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Bacterial cellulose (BC) is a very fascinating microbial biopolymer which is mainly produced by Gluconacetobacter xylinum. Optimization of BC production by G. xylinum was performed based on scale-down studies in miniature-bioreactor and response surface methodology in which the optimum pH value (6.5) and shaking rate (50 rpm) were obtained. The static culture condition for BC production has newly been defined. Nanostructure of BC includes nanofibers up to (60 nm) and nanoporosity up to (265 nm) was observed by scanning electron microscopy. By Fourier transform infrared spectroscopy study, the most expected BC interaction is nucleophilic interaction. MTT assay showed high biocompatibility. Appropriate mechanical strength (0.37 MPa) and Young’s modulus (3.36 MPa) evinced BC scaffold utilization for skin tissue. The results indicate that BC sheets can be utilized in biomedical application and nanotechnology approaches.

A longstanding awareness in generating resistance to common antimicrobial therapies by gram-negative bacteria has made them a major threat to global health. The application of antimicrobial peptides as a therapeutic agent would be a great opportunity to combat bacterial diseases. Here, we introduce a new antimicrobial peptide (∼8.5 kDa) from probiotic strain Lactobacillus acidophilus ATCC 4356, designated as Acidocin 4356 (ACD). This multifunctional peptide exerts its anti-infective ability against Pseudomonas aeruginosa through an inhibitory action on virulence factors, bacterial killing, and biofilm degradation. Reliable performance over tough physiological conditions and low hemolytic activity confirmed a new hope for the therapeutic setting. Antibacterial kinetic studies using flow cytometry technique showed that the ACD activity is related to the change in permeability of the membrane. The results obtained from molecular dynamic (MD) simulation were perfectly suited to the experimental data of ACD behavior. The structure-function relationship of this natural compound, along with the results of TEM analysis and molecular dynamic (MD) simulation, confirmed the ability of the ACD aimed at enhancing bacterial membrane perturbation. The peptide was effective in the treatment of P. aeruginosa infection in mouse model. The results support the therapeutic potential of ACD for the treatment of Pseudomonas infections. Importance Multidrug-resistant bacteria are a major threat to global health, and Pseudomonas bacterium with the ability to form biofilms has considered as one of the main causative agents of nosocomial infections. Traditional antibiotics have failed because of increased resistance. So, finding new biocompatible antibacterial drugs are essential. Antimicrobial peptides are produced by various organisms as a natural defense mechanism against pathogens, inspiring for the possible design of the next generation of antibiotics. In this study, a new antimicrobial peptide was isolated from Lactobacillus acidophilus ATCC 4356, counteracting both biofilm and planktonic cells of P. aeruginosa. A detailed investigation was then conducted concerning the functional mechanism of this peptide by using fluorescence techniques, electron microscopy, and in silico methods. The antibacterial and antibiofilm properties of this peptide may be important in the treatment of Pseudomonas infections.

