Protein-based microneedles for biomedical applications: A systematic review.

Microneedles are minimally-invasive devices with the unique capability of bypassing physiological barriers. Hence, they are widely used for different applications from drug/vaccine delivery to diagnosis and cosmetic fields. Recently, natural biopolymers (particularly carbohydrates and proteins) have garnered attention as safe and biocompatible materials with tailorable features for microneedle construction. Several review articles have dealt with carbohydrate-based microneedles. This review aims to highlight the less-noticed role of proteins through a systematic search strategy based on the PRISMA guideline from international databases of PubMed, Science Direct, Scopus, and Google Scholar. Original English articles with the keyword "microneedle(s)" in their titles along with at least one of the keywords "biopolymers, silk, gelatin, collagen, zein, keratin, fish-scale, mussel, and suckerin" were collected and those in which the proteins undertook a structural role were screened. Then, we focused on the structures and applications of protein-based microneedles. Also, the unique features of some protein biopolymers that make them ideal for microneedle construction (e.g., excellent mechanical strength, self-adhesion, and self-assembly), as well as the challenges associated with them were reviewed. Altogether, the proteins identified so far seem not only promising for the fabrication of "better" microneedles in the future but also inspiring for designing biomimetic structural biopolymers with ideal characteristics.

Comprehensive network of stress-induced responses in Zymomonas mobilis during bioethanol production: from physiological and molecular responses to the effects of system metabolic engineering.

Nowadays, biofuels, especially bioethanol, are becoming increasingly popular as an alternative to fossil fuels. Zymomonas mobilis is a desirable species for bioethanol production due to its unique characteristics, such as low biomass production and high-rate glucose metabolism. However, several factors can interfere with the fermentation process and hinder microbial activity, including lignocellulosic hydrolysate inhibitors, high temperatures, an osmotic environment, and high ethanol concentration. Overcoming these limitations is critical for effective bioethanol production. In this review, the stress response mechanisms of Z. mobilis are discussed in comparison to other ethanol-producing microbes. The mechanism of stress response is divided into physiological (changes in growth, metabolism, intracellular components, and cell membrane structures) and molecular (up and down-regulation of specific genes and elements of the regulatory system and their role in expression of specific proteins and control of metabolic fluxes) changes. Systemic metabolic engineering approaches, such as gene manipulation, overexpression, and silencing, are successful methods for building new metabolic pathways. Therefore, this review discusses systems metabolic engineering in conjunction with systems biology and synthetic biology as an important method for developing new strains with an effective response mechanism to fermentation stresses during bioethanol production. Overall, understanding the stress response mechanisms of Z. mobilis can lead to more efficient and effective bioethanol production.

Assessing the efficiency and microbial diversity of H2S-removing biotrickling filters at various pH conditions.

This study aimed to investigate the operation of three parallel biotrickling filters (BTFs) in removing H2S at different pH conditions (haloalkaliphilic, neutrophilic, and acidophilic) and their associated microbial population in the biodesulfurization process. BTF columns were inoculated with enriched inoculum and experiments were performed by gradually reducing Empty Bed Retention Time (EBRT) and increasing inlet concentration in which the maximum removal efficiency and maximum elimination capacity in EBRT 60 s reached their maximum level in haloalkaline condition (91% and 179.5 g S-H2S m-3 h-1). For visualizing the attached microbial biofilms on pall rings, Scanning Electron Microscopy (SEM) was used and microbial community structure analysis by NGS showed that the most abundant phyla in haBTF, nBTF, and aBTF belong to Gammaproteobacteria, Betaproteobacteria, and Acidithiobacillia, respectively. Shannon and Simpson indexes evaluation showed a lower diversity of bacteria in the aBTF reactor than that of nBTF and haBTF and beta analysis indicated a different composition of bacteria in haBTF compared to the other two filters. These results indicated that the proper performance of BTF under haloalkaliphilic conditions is the most effective way for H2S removal from air pollutants of different industries.

Fungal-bacterial consortia: A promising strategy for the removal of petroleum hydrocarbons.

