Emergence and Genomic Characterization of a spa Type t4407 ST6-SCCmec Type IVa Methicillin-Resistant Staphylococcus aureus Strain Isolated from Al-Karak Hospital, Jordan.

Background and Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) is a major concern in Jordanian hospitals in terms of infection control. The purpose of this study was to identify the resistance patterns of Staphylococcus aureus strains isolated from surfaces of critical locations within the Al-Karak Governmental Hospital in 2019. Additionally, the study aimed to conduct whole-genome sequencing on the isolates. Materials and Methods: In February 2019, fourteen S. aureus strains were isolated from surfaces in critical sites in the Al-Karak Governmental Hospital. These isolates underwent antibiogram testing to determine their resistance profile. Genome sequencing using the Illumina MiSeq platform was applied to the extracted DNA from these isolates. The genomic data, including coding sequences, were analyzed to identify lineage, resistance genes, and plasmids. Results: The antibiogram results revealed that 11 of the 14 isolates were resistant to oxacillin, 6 to linezolid, and 1 to rifampicin, while none showed resistance to chloramphenicol. Eleven isolates were identified as MRSA, with a novel spa type (t4407) not previously reported in Jordan. High-quality sequencing data were obtained for only one isolate, i.e., A29, the genome showed 2,789,641 bp with a 32.7% GC content and contained 2650 coding sequences. Genomic analysis indicated the ST6 lineage, mecA gene (SCCmec type IVa(2B)), and a hybrid plasmid (pJOR_blaZ) carrying the blaZ gene for ß-lactam resistance. Genomic data were deposited in NCBI (CP104989). The A29 genome closely resembled an MRSA genome isolated from a Danish hospital in 2011. The SNP analysis revealed identical antimicrobial resistance genes in these two genomes. Conclusions: This study unveils the first genomic sequence of an MRSA isolate from Jordan, marked by distinctive genotypic traits. The findings enhance our understanding of the MRSA types circulating in Jordan and the region and substantiate the phenomenon of intercontinental MRSA transmission.

The ARISCAT Risk Index as a Predictor of Pulmonary Complications After Thoracic Surgeries, Almoosa Specialist Hospital, Saudi Arabia.

Background: Pulmonary complications after thoracic surgery are common and are associated with prolonged hospital stay, higher costs, and increased mortality. This study aimed to evaluate the value of The Assess Respiratory risk in Surgical Patients in Catalonia (ARISCAT) risk index in predicting pulmonary complications after thoracic surgery. Methods: This retrospective study was conducted at Almoosa Specialist Hospital, Saudi Arabia, from August 2016 to August 2019 and included 108 patients who underwent thoracic surgery during the study period. Demographic data, ARISCAT risk index score, length of hospital stay, time of chest tube removal, postoperative complications, and time of discharge were recorded. Results: The study involved 108 patients who met the inclusion criteria. Their mean age was 42.5 ± 18.9 years, and most of them were men (67.6%). Comorbid diseases were present in 53.7%, including mainly type 2 diabetes mellitus and hypertension. FEV1% was measured in 58 patients, with a mean of 71.1 ± 7.3%. The mean ARISCAT score was 39.3 ± 12.4 and ranged from 24 to 76, with more than one-third (35.2%) having a high score grade. The most common surgical procedures were thoracotomy in 47.2%, video-assisted thoracoscopic surgery (VATS) in 28.7%, and mediastinoscopy in 17.6%. Postoperative pulmonary complications (PPCs) occurred in 22 patients (20.4%), mainly pneumonia and atelectasis (9.2%). PPCs occurred most frequently during thoracotomy (68.2%), followed by VATS (13.6%), and mediastinoscopy (9.1%). Multinomial logistic regression of significant risk factors showed that lower FEV1% (OR = 0.88 [0.79-0.98]; p=0.017), longer ICU length of stay (OR = 1.53 [1.04-2.25]; p=0.033), a higher ARISCAT score (OR = 1.22 [1.02-1.47]; p=0.040), and a high ARISCAT grade (OR = 2.77 [1.06-7.21]; p=0.037) were significant predictors of the occurrence of postoperative complications. Conclusion: ARISCAT scoring system, lower FEV1% score, and longer ICU stay were significant predictors of postoperative complications. In addition, thoracotomy was also found to be associated with PPCs.

