Exobiopolymer from polyhydroxyalkanoate-producing transgenic yeast

Recently, the wild type yeast Kloeckera sp. strain KY1 was equipped in their cytoplasm with the phaABC operon containing genes phbA, phbB and phbC of the PHA biosynthetic pathway of Ralstonia eutropha. Unpredicted, resulted transgenic yeast strain KY1/PHA was able to synthesize another exopolymer beside the production of PHA. Subsequently, produced exopolymer was subject for further identification, characterization and analysis. Partial purification of exopolymer was performed and characterized as glycoprotein. HPLC analysis of the polymer revealed the presence of a fructose chain. The functional group analysis by FT-IR spectroscopy showed the presence of carboxyl, hydroxyl and amid groups. The exopolymer was soluble in water and insoluble in any tested organic solvents and could flocculate kaolin suspension (5 g/l) over a wide range of pH (pH 3 to 9) and temperature (5 to 50°C) tested in the presence of CaCl2. The highest flocculation activity of 99% for kaolin suspension was achieved at a dosage of 13 mg/l. Thus, it is possible that this glycoprotein could be substituted for a commercial polymer with respect to flocculation.Key word: Transgenic yeast, bioflocculant, exopolymer, glycoprotein,  spectroscopic analysis

Bioflocculation of Basic Dye onto Isolated Microbial Biopolymers

Three purified biopolymers isolated from Bacillus velezensis (40B), Bacillus mojavensis (32A) and Pseudomonas (38A) strains were evaluated for dye decolourization as bioflocculants. The decolourization capacity of the three polymers was inspected using C.I 28 basic yellow dye as hazardous pollutant. The chemical compositions of these purified biopolymers were considered by HPLC and FTIR spectrum. The decolourization efficiency of the three purified biopolymers was determined using both real dye polluted wastewater (discharged from AKSA EGYPT acrylic fibres industry) and simulated synthetic wastewater. The maximum decolourization efficiencies of the purified biopolymers of the three studied strains (40B), (32A) and (38A) were 91, 89 and 88 %, respectively. The equilibrium of dye sorption process onto biopolymers was described using Langmuir isotherm equation. However, its kinetics follows the pseudo second order model. The thermodynamic examination investigated the exothermic and spontaneous nature of the decolourization process using the purified biopolymers. This work is licensed under a Creative Commons Attribution 4.0 International License

PROGNOSTIC SIGNIFICANCE OF CD56 EXPRESSION IN ACUTE LEUKEMIAS

Background. CD56 expression was extensively investigated in cases of acute leukemia. Many studies associated it with short overall survival, unfavorable outcome, lower rates or short complete remission, however the results remain controversial. Objectives. The aim of this study was to investigate the frequency and prognostic relevance of CD56 expression in patients with acute leukemia and to compare its value with other standard prognostic factors, such as age, gender, leukocytosis, morphologic subtypes, extramedullary invasion, cytogenetic abnormalities and performance status. Methods. Forty cases of acute leukemia treated at Ain Shmas University hospitals were investigated. They were classified by the French-American-British group (FAB) criteria, flow cytometry, and cytogenetics data. They included twenty cases of acute myeloid leukemia (AML) and twenty cases of acute lymphoblastic leukemia (ALL). Results. CD56 positive expression was detected in nine cases of AML (45 %), and only in two patients with ALL (10 %). The highest incidence of CD56 positivity was in FAB subtypes M1 (35 %) and M2 (35 %).Association studies between CD56 expression and other prognostic factors in AML cases showed no significant association with age, gender, clinical presentation, hematological data or cytogenetic risk groups. Incidence of relapse was higher in AML patients expressing CD56 than those who did not (66.7 % vs 10 %, P=0.01). Higher death rates were encountered in AML cases with CD56 expression than those without (55.6 % vs 10 %, P=0.032). Conclusions. CD56 antigenic expression in AML cases represents an adverse prognostic factor. It should be regularly investigated in cases of AML for better prognostic stratification and assessment. KEY WORDS: CD56; leukemia, myeloid; prognosi

Aminoglycoside Resistance Rates, Phenotypes, and Mechanisms of Gram-Negative Bacteria from Infected Patients in Upper Egypt

With the re-emergence of older antibiotics as valuable choices for treatment of serious infections, we studied the aminoglycoside resistance of Gram-negative bacteria isolated from patients with ear, urinary tract, skin, and gastrointestinal tract infections at Minia university hospital in Egypt. Escherichia coli (mainly from urinary tract and gastrointestinal tract infections) was the most prevalent isolate (28.57%), followed by Pseudomonas aeruginosa (25.7%) (mainly from ear discharge and skin infections). Isolates exhibited maximal resistance against streptomycin (83.4%), and minimal resistance against amikacin (17.7%) and intermediate degrees of resistance against neomycin, kanamycin, gentamicin, and tobramycin. Resistance to older aminoglycosides was higher than newer aminoglycoides. The most common aminoglycoside resistance phenotype was that of streptomycin resistance, present as a single phenotype or in combination, followed by kanamycin-neomycin as determined by interpretative reading. The resistant Pseudomonas aeruginosa strains were capable of producing aminoglycoside-modifying enzymes and using efflux as mechanisms of resistance. Using checkerboard titration method, the most frequently-observed outcome in combinations of aminoglycosides with β-lactams or quinolones was synergism. The most effective combination was amikacin with ciprofloxacin (100% Synergism), whereas the least effective combination was gentamicin with amoxicillin (53.3% Synergistic, 26.7% additive, and 20% indifferent FIC indices). Whereas the studied combinations were additive and indifferent against few of the tested strains, antagonism was never observed. The high resistance rates to aminoglycosides exhibited by Gram-negative bacteria in this study could be attributed to the selective pressure of aminoglycoside usage which could be controlled by successful implementation of infection control measures