Nowadays, petroleum hydrocarbon pollution is one of the most widespread types of contamination that poses a serious threat to both public health and the environment. Among various physicochemical methods, bioremediation is an eco-friendly and cost-effective way to eliminate petroleum hydrocarbon pollutants. The successful degradation of all hydrocarbon components and the achievement of optimal efficiency are necessary for the success of this process. Using potential microbial consortia with rich metabolic networks is a promising strategy for addressing these challenges. Mixed microbial communities, comprising both fungi and bacteria, exhibit diverse synergistic mechanisms to degrade complex hydrocarbon contaminants, including the dissemination of bacteria by fungal hyphae, enhancement of enzyme and secondary metabolites production, and co-metabolism of pollutants. Compared to pure cultures or consortia of either fungi or bacteria, different studies have shown increased bioremediation of particular contaminants when combined fungal-bacterial treatments are applied. However, antagonistic interactions, like microbial competition, and the production of inhibitors or toxins can observed between members. Furthermore, optimizing environmental factors (pH, temperature, moisture, and initial contaminant concentration) is essential for consortium performance. With the advancements in synthetic biology and gene editing tools, it is now feasible to design stable and robust artificial microbial consortia systems. This review presents an overview of using microbial communities for the removal of petroleum pollutants by focusing on microbial degradation pathways, and their interactions. It also highlights the new strategies for constructing optimal microbial consortia, as well as the challenges currently faced and future perspectives of applying fungal-bacterial communities for bioremediation.

Increasing the production of the bioactive compounds in medicinal mushrooms: an omics perspective.

Macroscopic fungi, mainly higher basidiomycetes and some ascomycetes, are considered medicinal mushrooms and have long been used in different areas due to their pharmaceutically/nutritionally valuable bioactive compounds. However, the low production of these bioactive metabolites considerably limits the utilization of medicinal mushrooms both in commerce and clinical trials. As a result, many attempts, ranging from conventional methods to novel approaches, have been made to improve their production. The novel strategies include conducting omics investigations, constructing genome-scale metabolic models, and metabolic engineering. So far, genomics and the combined use of different omics studies are the most utilized omics analyses in medicinal mushroom research (both with 31% contribution), while metabolomics (with 4% contribution) is the least. This article is the first attempt for reviewing omics investigations in medicinal mushrooms with the ultimate aim of bioactive compound overproduction. In this regard, the role of these studies and systems biology in elucidating biosynthetic pathways of bioactive compounds and their contribution to metabolic engineering will be highlighted. Also, limitations of omics investigations and strategies for overcoming them will be provided in order to facilitate the overproduction of valuable bioactive metabolites in these valuable organisms.

Simultaneous bioreduction of tellurite and selenite by Yarrowia lipolytica, Trichosporon cutaneum, and their co-culture along with characterization of biosynthesized Te-Se nanoparticles.

BACKGROUND: Natural and anthropogenic activities, such as weathering of rocks and industrial processes, result in the release of toxic oxyanions such as selenium (Se) and tellurium (Te) into the environment. Due to the high toxicity of these compounds, their removal from the environment is vital. RESULTS: In this study, two yeast strains, Yarrowia lipolytica and Trichosporon cutaneum, were selected as the superior strains for the bioremediation of tellurium and selenium. The reduction analyses showed that exposure to selenite induced more detrimental effects on the strains compared to tellurite. In addition, co-reduction of pollutants displayed almost the same results in selenite reduction and more than ~ 20% higher tellurite reduction in 50 h, which shows that selenite triggered higher tellurite reduction in both strains. The selenite and tellurite kinetics of removal were consistent with the first-order model because of their inhibitory behavior. The result of several characterization experiments, such as FE-SEM (Field emission scanning electron microscopy), dynamic light scattering (DLS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), and dispersive X-ray (EDX) on Te-Se nanoparticles (NPs) revealed that the separated Te-Se NPs were needle-like, spherical, and amorphous, consisted of Te-Se NPs ranging from 25 to 171 nm in size, and their surface was covered with different biomolecules. CONCLUSIONS: Remarkably, this work shows, for the first time, the simultaneous bioreduction of tellurite and selenite and the production of Te-Se NPs using yeast strains, indicating their potential in this area, which may be applied to the nanotechnology industry and environmental remediation.

Effect of Fe and Al based coagulants and disinfectants on polyethylene microplastics removal in coagulation process through response surface methodology.