A combined inactivated cholera and hepatitis A vaccine-induced potent protective immunity in a mouse model.

Cholera and hepatitis A are serious infections spread by consuming contaminated food or water. Vaccination is the most effective strategy to prevent them. Inactivated vaccines are available for both diseases. Our goal in this study is to evaluate the immunogenic response of hepatitis A and cholera combination vaccines compared to the separate vaccines. Hepatitis A and cholera vaccine formulations with and without adjuvants (alum or chitosan) were developed and injected into mice intraperitoneally. We measured the rate of seroconversion; serum-specific antibody titers; lymphoproliferation analysis; cytokine secretions for IL2, IL4, IL10, and IFN-; and a challenge test against cholera strains in the vaccinated mice. Based on the results, the combined vaccination formulation, whether adjuvanted or not, significantly boosted the immune response on both humoral and cellular levels against both hepatitis A and cholera antigens compared to the individual vaccines. These findings validated an important concept for developing an effective combined cholera and hepatitis A vaccine that could be introduced as a novel combined vaccine for travelers as part of a standard immunization schedule. KEY POINTS: • Cholera and hepatitis A combined vaccines (with or without adjuvants) were prepared. • The vaccines were injected into mice groups for humoral and cellular immunity evaluation. • Combined vaccines gave substantial protection against both immunogens.

The Specific Capsule Depolymerase of Phage PMK34 Sensitizes Acinetobacter baumannii to Serum Killing.

The rising antimicrobial resistance is particularly alarming for Acinetobacter baumannii, calling for the discovery and evaluation of alternatives to treat A. baumannii infections. Some bacteriophages produce a structural protein that depolymerizes capsular exopolysaccharide. Such purified depolymerases are considered as novel antivirulence compounds. We identified and characterized a depolymerase (DpoMK34) from Acinetobacter phage vB_AbaP_PMK34 active against the clinical isolate A. baumannii MK34. In silico analysis reveals a modular protein displaying a conserved N-terminal domain for anchoring to the phage tail, and variable central and C-terminal domains for enzymatic activity and specificity. AlphaFold-Multimer predicts a trimeric protein adopting an elongated structure due to a long α-helix, an enzymatic ß-helix domain and a hypervariable 4 amino acid hotspot in the most ultimate loop of the C-terminal domain. In contrast to the tail fiber of phage T3, this hypervariable hotspot appears unrelated with the primary receptor. The functional characterization of DpoMK34 revealed a mesophilic enzyme active up to 50 °C across a wide pH range (4 to 11) and specific for the capsule of A. baumannii MK34. Enzymatic degradation of the A. baumannii MK34 capsule causes a significant drop in phage adsorption from 95% to 9% after 5 min. Although lacking intrinsic antibacterial activity, DpoMK34 renders A. baumannii MK34 fully susceptible to serum killing in a serum concentration dependent manner. Unlike phage PMK34, DpoMK34 does not easily select for resistant mutants either against PMK34 or itself. In sum, DpoMK34 is a potential antivirulence compound that can be included in a depolymerase cocktail to control difficult to treat A. baumannii infections.

Reviewing a plethora of oxidative-type reactions catalyzed by whole cells of Streptomyces species.

Selective oxidation reactions represent a challenging task for conventional organic chemistry. Whole-cell biocatalysis provides a very convenient, easy to apply method to carry out different selective oxidation reactions including chemo-, regio-, and enantio-selective reactions. Streptomyces species are important biocatalysts as they can catalyze these selective reactions very efficiently owing to the wide diversity of enzymes and enzymatic cascades in their cell niche. In this review, we present and analyze most of the examples reported to date of oxidative reactions catalyzed by Streptomyces species as whole-cell biocatalysts. We discuss 33 different Streptomyces species and strains and the role they play in different oxidative reactions over the past five decades. The oxidative reactions have been classified into seven categories that include: hydroxylation of steroids/non-steroids, asymmetric sulfoxidations, oxidation of aldehydes, multi-step oxidations, oxidative cleavage, and N-oxidations. The role played by Streptomyces species as recombinant hosts catalyzing bio-oxidations has also been highlighted.

Oxidation of 5-hydroxymethylfurfural with a novel aryl alcohol oxidase from Mycobacterium sp. MS1601.

