Influence of Substrates on the Surface Characteristics and Membrane Proteome of Fibrobacter succinogenes S85

Although Fibrobacter succinogenes S85 is one of the most proficient cellulose degrading bacteria among all mesophilic organisms in the rumen of herbivores, the molecular mechanism behind cellulose degradation by this bacterium is not fully elucidated. Previous studies have indicated that cell surface proteins might play a role in adhesion to and subsequent degradation of cellulose in this bacterium. It has also been suggested that cellulose degradation machinery on the surface may be selectively expressed in response to the presence of cellulose. Based on the genome sequence, several models of cellulose degradation have been suggested. The aim of this study is to evaluate the role of the cell envelope proteins in adhesion to cellulose and to gain a better understanding of the subsequent cellulose degradation mechanism in this bacterium. Comparative analysis of the surface (exposed outer membrane) chemistry of the cells grown in glucose, acid-swollen cellulose and microcrystalline cellulose using physico-chemical characterisation techniques such as electrophoretic mobility analysis, microbial adhesion to hydrocarbons assay and Fourier transform infra-red spectroscopy, suggest that adhesion to cellulose is a consequence of an increase in protein display and a concomitant reduction in the cell surface polysaccharides in the presence of cellulose. In order to gain further understanding of the molecular mechanism of cellulose degradation in this bacterium, the cell envelope-associated proteins were enriched using affinity purification and identified by tandem mass spectrometry. In total, 185 cell envelope-associated proteins were confidently identified. Of these, 25 proteins are predicted to be involved in cellulose adhesion and degradation, and 43 proteins are involved in solute transport and energy generation. Our results supports the model that cellulose degradation in F. succinogenes occurs at the outer membrane with active transport of cellodextrins across for further metabolism of cellodextrins to glucose in the periplasmic space and inner cytoplasmic membrane

Potential therapeutic applications of microbial surface-activecompounds

Numerous investigations of microbial surface-active compounds or biosurfactants over the past two decades have led to the discovery of many interesting physicochemical and biological properties including antimicrobial, anti-biofilm and therapeutic among many other pharmaceutical and medical applications. Microbial control and inhibition strategies involving the use of antibiotics are becoming continually challenged due to the emergence of resistant strains mostly embedded within biofilm formations that are difficult to eradicate. Different aspects of antimicrobial and anti-biofilm control are becoming issues of increasing importance in clinical, hygiene, therapeutic and other applications. Biosurfactants research has resulted in increasing interest into their ability to inhibit microbial activity and disperse microbial biofilms in addition to being mostly nontoxic and stable at extremes conditions. Some biosurfactants are now in use in clinical, food and environmental fields, whilst others remain under investigation and development. The dispersal properties of biosurfactants have been shown to rival that of conventional inhibitory agents against bacterial, fungal and yeast biofilms as well as viral membrane structures. This presents them as potential candidates for future uses in new generations of antimicrobial agents or as adjuvants to other antibiotics and use as preservatives for microbial suppression and eradication strategies

Antibiotic resistance in isolated bacteria from urban sewage and copper smeltery industrial wastewater

Background and Objective: Pollution due to the heavy metals is a problem that may have negative consequences on the hydrosphere. Identification of microorganisms resistant to heavy metals plays an important role in relation to environmental pollution bioremediation. This study was done to assess the antibiotic resistance in isolated bacteria from urban sewage and copper smeltery industrial wastewater. Materials and Methods: This laboratory study was done on the wastewater samples from urban sewage and copper smeltery in Isfahan-Iran, during 2011-12. Heavy metal resistant microorganisms were isolated and enumerated after serial dilution and culturing on PHG agar plates supplemented with 0.5 mM of each heavy metal. The pattern of resistance was assigned by Minimum Inhibitory Concentration (MIC). Antibiotic resistance toward following medicines Ofloxacine, Penicilline, Sulfometoxasole, Lincomycin, Kanamycin, Streptomycin, Clindamycin, Vancomycin, Cefradin and Neomycin were subsequently investigated. Results: The greatest resistance in isolated bacteria has been related to the Ni (MIC: 24 mM) that’s related to the genus of Klebsiella and its minimum MIC is 2mM that’s of Acinetobacter lwoffi, Providencia stuartii, Branhamella. The minimum degree of resistance is related to Cu. Its Maximum MIC related to this metal in swage is 2 mM that’s of Klebsiella pneumoniae and its minimum degree of resistance in copper smeltery effluent is arranged as 1mM related to genus of Pseudomonas alkaligenes. In examining multi metal resistance pattern, the greatest resistance with 8 mM MIC has been related to the Cd, that’s of Ni resistant Moraxella osloensis in Copper smeltery effluent. The highest portion of isolated bacteria were resistant to Pb (P<0.05). The highest resistance of refirary wastewater was to Ni (MIC: 2 mM), which belong to Klebsiella (P<0.05). The lowest belong to Acine to bacter Lwoffi providencia Stuartii, Branhamella (MIC: 2mM) (P<0.05). In urban sewage: the highest resistance belong to copper, which was seen in Klebsiella Pneumoniae (MIC: 2mM). In Antibiogram tests of Klebsiella, Moraxella and Escherichia, it was demonstrated that the metal resistant bacteria were also resistant toward Lincomycin, Kanamycin, Streptomycin, Clindamycin, Vancomycin, Cefradin and Neomycin, as well. Conclusion: Increasing heavy metal resistance in the environment leads to increased antibiotic resistance toward microorganisms

Polycarbonate biodegradation by isolated molds using clear-zone and atomic force microscopic methods

The accumulation of dry waste containing synthetic polymers due to their resistance to microorganisms and other environmental factors has posed some serious problems to the environment in recent years. On the other hand, plastics constitute the foundations of economy as they are widely used in agriculture, constructions, packaging, health care and also medicine. The aim of this research was to investigate the role of different isolated fungi in the degradation of polycarbonate polymers. For this purpose, sampling was done using the garden soil and waste leachate from Isfahan Waste Management Organization. Samples were enriched in the liquid mineral salt medium supplemented with polycarbonate and then were transferred to the same medium solidified with agar to isolate and identify different fungi. Finally, their biodegradation activity was investigated with the help of clear- zone and atomic force microscopic (AFM) techniques, and also lipase and amylase production was tested. Among 15 isolated genera of mold fungi, Fusarium , Ulocladium , Chrysosporium and Penicillium showed biodegradation activity. According to the diameter of clear zone around the fungal colonies and also AFM results, the highest rate of degradation was related to Fusarium. Lipase activity of all isolated fungi was positive, but amylase activity of Ulocladium was negative. It can be concluded that some fungal strains such as Fusarium can be used for the biodegrada- tion of plastic materials as it leads to a very eco-friendly biodegradation process