Microplastic (MP) pollution has been rising as a threatening risk and recently has appealed to the attention of more researchers. In this study, influential parameters affecting the removal rate of polyethylene microplastics (PEMPs) were optimized through response surface methodology (RSM). In Box Behnken Design (BBD), independent parameters were pH, PEMP size, coagulant dosage and polyacrylamide dosage. Two experimental sets were conducted, one with ferric chloride and the second with poly aluminum chloride as two commonly applied coagulants in drinking water treatment plants (DWTPs). Comparing the results of optimized parameters, PAC was a better coagulant with the predicted removal rate of 58.19%, while the removal rate with ferric chloride as a coagulant was predicted to be 56.37%. Moreover, some experiments were conducted to analyze the effect of ozone gas and sodium hypochlorite as disinfectants on removal rate. The highest removal rate was observed when 2 ppm of O3 was added to the solution coagulated with optimal dosage of PAC, reaching the removal rate of 76.8%.

Investigating biodegradation of polyethylene and polypropylene microplastics in Tehran DWTPs.

Microplastic (MP) pollution is a growing concern and various methods are being sought to alleviate the level of pollution worldwide. This study investigates the biodegradation capacity of MPs by indigenous microorganisms of raw water from Tehran drinking water treatment plants. By exposing polypropylene (PP) and polyethylene (PE) MPs to selected microbial colonies, structural, morphological, and chemical changes were detected by scanning electron microscope (SEM), cell weight measurement, Fourier transform infrared (FTIR), Raman spectroscopy test, and thermal gravimetric analysis (TGA). Selected bacterial strains include Pseudomonas protegens strain (A), Bacillus cereus strain (B), and Pseudomonas protegens strain (C). SEM analysis showed roughness and cracks on PP MPs exposed to strains A and C. However, PE MPs exposed to strain B faced limited degradation. In samples related to strain A, the Raman spectrum was completely changed, and a new chemical structure was created. Both TGA and FTIR analysis confirmed changes detected by Raman analysis of PP and PE MPs in chemical changes in this study. The results of cell dry weight loss for microbial strains A, B, and C were 13.5, 38.6, and 25.6%, respectively. Moreover, MPs weight loss was recorded at 32.6% for PP MPs with strain A, 13.3% for PE MPs with strain B, and 25.6% for PP MPs with strain C.

Post-Weaning Treatment with Probiotic Inhibited Stress-Induced Amnesia in Adulthood Rats: The Mediation of GABAergic System and BDNF/c-Fos Signaling Pathways.

The current study aimed to examine the effect of post-weaning treatment with probiotics on memory formation under stress during the adult period in male Wistar rats. Considering GABA is a potential mediator between probiotics and the host, the present study also investigated the involvement of the GABAergic system in the probiotic response. The hippocampal and prefrontal cortical (PFC) expression levels of BDNF and c-Fos were also assessed to show whether the treatments affect the memory-related signaling pathway. Three weeks after birth, the post-weaning rats were fed with probiotic water (PW) or tap water (TW) for 2, 3, 4, or 5 weeks. Exposure to acute stress impaired memory formation in a passive avoidance learning task. Feeding the post-weaning animals with probiotic strains (3, 4, or 5 weeks) inhibited stress-induced amnesia of the adult period. Post-training intracerebroventricular (ICV) microinjection of muscimol improved stress-induced amnesia in the animals fed with TW. ICV microinjection of muscimol inhibited probiotic treatment's significant effect on the stress response in the memory task. The expression levels of BDNF and c-Fos in the PFC and the hippocampus were significantly decreased in the stress animal group. The levels of BDNF and c-Fos were increased in the PW/stress animal group. The muscimol response was compounded with the decreased levels of BDNF and c-Fos in the PFC and the hippocampus. Thus, the GABA-A receptor mechanism may mediate the inhibitory effect of this probiotic mixture on stress-induced amnesia, which may be associated with the PFC and hippocampal BDNF/c-Fos signaling changes.

Development and evaluation of a novel methotrexate-loaded electrospun patch to alleviate psoriasis plaques.