Bio-based 5-hydroxymethylfurfural (HMF) serves as an important platform for several chemicals, among which 2,5-furan dicarboxylic acid (FDCA) has attracted considerable interest as a monomer for the production of polyethylene furanoate (PEF), a potential alternative for fossil-based polyethylene terephthalate (PET). This study is based on the HMF oxidizing activity shown by Mycobacterium sp. MS 1601 cells and investigation of the enzyme catalysing the oxidation. The Mycobacterium whole cells oxidized the HMF to FDCA (60% yield) and hydroxymethyl furan carboxylic acid (HMFCA). A gene encoding a novel bacterial aryl alcohol oxidase, hereinafter MycspAAO, was identified in the genome and was cloned and expressed in Escherichia coli Bl21 (DE3). The purified MycspAAO displayed activity against several alcohols and aldehydes; 3,5 dimethoxy benzyl alcohol (veratryl alcohol) was the best substrate among those tested followed by HMF. 5-Hydroxymethylfurfural was converted to 5-formyl-2-furoic acid (FFCA) via diformyl furan (DFF) with optimal activity at pH 8 and 30-40°C. FDCA formation was observed during long reaction time with low HMF concentration. Mutagenesis of several amino acids shaping the active site and evaluation of the variants showed Y444F to have around 3-fold higher kcat /Km and ~1.7-fold lower Km with HMF.

Comparative evaluation of the humoral immune interaction when BCG and conjugated meningococcal vaccines combined or co-administrated in mice.

BCG and conjugated meningococcal vaccines (cMen) are part of the recommended immunization program for young children (<5 years) in many countries all over the world. However, there was no immunogenicity supportive data to assess the effect of BCG and cMen vaccines when combined or co-administrated. Therefore, we sought to evaluate the antibody response in mice groups when BCG and cMen vaccines were whether in combination, co-administration simultaneously or administration with a 14-day gap interval. Our results showed that cMen either combined with BCG vaccine or co-administrated had a significant negative humoral immune effect on each other. This negative impact was observed also when there were 2 weeks between their administration regardless of the vaccination order. Therefore, our results support that it is preferable to separate the two vaccination for > 14 days at least. But additional studies are needed to explore the cellular-mediate response of the immune intervention as well.

The inhibitory effect of dextranases from Bacillus velezensis and Pseudomonas stutzeri on Streptococcus mutans biofilm.

Background and Objectives: Dental caries is a breakdown of the teeth enamel due to harmful bacteria, lack of oral hygiene, and sugar consumption. The acid-producing bacterium Streptococcus mutans is the leading cause of dental caries. Dextranase is an enzyme that can degrade dextran to low molecular weight fractions, which have many therapeutic and industrial applications. The purpose of the present study was to isolate a novel dextranase-producing bacteria from a source (molasses). The cell-free extracts containing dextranases were tested as antibiofilm agents. Materials and Methods: Dextranase-producing bacteria were identified using phenotypic and genotypic methods such as 16S rRNA gene sequencing and enzymatic characterization. Results: The highest six dextranase-producing bacterial isolates were Bacillus species. The best conditions for dextranase productivity were obtained after 72 hours of culture time at pH 7. The addition of glucose to the medium enhanced the production of the enzymes. The cell-free extract of the six most active isolates showed remarkable activity against biofilm formation by Streptococcus mutans ATCC 25175. The highest inhibition activities reached 60% and 80% for Bacillus velezensis and Pseudomonas stutzeri, respectively. Conclusion: Therefore, our study added to the current dextranase-producing bacteria with potential as a source of dextranases.

Engineering a Lysin with Intrinsic Antibacterial Activity (LysMK34) by Cecropin A Fusion Enhances Its Antibacterial Properties against Acinetobacter baumannii.