The catheterized urinary tract provides ideal conditions for the development of biofilm populations. Catheter-associated urinary tract infections (CAUTIs) are recalcitrant to existing antimicrobial treatments; therefore, established biofilms are not eradicated completely after treatment and surviving biofilm cells will carry on the infection. Cis-2-decenoic acid (CDA), an unsaturated fatty acid, is capable of inhibiting biofilm formation by Pseudomonas aeruginosa and of inducing the dispersion of established biofilms by multiple types of micro-organisms. Here, the ability of CDA to induce dispersal in pre-established single- and dual-species biofilms formed by Escherichia coli and Klebsiella pneumoniae was measured by using both semi-batch and continuous cultures bioassays. Removal of the biofilms by combined CDA and antibiotics (ciprofloxacin or ampicillin) was evaluated using microtitre plate assays (crystal violet staining). The c.f.u. counts were determined to assess the potential of combined CDA treatments to kill and eradicate pre-established biofilms formed on catheters. The effects of combined CDA treatments on biofilm surface area and bacteria viability were evaluated using fluorescence microscopy, digital image analysis and live/dead staining. To investigate the ability of CDA to prevent biofilm formation, single and mixed cultures were grown in the presenceand absence of CDA. Treatment of pre-established biofilms with only 310 nM CDA resulted in at least threefold increase in the number of planktonic cells in all cultures tested. Whilst none of the antibiotics alone exerted a significant effect on c.f.u. counts and percentage of surface area covered by the biofilms, combined CDA treatments led to at least a 78 % reduction in biofilm biomass in all cases. Moreover, most of the biofilm cells remaining on the surface were killed by antibiotics. The addition of 310 nM CDA significantly prevented biofilm formation by the tested micro-organisms, even within mixed cultures, indicating the ability of CDA to inhibit biofilm formation by other types of bacteria in addition to Pseudomonas aeruginosa. These findings suggested that the biofilm-preventive characteristics of CDA make it a noble candidate for inhibition of biofilm-associated infections such as CAUTIs, which paves the way toward developing new strategies to control biofilms in clinical as well as industrial settings.

Denitrification is the biological reduction of nitrate to nitrite and then nitrogen oxides and/or dinitrogen. The process carry out by different taxa of bacteria called "denitrifiers" that use nitrate or nitrite as final electron acceptor in their respiration. To estimate the number of denitrifiers, there are many ways such as molecular methods, measuring enzyme concentration, determining MPN of bacteria etc. Although MPN method is time consuming and approximatively but it is used as a common method to determination the denitrifier population because this method does not require special facilities and seems to be easier than other methods.

Ammonification is part of nitrogen cycle which organic nitrogen sources biodegradation into NH4+. This process carried out by "ammonifiers". For enumeration ammonifiers can use MPN method. In this study, to estimate the MPN of denitrifiers a Excel-based software was used.

This study assessed the role of a new Acinetobacter calcoaceticus strain, GSN3, with biofilm-forming and phenol-degrading abilities. Three biofilm reactors were spiked with activated sludge (R1), green fluorescent plasmid (GFP) tagged GSN3 (R2), and their combination (R3). More than 99% phenol removal was achieved during four weeks in R3 while this efficiency was reached after two and four further operational weeks in R2 and R1, respectively. Confocal scanning electron microscopy revealed that GSN3-gfp strains appeared mostly in the deeper layers of the biofilm in R3. After four weeks, almost 7.07 × 107 more attached sludge cells were counted per carrier in R3 in comparison to R1. Additionally, the higher numbers of GSN3-gfp in R2 were unable to increase the efficiency as much as measured in R3. The presence of GSN3-gfp in R3 conveyed advantages, including enhancement of cell immobilization, population diversity, metabolic cooperation and ultimately treatment efficiency.

In the last decades, mushroom polysaccharides as important complex biopolymer; have attracted considerable attention by their preference such as bioactivity, low toxicity and environmental friendly. Nowadays, most of the antioxidants used are synthetic and have been suspected of being responsible for liver damage and carcinogenesis. Therefore, extracellular polysaccharides may be one of the most promising groups of antioxidant compounds. High demand for mushroom polysaccharide, coupled with a long fermentation period and low production, the submerged cultivation of fungal mycelia is a favorable and efficient process for polysaccharide production. Therefore, the development of novel and highly efficient strategies for mushroom polysaccharide production continues to be a subject of research interest. Herein, the strain SF1344 was isolated from forest area of Golestan province, North of Iran and antioxidant activity of the biopolymer was evaluated. Moreover, the structural characterization of the biopolymer was studied.