OBJECTIVE: To achieve an effective topical formulation of Methotrexate (MTX) as a first-line treatment of psoriasis, we formulated three MTX-loaded electrospun nanofibrous patches composed of polycaprolactone (PCL), Eudragit L100, and a mixture of them. SIGNIFICANCE: Topical delivery of MTX provides an appropriate therapeutic performance while circumventing the life-threatening side effects of systemic administration. METHODS: Three MTX-loaded electrospun nanofibrous patches were prepared and characterized in terms of size and morphology (using SEM), thermal behavior (by TGA and DSC), and crystalline structure (using XRD). Furthermore, the wettability and mechanical strength of samples were investigated through water contact angle and tensile strength tests. Also, the encapsulation efficiency of MTX was calculated. Subsequently, in vitro drug release profile of each formulation was obtained and different kinetic models were fitted to achieve the best-matched model. Accordingly, the ex vivo skin permeation of MTX was studied for the optimum formulation. RESULTS: All samples showed appropriate morphology, thermal behavior, and encapsulation efficiency. Also, XRD results showed that MTX is dispersed within the polymeric matrices in the amorphous state (with no crystalline region). Release studies demonstrated that MTX-loaded Eudragit L100-PCL formulation outperformed in terms of mechanical behavior and in vitro drug release. This formulation also exhibited better skin permeation. CONCLUSION: The obtained controlled-release MTX-loaded electrospun patches seem promising to provide a long-acting topical treatment of psoriatic plaques with minimized systemic side effects.

Skin permeability, a dismissed necessity for anti-wrinkle peptide performance.

BACKGROUND: The skin offers various benefits and potential for peptide delivery if its barrier performance can be reduced temporarily and reversibly. As peptides possess high molecular weight, hydrophilic nature (in most cases), and ionizable groups in the structure, their skin delivery is highly challenging. Apart from this, they are susceptible to the proteolytic enzymes in the skin. Anti-wrinkle peptides, like other peptides, suffer from insufficient skin permeability, while most of them must penetrate deep in the skin to present their efficacy. Although the cellular studies indicate the effectiveness of such peptides, without the ability to permeate the skin sufficiently, this efficacy is useless. Poor skin permeability of anti-wrinkle peptides has led to ongoing research for finding feasible and noninvasive enhancement methods that would be desirable for consumers of cosmetic products. METHOD: In this paper, the possibility of skin permeation of anti-wrinkle peptides as well as the chemical, physical, and encapsulation approaches that have been employed to date to increase permeability of these difficult molecules are thoroughly reviewed. RESULTS: Most anti-wrinkle peptides are not appropriate candidates for skin permeation and the use of enhancement methods is essential to increase their permeability. To do so, only some permeability enhancement approaches have been applied so far, including chemical modification with hydrophobic moieties or cell penetrating peptides, metal complexation, chemical permeation enhancers, iontophoresis, microneedles, and encapsulation in nanocarriers. The results of studies published on the skin permeability of anti-wrinkle peptides carnosine, GHK, PKEK, GEKG, GQPR, and KTTKS indicate that the skin permeability of these peptides can be successfully increased. CONCLUSION: Although the skin permeability of most anti-wrinkle peptides is not high enough and most anti-wrinkle peptides might not reach their targets in the skin at right concentrations, their permeability can be increased to therapeutic concentrations using various enhancement approaches.

CONTEXTE: La peau offre divers avantages et a la faculté de recevoir des peptides si l'on parvient à réduire temporairement et de manière réversible sa capacité à fonctionner comme une barrière. Comme les peptides ont un poids moléculaire élevé, une nature hydrophile (dans la plupart des cas) et possèdent des groupes ionisables dans leur structure, il est très difficile d'en faire bénéficier la peau. En outre, ils sont sensibles aux enzymes protéolytiques de la peau. Les peptides antirides, comme d'autres peptides, souffrent d'une capacité insuffisante de perméation de la peau ; or, la plupart d'entre eux doivent y pénétrer profondément pour avoir une efficacité. Bien que les études cellulaires indiquent l'efficacité de ces peptides, s'ils sont incapables de pénétrer suffisamment la peau, cette efficacité est inopérante. Face à cette perméabilité médiocre de la peau aux peptides antirides, des recherches sont menées actuellement pour trouver des méthodes d'amélioration à la fois réalisables et non invasives, qui soient attractives pour les consommateurs de produits cosmétiques. MÉTHODE: Dans cet article, nous étudions de manière approfondie la possibilité de perméation des peptides antirides à travers l'épiderme, ainsi que les approches chimiques, physiques et d'encapsulation utilisées à ce jour pour augmenter l'aptitude à la perméation de ces molécules difficiles. RÉSULTATS: La plupart des peptides antirides ne sont pas de bons candidats à la perméation de l'épiderme, et il est essentiel d'avoir recours à des méthodes de renforcement pour augmenter leur capacité de pénétration. Pour ce faire, seules certaines approches de renforcement de la perméation ont été appliquées jusqu'à présent : une modification chimique avec des fractions hydrophobes ou des peptides pénétrants la cellule ; la complexation métallique ; les amplificateurs de perméation chimique ; l'iontophorèse ; les micro-aiguilles et l'encapsulation dans les nano supports. Les résultats des études publiées sur la perméabilité de l'épiderme aux peptides antirides que sont la carnosine, le GHK, le PKEK, le GEKG, le GQPR et le KTTKS indiquent que l'augmentation de la capacité de perméation de l'épiderme de ces peptides est possible et donne de bons résultats. CONCLUSION: Bien que la capacité de perméation de la plupart des peptides antirides ne soit pas suffisamment élevée et qu'ils n'atteignent pas leurs cibles dans la peau aux bonnes concentrations, cette capacité peut être augmentée jusqu'à des concentrations thérapeutiques en recourant à diverses approches de renforcement.