Bacteriophage-encoded lysins are increasingly reported as alternatives to combat Acinetobacter baumannii infections, for which limited therapeutic options are available. Some lysins, such as LysMK34, have a C-terminal amphipathic helix allowing them to penetrate the otherwise-impermeable outer membrane barrier. Another approach to kill Gram-negative pathogens with lysins relies on fusion of a peptide with outer membrane-permeabilizing properties to the lysin. In this work, we aimed to leverage the intrinsic antibacterial activity of LysMK34 by fusing the peptide cecropin A to its N terminus via a linker of three Ala-Gly repeats, resulting in engineered LysMK34 (eLysMK34). The engineered lysin has an improved antibacterial activity compared to that of the parental lysin, LysMK34, in terms of MICs (0.45 to 1.2 µM), killing rate, and killing extent. eLysMK34 has a ≥2-fold-increased activity against stationary-phase cells, and the bactericidal effect becomes less dependent on the intracellular osmotic pressure. In particular, colistin-resistant strains become highly susceptible to eLysMK34, and enhanced antibacterial activity is observed in complement-deactivated human serum. These observations demonstrate that fusion of a lysin with intrinsic antibacterial activity with a selected outer membrane-permeabilizing peptide is a useful strategy to further improve the in vitro antibacterial properties of such lysins. IMPORTANCE Phage lysins are a new class of enzyme-based antibiotics that increasingly gain interest. Lysins kill cells through rapid degradation of the peptidoglycan layer, resulting in sudden osmotic lysis. Whereas Gram-positive bacteria are readily susceptible to the actions of lysins, Gram-negative bacteria are naturally resistant, as the outer membrane protects their peptidoglycan layer. This work reveals that fusing an outer membrane-permeabilizing peptide to a lysin with intrinsic antibacterial activity results in a superior lysin that shows improved robustness in its antibacterial activity, including against the most worrisome colistin-resistant A. baumannii strains.

Microbial etiologies of ventilator-associated pneumonia (VAP) in intensive care unit of Beni-Suef University's Hospital.

BACKGROUND: Ventilator-associated pneumonia (VAP) is a major health problem for people intubated in intensive care units (ICUs), leading to increased mortality rates, hospital stay, and treatment costs. In the present study, the core pathogens causing VAP in Beni-Suef University's Hospital, Egypt, was investigated over a study period of 2 years (2017-2019). RESULTS: Of a total of 213 patients subjected to mechanical ventilation, 60 have developed VAP during their stay in the ICU. The mortality rate reached 41.7% among VAP patients. Sixty bacteria were isolated from an endotracheal aspirate of hospitalized patients. The different isolates were cultured followed by running biochemical tests, sensitivity assays, and automated VITEK®2 System analysis. Unexpectedly, all the isolates were Gram-negative bacteria. Klebsiella pneumoniae were the main pathogen encountered (27/60 isolates) followed by Acientobacter baumannnii (7/60) and other microorganisms belonging to the genera Moraxella, Escherichia, and Pseudomonas (11/60). Antibiotic sensitivity testing was performed via the VITEK®2 System using up to 16 different antibiotics representing 8 different antibiotic classes and subclasses (aminoglycosides, carbapenems, fluoroquinolones, penicillin/ß-lactamase inhibitor, extended-spectrum cephalosporins, aminopenicillins, aminopenicillins/ß-lactamase inhibitor, folic acid synthesis inhibitor). Majority of the isolates (28/60) showed a remarkable extensive drug resistance (XDR) pattern, while 15 isolates were multi-drug resistant (MDR) and only 6 were pan-drug resistant (PDR) with regard to antibiotics under evaluation. CONCLUSION: The association of VAP with multi-drug-resistant bacteria is alarming, and rapid management is crucial. Identification of core pathogens is essential for identifying the most appropriate technique for infection control.

Cnicin as an Anti-SARS-CoV-2: An Integrated In Silico and In Vitro Approach for the Rapid Identification of Potential COVID-19 Therapeutics.

Since the emergence of the SARS-CoV-2 pandemic in 2019, it has remained a significant global threat, especially with the newly evolved variants. Despite the presence of different COVID-19 vaccines, the discovery of proper antiviral therapeutics is an urgent necessity. Nature is considered as a historical trove for drug discovery, especially in global crises. During our efforts to discover potential anti-SARS CoV-2 natural therapeutics, screening our in-house natural products and plant crude extracts library led to the identification of C. benedictus extract as a promising candidate. To find out the main chemical constituents responsible for the extract's antiviral activity, we utilized recently reported SARS CoV-2 structural information in comprehensive in silico investigations (e.g., ensemble docking and physics-based molecular modeling). As a result, we constructed protein-protein and protein-compound interaction networks that suggest cnicin as the most promising anti-SARS CoV-2 hit that might inhibit viral multi-targets. The subsequent in vitro validation confirmed that cnicin could impede the viral replication of SARS CoV-2 in a dose-dependent manner, with an IC50 value of 1.18 µg/mL. Furthermore, drug-like property calculations strongly recommended cnicin for further in vivo and clinical experiments. The present investigation highlighted natural products as crucial and readily available sources for developing antiviral therapeutics. Additionally, it revealed the key contributions of bioinformatics and computer-aided modeling tools in accelerating the discovery rate of potential therapeutics, particularly in emergency times like the current COVID-19 pandemic.

