reactions observed in the vaccinated group were comparable with the BCG-vaccinated group.

Clinical, parasitological and immunological features of canal cleaners hyper-exposed to Schistosoma mansoni in the Sudan.

The present work was a longitudinal study on Schistosoma mansoni infection in occupationally hyperexposed canal cleaners in the Sudan and the influence of therapy on the parasitological and humoral immune parameters. Chronically infected canal cleaners (n = 28) were more resistant to reinfection (Fisher's exact test, P < 0.05) than newly recruited canal cleaners (n=17). Chronically infected canal cleaners had a significantly higher degree of Symmers' fibrosis (chi2 = 19.1, P < 0.0001), significantly larger portal vein diameter (P < 0.05) and enlarged spleen (chi2 = 4.2, P < 0.05) than recently infected, newly recruited canal cleaners. ELISA was used to detect IgG, IgA and IgM in response to whole worm homogenate (WWH) and cercarial homogenate (CH). Chronically infected canal cleaners had significantly higher IgG to WWH antigen than newly recruited canal cleaners and normally exposed individuals (P < 0.05), while both chronically infected and newly recruited canal cleaners had higher IgG levels to CH antigen than normally exposed individuals (P < 0.05). The newly recruited canal cleaners had a significantly higher IgM level to CH antigen than chronically infected canal cleaners (P < 0.05). The IgG level to WWH antigen increased significantly after treatment in newly recruited canal cleaners and normally exposed individuals (P < 0.05). The IgA level to CH antigen increased significantly after treatment in the chronically infected group (P < 0.05). Comparison of the serological parameters between the different study groups with regards to infection and treatment is discussed.

The significance of blood levels of IgM, IgA, IgG and IgG subclasses in Sudanese visceral leishmaniasis patients.

We developed an ELISA test using leishmania antigenic extracts to detect antigen-specific antibody responses, including subclass and isotype analysis, in visceral leishmaniasis (VL) patients from the Sudan. A total of 92 parasitologically proven patients were compared with cutaneous leishmaniasis, schistosomiasis, malaria, onchocerciasis and tuberculosis patients, as well as with healthy endemic and non-endemic controls. Some VL patients were examined before and after chemotherapy. VL patients showed significantly higher IgG responses compared with all other groups (93.4% sensitivity, 93.7% specificity), and higher (but not significantly) IgM responses. All groups showed low IgA levels. All IgG subclasses, IgG1, 2, 3, and 4, showed higher levels in patients than all other groups, with IgG1 and IgG3 levels being significantly reduced following treatment. The rank order for specificity and sensitivity for IgG subclasses was IgG3 > IgG1 > IgG2 > IgG4.

Proteins and amino acids of some local varieties of rice seeds (Oryza Sativa L.).

Proteins and amino acids in four local rice (Oryza Sativa L.) varieties were identified. Albumin and globulin were extracted from rice seeds, and the major promoters of these proteins were investigated by polyacrylamide gel electrophoresis to show their patterns. Amino acid composition of the rice seed were determined quantitatively and qualitatively, and classified according to their acidic, basic and uncharged polar groups. Essential amino acids for each variety were determined, and the hydrophobicity index value of Amber 33 was (0.6078), Mishkhab 1 (0.63372), Hybrid 2 (0.6523) and Hwazawi (0.7411).

Immunization of zebu calves against Fasciola gigantica, using irradiated metacercariae.

The pathogenesis of unirradiated, 3 krad-irradiated and 20 krad-irradiated metacercarial infections was compared in zebu calves studied over a 10-week period. Calves exposed to 1000 unirradiated metacercariae (mc) became hypoalbuminaemic, and showed elevated serum concentrations of liver enzymes, whereas neither of the other groups was significantly affected. At slaughter, a mean of 332 flukes was recovered from the 0 krad group, while only 23% and 12% of this number were recovered from the 3 krad and and 20 krad groups, respectively. All the worms recovered from the 20 krad group were stunted, and found in biliary ductules, but a mean of 13% of the flukes recovered from the 3 krad group were large, and dwelling in main bile-ducts. Liver lesions typical of acute fascioliasis were present in the 0 krad group, but lesions in the other groups, and particularly the 20 krad group, were far less severe. Judged on clinico-pathological criteria, a single vaccination of calves with 1000 3 krad-irradiated mc induced partial resistance to a challenge with 1000 normal mc eight weeks later, but the reduction in worm recovery was not statistically significant. There was less evidence of protection when two vaccinating doses of 3 krad mc were given within four weeks, with challenge at week 8, and a single vaccination was ineffective against a challenge four weeks later. However, when the irradiation dose was increased to 20 krad, a hgh level of resistance (69% worm reduction) was induced by a single vaccination, given eight weeks before challenge, and liver pathology was strikingly reduced in the vaccinated animals.

Studies on heterologous resistance between Schistosoma bovis and Fasciola gigantica in Sudanese cattle.

Using the local strains of Schistosoma bovis and Fasciola gigantica, it was shown that Sudanese zebu calves with mature primary infections of F. gigantica were highly resistant to challenge with S. bovis cercariae, and vice versa. Liver enzyme tests showed that, in both cases, the primary infections had caused some liver damage. Primary infection with irradiated S. bovis cercariae, which did not cause significant liver damage, did not protect significantly against challenge with F. gigantica.