RAB5A is associated with genes involved in exosome secretion: Integration of bioinformatics analysis and experimental validation.

Exosomes, as cell-cell communicators with an endosomal origin, are involved in the progression of various diseases. RAB5A, a member of the small Rab GTPases family, which is well known as a key regulator of cellular endocytosis, is expected to be involved in exosome secretion. Here, we found the impact of RAB5A on exosome secretion from human hepatocellular carcinoma cell line using a rapid yet reliable bioinformatics approach followed by experimental analysis. Initially, RAB5A and exosome secretion-related genes were gathered from bioinformatics tools, namely, CTD, COREMINE, and GeneMANIA; and published papers. Protein-protein interaction (PPI) was then constructed by the Search Tool for Retrieval of Interacting Genes (STRING) database. Among them, several genes with different combined scores were validated by the real-time quantitative polymerase chain reaction (RT-qPCR) in stable RAB5A knockdown cells. Thereafter, to validate the bioinformatics results functionally, the impact of RAB5A knockdown on exosome secretion was evaluated. Bioinformatics analysis showed that RAB5A interacts with 37 genes involved in exosome secretion regulatory pathways. Validation by RT-qPCR confirmed the association of RAB5A with candidate interacted genes and interestingly showed that even medium to low combined scores of the STRING database could be experimentally valid. Moreover, the functional analysis demonstrated that the stable silencing of RAB5A could experimentally decrease exosome secretion. In conclusion, we suggest RAB5A as a regulator of exosome secretion based on our bioinformatics approach and experimental analysis. Also, we propose the usage of PPI-derived from the STRING database regardless of their combined scores in advanced bioinformatics analysis.

RAB5A effect on metastasis of hepatocellular carcinoma cell line via altering the pro-invasive content of exosomes.

Tumor microenvironment exerts a critical role in cancer progression and metastasis. Exosomes, cell-cell communicators and major players of the tumor microenvironment are considered as a serious mediator of cancer metastasis. Here, we determined the effect of RAB5A gene on the hepatocellular carcinoma (HCC) cells particularly whether RAB5A could affect HCC metastasis via regulating the pro-invasive content of exosomes. In response to RAB5A knockdown, we analyzed the proliferation rate and migration capability of HCC cells. Then, we estimated changes in the total protein composition of exosomes via analyzing the expression of exosomal markers, CD63 and Alix. Thereafter, alterations of the pro-invasive content of exosomes were functionally evaluated using matrigel invasion assay. Our results revealed that knockdown of RAB5A could decrease HCC cell proliferation rate and migration capability significantly. Moreover, no significant changes in the expression of exosomal CD63 and Alix reflected that no differences might be occurred in protein composition of RAB5A knockdown cell-derived exosomes. Matrigel invasion assay functionally showed that exosomes-derived from RAB5A knockdown cells still had pro-invasive properties and their pro-invasive content was not affected in response to RAB5A knockdown. In conclusion, we believe that our results propose a new explanation about RAB5A and metastatic potentials of exosomes-derived from HCC cells.

Release behavior, mechanical properties, and antibacterial activity of ciprofloxacin-loaded acrylic bone cement: a mechanistic study.