Chitosan and alginate salt as biomaterials are potential natural adjuvants for killed cholera vaccine.

Chitosan and alginate salts are natural biopolymers that have gained recent attention in the biomedical sectors. Their properties allow them to become potential candidates as safe, cheap, and effective vaccine adjuvants. The present study aimed to enhance the immunogenic response of a current injectable killed cholera vaccine (KCV) using chitosan and alginate salt as natural adjuvants against alum. We tested KCV adjuvanted with alum, chitosan, and sodium alginate in mice. Mice were immunized intraperitoneally with KCV adjuvanted with alum, chitosan, or alginate salt and compared with a control unadjuvanted immunized group. Humoral, cellular, and functional immune responses were evaluated in all groups. The addition of adjuvants, particularly natural adjuvants, to KCV significantly improved the immune response as demonstrated by specific antibody increase, strong proliferation effects, and high protection rate against different challenge doses of cholera strains. Our findings demonstrate that chitosan and alginate salt are superior adjuvants for boosting the KCV immune response and highlights the requirement for further vaccine development.

A metabolomic approach to target antimalarial metabolites in the Artemisia annua fungal endophytes.

Fungal endophytes are a major source of anti-infective agents and other medically relevant compounds. However, their classical blinded-chemical investigation is a challenging process due to their highly complex chemical makeup. Thus, utilizing cheminformatics tools such as metabolomics and computer-aided modelling is of great help deal with such complexity and select the most probable bioactive candidates. In the present study, we have explored the fungal endophytes associated with the well-known antimalarial medicinal plant Artemisia annua for their production of further antimalarial agents. Based on the preliminary antimalarial screening of these endophytes and using LC-HRMS-based metabolomics and multivariate analyses, we suggested different potentially active metabolites (compounds 1-8). Further in silico investigation using the neural-network-based prediction software PASS led to the selection of a group of quinone derivatives (compounds 1-5) as the most possible active hits. Subsequent in vitro validation revealed emodin (1) and physcion (2) to be potent antimalarial candidates with IC50 values of 0.9 and 1.9 µM, respectively. Our approach in the present investigation therefore can be applied as a preliminary evaluation step in the natural products drug discovery, which in turn can facilitate the isolation of selected metabolites notably the biologically active ones.

Prevalence of Multi-drug Resistant Acinetobacter baumannii (MDRAB) in Amman Jordan During 2018.

PURPOSE: Acinetobacter baumannii is an opportunistic pathogen, and is among the most problematic nosocomial infections as well as community-acquired infections. This retrospective study was conducted as an attempt to determine the prevalence of multidrug-resistant A. baumannii (MDRAB) isolates from the north and central Jordan area during 2018. METHODS: Patients' records provided by an accredited central private laboratory located in Amman, were examined for A. baumannii isolates identified during this period. The isolates were identified to the species level using the API-10S system and the antimicrobial sensitivity testing was determined using the Kirby-Bauer disc diffusion method. RESULTS: A total of 43 unduplicated isolates were obtained and classified according to clinical sampling source into: Group I (blood), Group II (urine) and Group III (wound, pus, sputum, bedsore and others). Total MDRAB isolates recorded were 29 (67.4 %). Resistance to imipenem was found to be 36% and 94% among groups II and III, respectively, and resistance to meropenem was 60% and 88% among the same groups, respectively. CONCLUSION: Antimicrobial stewardship programs at a national scale are needed to calculate the actual proportion of MDRAB in the country and to combat its increasing emergence and decrease the magnitude of antibiotic resistance.

Heterologous expression of lytic polysaccharide monooxygenases (LPMOs).