Aims: The aim of this study was to isolate a novel yeast strain, evaluate biosurfactant production by the strain and characterize the major product. Methods and Results: The strain SAM20, isolated from grass, identified as Sporisorium sp. aff. sorghi based on phylogenetic analyses. The strain produced approximately 32gl−1 glycolipid biosurfactants from 40gl−1 soybean oil after 7days at 28°C. The glycolipids showed a unique pattern of mannosylerythritol lipids (MELs) on thin layer chromatography plate compared to those hitherto reported. Structural characterization of the major product, called GL-A, revealed that it was mainly tri-acetylated mono-acylated MELs (MEL-A2) with C14:0, C16:0, C12:0 or C14:1 as the hydrophobic chain. The critical micelle concentration (CMC), the surface tension at CMC and hydrophilic–lipophilic balance value for GL-A were estimated to be 20mgl−1, 30·0mNm−1 and 8·7, respectively. Conclusions: A MEL-A2 with novel composition and surface activities was efficiently produced from a novel MEL producer. This is the first report on production of MEL-A2 as the major product and from soybean oil. The biosurfactant has potential application as a wetting agent and oil-in-water emulsifier. Significance and Impact of the Study: Discovery of novel structures and novel strains is valuable for further commercial development and application of MELs. Sporisorium sp. aff. sorghi SAM20 can be considered as a potential candidate for commercial production of biosurfactants.

During a study on the biodiversity of yeasts and yeast-like ascomycetes from wild plants in Iran, four strains of yeast-like filamentous fungi were isolated from a healthy plant of Euphorbia polycaulis in the Qom Province, Iran (IR. of). All four strains formed small hyaline one-celled conidia from integrated conidiogenous cells directly on hyphae and sometimes on discrete phialides, as well as by microcyclic conidiation. Two strains additionally produced conidia in conidiomata that open by rupture. The internal transcribed spacer (ITS) sequences suggested the placement of these strains in the genera Collophorina (Leotiomycetes) and Coniochaeta (Sordariomycetes), respectively. Blast search results on NCBI GenBank and phylogenetic analyses of ITS, the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and the translation elongation factor 1α (EF-1α) sequences, and the nuclear large subunit ribosomal gene (LSU), partial actin (ACT), and β-tubulin (TUB) sequences, respectively, revealed the isolates to belong to three new species, that are described here as Collophorina euphorbiae, Coniochaeta iranica, and C. euphorbiae. All three species are characterised by morphological, physiological, and molecular data.

Five closely related yeast strains were isolated from soil in Kharg Island, Persian Gulf, Iran, and from fallen fruits in Galle, Sri Lanka, during separate projects. Morphologically, the strains produced white-coloured yeast colonies, with cells that were ovoid to ellipsoidal, making branched, true hyphae and pseudohyphae. Ascospore formation was not observed. Biochemically, the strains were able to fermentD-glucose and weakly fermentD-galactose. The strains could use a wide variety of carbon sources except methanol and hexadecane. Phylogenetic analyses using combined sequences of the small ribosomal subunit and the D1/D2 domains of the LSU, as well as the internal transcribed spacer regions, suggested that these strains belong to the Wickerhamomyces clade and that together they form one strongly supported phylogenetic clade. Differences in their sequences, biochemistry and morphology suggest they are representatives of distinct species of the genus Wickerhamomyces. Therefore, the name Wickerhamomyces orientalis f.a., sp. nov. is proposed to accommodate these novel strains; the type strain is IBRC-M 30103T (=CBS 13306T). The MycoBank number is MB 807323.