OBJECTIVE: To evaluate the effect of ciprofloxacin concentration and cement geometry on release, mechanical, and antibacterial properties of PMMA bone cement. Significance: Cements are used in different geometries and drug concentrations. These can affect cement strength, drug release behavior, and its antibacterial activity. METHODS: Antibiotic-loaded bone cement (ALBC) containing 2.5, 5.0, and 10.0 wt% ciprofloxacin were prepared as slab, rectangular prism and short cylinder. Drug release and compression strength of the cements were investigated for 28 days at 37 °C. The ALBC efficacies against prevalent bone infection bacteria, S. aureus, E. coli, and P. aeruginosa, were investigated. Drug determination was by HPLC. RESULTS: A two-stage behavior of fast release through dissolution/diffusion (stage A; <96 h) and 2-5 times slower Fickian diffusion (stage B; 96-672 h) was observed. Significant differences for release rate were observed among different geometries in the order of cylinder > prism > slab, in correlation with systems' thickness, indicating lower drug depletion in thicker systems. Release rates were proportional to concentration for 2.5 and 5% systems. At 10.0% loading, however, apparently interconnected channels and higher porosity reduced the diffusional resistance and provided higher release rates than what expected from concentration increment. Growth of Gram-negative bacteria and S. aureus was inhibited at the lowest dose of drug over 1 and 48 h, respectively. ALBCs with 5.0 and 10.0% ciprofloxacin showed decrease of compression strength to below ISO standard. CONCLUSIONS: Different properties of acrylic cements are affected by geometry and drug concentration and should be considered for optimized drug therapy.

Effect of Palmitic Acid Conjugation on Physicochemical Properties of Peptide KTTKS: A Preformulation Study.

Lys-Thr-Thr-Lys-Ser (KTTKS) minimally crosses the skin because of hydrophilicity; therefore, its palmitoyl derivative, palmitoyl-KTTKS (Pal-KTTKS), is used in cosmetic products. In spite of this, there is insuffi cient information on its physicochemical properties and the effects of palmitoylation on such properties. The aim of this study was to investigate these properties. Such information would help appropriate formulation development. KTTKS and Pal-KTTKS were synthesized and characterized for ultra violet (UV) absorption, structure [X-ray diffraction (XRD)], morphology (electron microscopy), birefringence (polarized light microscopy), partitioning,solubility, thermal behavior (melting, thermogravimetric analysis, and differential scanning calorimetry), surface activity, critical micelle concentration (CMC, by tensiometry), and stability. KTTKS and Pal-KTTKS decomposed at about 154 and 150°C, respectively, and did not show a melting point before decomposition. The maximum UV absorbance of peptides was less than 200 nm. Both peptides showed birefringence, irregular flake morphologies, and hygroscopicity. KTTKS was freely soluble in water at room temperature (logP = -1.6 ± 0.15), indicating its hydrophilic nature. logP of Pal-KTTKS was calculated to be about 3.7, indicating a lipophilic compound. Pal-KTTKS showed surface activity with a CMC value of 0.024 ± 0.004 mM (19.25 ± 2.9 mg/L),whereas KTTKS did not show such surface activity. Palmitoylation demonstrated sharp peaks in the XRD pattern of KTTKS. KTTKS and Pal-KTTKS differ mainly in terms of chemical properties and show some similarity in physical properties. These results can be used for formulation developments.

Blastobotrys persicus sp. nov., an ascomycetous yeast species isolated from cave soil.

Two strains (AHD129-1T and AHD129-2) of a new anamorphic yeast species were isolated from Mejare cave soil samples of Abdanan, Ilam, Iran. Nucleotide divergence in the D1/D2 domain of the large subunit (LSU) rRNA, and internal transcribed spacer (ITS) genes suggest that the two strains can be assigned to the Trichomonascus/Blastobotrys clade. A maximum likelihood tree based on sequences of the D1/D2 domain revealed that the new species is closely related to the species Trichomonascus ciferrii, Candida allociferrii, and Candida mucifera. The new species could be distinguished from the closely related species by its ability to grow at 42 °C and the inability to assimilate D-arabinose and D-mannitol. The name B. persicus sp. nov. is proposed for the new anamorphic species. The type strain of B. persicus is AHD129-1T = IBRC-M30238T = CBS 14259T, and the Mycobank number is MB 819148.

PAMAM-dendrimer Enhanced Antibacterial Effect of Vancomycin Hydrochloride Against Gram-Negative Bacteria.