Lytic polysaccharide monooxygenases (LPMOs) are relatively new enzymes that have been discovered 10 years ago. LPMOs comprise a diverse group of enzymes which play a pivotal role in the depolymerization of sugar-based biopolymers including cellulose, hemicellulose, chitin, and starch. Their mechanism of action relies on the correct coordination of a copper ion in the active site, which is partly composed of the N-terminal histidine. Therefore, correct secretion and folding of these copper-enzymes is fundamental for obtaining a catalytic activity. LPMOs occur in all kingdoms of life; they have been found in viruses, bacteria and eukaryotes, including fungi, plants and animals. In many cases, using homologous expression of these proteins is not feasible and an alternative organism, which can be cultured and is able to heterologously express the protein of interest, is required for studying enzyme properties. Therefore, we made an extensive compilation of expression techniques used for LPMOs the expression and characterization of which have been reported to date. In the current review, we provide a summary of the different techniques, including expression hosts and vectors, secretion methods, and culturing conditions, that have been used for the overexpression and production of this important class of enzymes at laboratory scale. Herein, we compare these techniques and assess their advantages and disadvantages.

Lysin LysMK34 of Acinetobacter baumannii Bacteriophage PMK34 Has a Turgor Pressure-Dependent Intrinsic Antibacterial Activity and Reverts Colistin Resistance.

The prevalence of extensively and pandrug-resistant strains of Acinetobacter baumannii leaves little or no therapeutic options for treatment for this bacterial pathogen. Bacteriophages and their lysins represent attractive alternative antibacterial strategies in this regard. We used the extensively drug-resistant A. baumannii strain MK34 to isolate the bacteriophage PMK34 (vB_AbaP_PMK34). This phage shows fast adsorption and lacks virulence genes; nonetheless, its narrow host spectrum based on capsule recognition limits broad application. PMK34 is a Fri1virus member of the Autographiviridae and has a 41.8-kb genome (50 open reading frames), encoding an endolysin (LysMK34) with potent muralytic activity (1,499.9 ± 131 U/µM), a typical mesophilic thermal stability up to 55°C, and a broad pH activity range (4 to 10). LysMK34 has an intrinsic antibacterial activity up to 4.8 and 2.4 log units for A. baumannii and Pseudomonas aeruginosa strains, respectively, but only when a high turgor pressure is present. The addition of 0.5 mM EDTA or application of an osmotic shock after treatment can compensate for the lack of a high turgor pressure. The combination of LysMK34 and colistin results in up to 32-fold reduction of the MIC of colistin, and colistin-resistant strains are resensitized in both Mueller-Hinton broth and 50% human serum. As such, LysMK34 may be used to safeguard the applicability of colistin as a last-resort antibiotic.IMPORTANCEA. baumannii is one of the most challenging pathogens for which development of new and effective antimicrobials is urgently needed. Colistin is a last-resort antibiotic, and even colistin-resistant A. baumannii strains exist. Here, we present a lysin that sensitizes A. baumannii for colistin and can revert colistin resistance to colistin susceptibility. The lysin also shows a strong, turgor pressure-dependent intrinsic antibacterial activity, providing new insights in the mode of action of lysins with intrinsic activity against Gram-negative bacteria.

Actinomycetes from the Red Sea Sponge Coscinoderma mathewsi: Isolation, Diversity, and Potential for Bioactive Compounds Discovery.

The diversity of actinomycetes associated with the marine sponge Coscinoderma mathewsi collected from Hurghada (Egypt) was studied. Twenty-three actinomycetes were separated and identified based on the 16S rDNA gene sequence analysis. Out of them, three isolates were classified as novel species of the genera Micromonospora, Nocardia, and Gordonia. Genome sequencing of actinomycete strains has revealed many silent biosynthetic gene clusters and has shown their exceptional capacity for the production of secondary metabolites, not observed under classical cultivation conditions. Therefore, the effect of mycolic-acid-containing bacteria or mycolic acid on the biosynthesis of cryptic natural products was investigated. Sponge-derived actinomycete Micromonospora sp. UA17 was co-cultured using liquid fermentation with two mycolic acid-containing actinomycetes (Gordonia sp. UA19 and Nocardia sp. UA 23), or supplemented with pure mycolic acid. LC-HRESIMS data were analyzed to compare natural production across all crude extracts. Micromonospora sp. UA17 was rich with isotetracenone, indolocarbazole, and anthracycline analogs. Some co-culture extracts showed metabolites such as a chlorocardicin, neocopiamycin A, and chicamycin B that were not found in the respective monocultures, suggesting a mycolic acid effect on the induction of cryptic natural product biosynthetic pathways. The antibacterial, antifungal, and antiparasitic activities for the different cultures extracts were also tested.