Background and Objectives: The US Environmental Protection Agency has suggested faecal enterococci as the primary bacterial indicators. Of more importance is their direct correlation with swimmer-associated gastroenteritis in recreation water quality monitoring. In contrast to other seawater bodies with 3.5% salinity, the recreational waters in the southern coast of the Caspian Sea possess its own salinity (about 1% w/v) and thus require further investigations to determine the capacity of Enterococcus faecalis as the sole primary microbial index in this unique aquatic environment. Materials and Methods: The survey of the presence and survival of E. faecalis as a microbial index in the recreational waters of the southern Caspian Sea was carried out using a microcosm as an experimental model. The concentration of E. faecalis cells in samples of seawater were estimated by a standard membrane filtration method using m-Enterococcus agar as the selective culture medium. As the current standard culture-based methods are not reliable enough for the detection of non-growing, damaged and under-tension bacteria, PCR was used to identify the possible VBNC form of the bacterium after disappearance of the culturable cells. Results and Conclusion: A continuous decline in the number of culturable E. faecalis cells resulted in apparent elimination of the bacteria from seawater in a defined period. Detection of intact DNA was possible in the following 60 days. The salinity of about 1% and the self-purification properties of the Caspian Sea make the conditions feasible for the use of this microorganism as a measure of water quality throughout the region. The results confirmed the presence of damaged bacterial cells, namely VBNC forms, indicating the necessity of examining of the sea water samples by using molecular approaches or repair procedures.

Four strains of a novel ascomycetous yeast species were isolated from flowers in Iran and China. Phylogenetic analysis of the sequences of the ITS region (including 5.8S rRNA gene) and the LSU rRNA gene D1/D2 domains indicated that these strains belong to the Starmerella clade and show divergence from previously described species in this clade. Growth reactions on carbon and nitrogen sources were similar to those observed in related species of the Starmerella clade. Sexual reproduction was not observed after mating tests on different sporulation media. Based on physiological characteristics and phylogeny of rRNA gene sequences, the novel species is most closely related to Candida (iter. nom. Starmerella) powellii and Candida (iter. nom. Starmerella) floricola. It is therefore assigned to the genus Starmerella and described as Starmerella orientalis f.a., sp. nov. The type strain is SAM09T (=IBRC-M 30204T=CBS 14142T). The MycoBank accession number is MB 814379.

Catechol 1, 2-dioxygenase (1, 2-CTD) plays an important role in the biodegradation of most aromatic pollutants (e.g. phenol) by cleaving the bond between the phenolic hydroxyl groups. In this study, we analysed microbial populations in petroleum-contaminated soil samples by the culture-dependent approach and chose one population as a sample location for metagenomic studies. This population showed the largest number of phenol-degrading isolates and the most phylogenetic diversity based on repetitive sequence-based PCR and 16S rDNA analyses. The isolates were assigned mainly to the bacterial genera Acinetobacter and Pseudomonas. To enable maximum recovery of 1, 2-CTD coding sequence from the genomic pool of bacterial populations, we extracted the substrate-induced RNA, reverse-transcribed it to the specific cDNA using primers designed for this purpose and constructed a metagenomic library. Alignment analysis of one recombinant sequence indicated a significant divergence, with the 1, 2-CTD gene of Pseudomonas aeruginosa DK2 as the closest species according to sequence similarity. This result indicates that such specifically designed primers are likely suitable candidates as biomarkers to construct 1, 2-CTD gene-targeted metagenomic libraries. By sequencing the larger clones of this metagenomic library, we hope to obtain novel and unpredicted 1, 2-CTD genes that can contribute to our knowledge of microbial diversity of these genes.

Low grade grape juice concentrate was used as carbon source for xanthan production. Significant factors affecting xanthan concentration, productivity and viscosity were investigated using Plackett-Burman Design. Based on the obtained results, carbon and nitrogen concentrations, inoculum size and agitation rate, were assumed as significant factors. Broth culture viscosity and xanthan concentration were optimized using Response Surface Methodology with four independent variables: carbon source (30, 40, 50 g l-1), ammonium sulfate as nitrogen source (0.5, 1.25, 2 g l-1), agitation (150, 200, 250 rpm) and inoculum size (5, 10, 15% v v-1). Optimum level for each factor was obtained by desirability function approach. The average of xanthan gum production and its viscosity under optimized conditions were recorded as 14.35 g l-1 and 1268 cP, respectively. The average yield of production and productivity of xanthan within 72 h under optimized conditions were 35% and 0.19 g l-1 h-1, respectively. The current study showed the potential of low-grade grape juice concentrate as an economic carbon source for xanthan gum production.