PURPOSE: The antibacterial activity of some antibiotics is specific to either Gram-positive or Gram-negative bacteria.  There are different mechanisms behind such insensitivities like inability of antibiotics to permeate through some bacterial membranes, as is the case for vancomycin in Gram-negative bacteria. The present investigation tries to overcome this problem by dendrimers, in order to make Gram-negative bacteria responsive to vancomycin. METHODS: The effects of generations 3 (G3) and 5 (G5) polyamidoamine amine-terminated dendrimers (NH2-PAMAM), on the antibacterial activity of vancomycin, were evaluated. Vancomycin-PAMAM dendrimers complexes were prepared and their antibacterial activities were evaluated by determination of their "minimum inhibitory concentration (MIC)", "minimum bactericidal concentration" and "fractional inhibitory concentration index" values against two Gram-positive and four Gram-negative bacteria, using broth micro-dilution method. The complexation of vancomycin and dendrimers was also assessed by in vitro release studies across dialysis tubing using a developed HPLC method. RESULTS: Results showed that vancomycin solution was effective against Gram-positive bacteria, but, was not effective in Gram-negative ones. Vancomycin-PAMAM dendrimers exhibited significant antibacterial efficacy against Gram-negative bacteria resulting in a decline of vancomycin MIC values by about 2, 2, 4 and 64 times in E. coli, K. pneumonia, S. typhimurium and P. aeruginosa, respectively. Results also showed that enhanced effect by G5 is more than G3. Dendrimers did not affect antibacterial activity of vancomycin in Gram-positive bacteria, as no permeation problem exists here. CONCLUSIONS: The present study revealed that both G3 and G5 cationic PAMAM dendrimers are able to make Gram-negative bacteria sensitive to vancomycin, resulting in decline of MIC values up to 64 times, possibly by increasing its permeation through bacterial membrane. These results look promising for broadening the antibacterial spectrum of vancomycin and such a strategy might be used for increasing the overall life of antibiotics.

Evaluation of heavy petroleum degradation using bacterial-fungal mixed cultures.

The use of potent microbial mixed cultures is a promising method for the bioremediation of recalcitrant compounds. In this study, eight molds, three yeasts, and four bacterial isolates were screened from an aged oil-polluted area. An oil degradation assay with various combinations including Bacterial Mixed Culture (BMC), Fungal Mixed Culture (FMC), Fungal-Bacterial Mixed Culture (TMC), and Sequential Fungal-Bacterial Mixed Culture (SMC) was investigated. The results indicated that the SMC culture had the highest yield of degradation (65.96%) in comparison with the degradation yields of TMC, FMC and BMC, which were 59.04%, 56.64%, and 47.56%, respectively. The degradation of saturates, aromatics, resins, and asphaltenes in the crude oil found using the Iatroscan system were, as follows: 64.21%, and 67.63% for aromatics, 72.90%, and 73.59% for saturates, and 53.88% and 58.25% for resins with respect to the TMC and SMC cultures as the superior mixed cultures. The growth rates of yeasts, molds, and bacteria in the TMC and SMC cultures were compared for further evaluation of the role of each microorganism in the degradation. Our findings support the use of mixed cultures in the bioremediation of recalcitrant petroleum pollution.

Optimization of recombinant ß-NGF expression in Escherichia coli using response surface methodology.

Human nerve growth factor a member of the neurotrophin family can be used to treat neurodegenerative diseases. As it has disulfide bonds in its structure, periplasmic expression of it using appropriate signal sequence is beneficial. Therefore, in this work ß-nerve growth factor (ß-NGF) was expressed in Escherichia coli using pET39b expression vector containing DsbA signal sequence. In an initial step, the effect of isopropyl ß-D-1-thiogalactopyranoside (IPTG) and lactose concentration as inducer on protein production was investigated using response surface methodology. Then the effect of different postinduction time and temperature on protein production was studied. Our results indicated that the highest ß-NGF production was achieved with 1 mM IPTG and low concentrations of lactose (0-2% w/v), low cultivation temperature of 25°C and postinduction time of 2 hr. Also following ß-NGF purification, bioassay test using PC12 cell line was done. The biological activity of the purified ß-NGF showed a similar cell proliferation activity with the standard recombinant human ß-NGF. In conclusion, the results indicated an optimized upstream process to obtain high yields of biologically active ß-NGF.