Alginate-coated chitosan nanoparticles act as effective adjuvant for hepatitis A vaccine in mice.

The numerous recent hepatitis A outbreaks emphasize the need for vaccination; despite the effectiveness of the current ones, developments are needed to overcome its high cost plus some immune response limitations. Our study aims to evaluate the use of chitosan and alginate-coated chitosan nanoparticles as an adjuvant/carrier for the hepatitis A vaccine (HAV) against the traditional adjuvant alum. Immune responses towards (HAV-Al) with alum, (HAV-Ch) with chitosan, and (HAV-aCNP) with alginate-coated chitosan nanoparticles, were assessed in mice. HAV-aCNP significantly improved the immunogenicity by increasing the seroconversion rate (100%), the hepatitis A antibodies level, and the splenocytes proliferation. Thus, the HAV-aCNP adjuvant was superior to other classes in IFN-γ and IL-10 development. Meanwhile, the solution formula of HAV with chitosan showed comparable humoral and cellular immune responses to alum-adjuvanted suspension with a balanced Th1/Th2 immune pathway. The current study showed the potential of alginate-coated chitosan nanoparticles as an effective carrier for HAV. Consequently, this would impact the cost of HAV production positively.

Enantioselective sulfoxidation using Streptomyces glaucescens GLA.0.

Asymmetric oxidation of prochiral sulfides is a direct means for production of enantiopure sulfoxides which are important in organic synthesis and the pharmaceutical industry. In the present study, Streptomyces glaucescens GLA.0 was employed for stereoselective oxidation of prochiral sulfides. Growing cells selectively catalyzed the oxidation of phenyl methyl sulfide to the corresponding sulfoxide. Only very little overoxidation was observed, resulting in minor amounts of the unwanted sulfone. Addition of isopropyl alcohol as a co-solvent, time of substrate addition and composition of the reaction media resulted in enhanced phenyl methyl sulfide biotransformation. The concentration of the undesired by-product (sulfone) was as low as 4% through the reaction course under optimal reaction conditions. The results show that S. glaucescens GLA.0 is a promising whole-cell biocatalyst for preparing highly enantiopure (R)-phenyl methyl sulfoxide in high yield (90%) with an enantiomeric excess (ee) exceeding 99%.

Biocementation of soil by calcite/aragonite precipitation using Pseudomonas azotoformans and Citrobacter freundii derived enzymes.

Microbial geotechnology is the use of microorganisms and/or their derivatives to alter engineering properties of soil for improving its stability, strength and stiffness. Ureases hydrolyze urea in the soil leading to CaCO3 precipitation, which binds soil particles together (biocementation). In the present study, nine Egyptian soils were screened for urease-producing bacteria, 15 isolates were obtained, and optimum urease producers were identified. Growth kinetics were measured at different pH values and in the presence of molasses as the sole carbon source. Citrobacter freundii and Pseudomonas azotoformans showed the highest extracellular urease activities of 45.5 ± 3.4 and 54.9 ± 3.5 U ml-1, respectively. Cell-free supernatants of these isolates mediated the precipitation of CaCO3 from the cementation solution (urea and CaCl2). The X-ray diffraction (XRD) of the precipitates revealed the formation of calcite and aragonite crystal forms. Sandy soil treated with the supernatants and evaluated by modified proctor and California bearing ratio (CBR) tests had significantly higher (P < 0.05) soil strength (CBR = ∼40% versus 30% for untreated soil). Scanning electron microscopy showed the CaCO3 precipitation resulting in reduction of the gaps between soil particles, hence confirming the biocementation phenomenon which is responsible for soil stabilization and the desired repairing effect on cracks. The use of urease-containing cell-free supernatant rather than the whole microorganism in biocementation lowers the risks of spreading pathogens to the environment and altering the microbial diversity at the application area.