[3H]Adenine is a suitable radioligand for the labeling of G protein-coupled adenine receptors but shows high affinity to bacterial contaminations in buffer solutions

[3H]Adenine has previously been used to label the newly discovered G protein-coupled murine adenine receptors. Recent reports have questioned the suitability of [3H]adenine for adenine receptor binding studies because of curious results, e.g. high specific binding even in the absence of mammalian protein. In this study, we showed that specific [3H]adenine binding to various mammalian membrane preparations increased linearly with protein concentration. Furthermore, we found that Tris-buffer solutions typically used for radioligand binding studies (50 mM, pH 7.4) that have not been freshly prepared but stored at 4°C for some time may contain bacterial contaminations that exhibit high affinity binding for [3H]adenine. Specific binding is abolished by heating the contaminated buffer or filtering it through 0.2-μm filters. Three different, aerobic, gram-negative bacteria were isolated from a contaminated buffer solution and identified as Achromobacter xylosoxidans, A. denitrificans, and Acinetobacter lwoffii. A. xylosoxidans, a common bacterium that can cause nosocomial infections, showed a particularly high affinity for [3H]adenine in the low nanomolar range. Structure–activity relationships revealed that hypoxanthine also bound with high affinity to A. xylosoxidans, whereas other nucleobases (uracil, xanthine) and nucleosides (adenosine, uridine) did not. The nature of the labeled site in bacteria is not known, but preliminary results indicate that it may be a high-affinity purine transporter. We conclude that [3H]adenine is a well-suitable radioligand for adenine receptor binding studies but that bacterial contamination of the employed buffer solutions must be avoided

Biosynthesis of biodegradable polyhydroxyalkanotes biopolymers in genetically modified yeasts

In the recent decade, biosynthesis of the degradable biopolymers polyhydroxyalkanotes in transgenic yeasts became an important research task. Most research strategies depend on either metabolic engineering or molecular approaches. In the present work, research compared PHA biosynthesis in two types of yeasts; Saccharomyces cerevisiae and a non-convenient Kloeckera spp.Yeast strains were equipped in their cytoplasm with the phaABCRe operon containing genes phbA, phbB and phbC of the PHA biosynthetic pathway of Ralstonia eutropha , which encode â-ketothiolase, NADPH-linked acetoacetyl-CoA reductase and PHA synthase, respectively. The transgenic strains Saccharomyces cerevisiae and Kloeckera sp. were able to produce PHA. The maximum content of the polymer detected in the recombinant strain INVSc1/PHA1 was 2.68 % and only poly-3-hydroxybutyrate (PHB) accumulated. However, the non-conventional transgenic strain KY1/PHA was able to accumulate as maximum of 7.06 % of the copolymer poly-(3-hydroxybutyrateco-poly-3-hydroxyvalerate) (PHV). Western blot analysis confirmed expression of the phaABCReoperonin the transgenic yeast strains. The nature of the PHA thus produced by all tested strains was analyzed by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy

PROGNOSTIC SIGNIFICANCE OF CD56 EXPRESSION IN ACUTE LEUKEMIAS

Background. CD56 expression was extensively investigated in cases of acute leukemia. Many studies associated it with short overall survival, unfavorable outcome, lower rates or short complete remission, however the results remain controversial. Objectives. The aim of this study was to investigate the frequency and prognostic relevance of CD56 expression in patients with acute leukemia and to compare its value with other standard prognostic factors, such as age, gender, leukocytosis, morphologic subtypes, extramedullary invasion, cytogenetic abnormalities and performance status. Methods. Forty cases of acute leukemia treated at Ain Shmas University hospitals were investigated. They were classified by the French-American-British group (FAB) criteria, flow cytometry, and cytogenetics data. They included twenty cases of acute myeloid leukemia (AML) and twenty cases of acute lymphoblastic leukemia (ALL). Results. CD56 positive expression was detected in nine cases of AML (45 %), and only in two patients with ALL (10 %). The highest incidence of CD56 positivity was in FAB subtypes M1 (35 %) and M2 (35 %).Association studies between CD56 expression and other prognostic factors in AML cases showed no significant association with age, gender, clinical presentation, hematological data or cytogenetic risk groups. Incidence of relapse was higher in AML patients expressing CD56 than those who did not (66.7 % vs 10 %, P=0.01). Higher death rates were encountered in AML cases with CD56 expression than those without (55.6 % vs 10 %, P=0.032). Conclusions. CD56 antigenic expression in AML cases represents an adverse prognostic factor. It should be regularly investigated in cases of AML for better prognostic stratification and assessment. KEY WORDS: CD56; leukemia, myeloid; prognosi