Physical and chromatographic characterization of the surfactin biosurfactant produced by Bacillus subtilis isolate BS5 has been conducted to study its potentiality for industrial application. The crude extract of test surfactin appeared as off-white to buff flake-like amorphous residue with bad odor similar to sour pomegranate. Test surfactin showed solubility in aqueous solution at pH>5 with optimum solubility at pH 8-8.5. It was also soluble in organic solvents like ethanol, acetone, methanol, butanol, chloroform, and dichloromethane. Surfactin crystals appeared rectangular with blunt corners and were arranged perpendicular to each other making a plus sign. Extracted surfactin showed high surface activity, as it could lower the surface tension of water from about 70 to 36 mN/m at approximately 15.6 mg/l. Moreover, test surfactin exhibited excellent stabilities at high temperatures (100 degrees C for up to 1 h at and autoclaving at 121 degrees C for 10 min), salinities (up to 6% NaCl), and over a wide range of pH (5-13). Test surfactin in the cell-free supernatant or crude culture broth forms showed high emulsification indices against kerosene (62.5% and 59%, respectively), diesel (62.5% and 66%, respectively), and motor oil (62% and 66%, respectively). These characters can effectively make test surfactin, in its crude forms, a potential candidate for the use in bioremediation of hydrocarbon-contaminated sites or in the petroleum industry. Chromatographic characterization of test surfactin, using high-performance liquid chromatography technique, revealed that the extracted surfactin contained numerous isoforms, of which six were found in the standard surfactin preparation (Fluka). Additional peaks appeared in the test surfactin and not in the standard one. These peaks may correspond to new surfactin isoforms that may be present in the test surfactin produced by B. subtilis isolate BS5.

Bacillus subtilis BS5 is a soil isolate that produces promising yield of surfactin biosurfactant in mineral salts medium (MSM). It was found that cellular growth and surfactin production in MSM were greatly affected by the environmental fermentation conditions and the medium components (carbon and nitrogen sources and minerals). Optimum environmental conditions for high surfactin production on the shake flask level were found to be a slightly acidic initial pH (6.5-6.8), an incubation temperature of 30 degrees C, a 90% volumetric aeration percentage, and an inoculum size of 2% v/v. For media components, it was found that the optimum carbon source was molasses (160 ml/l), whereas the optimum nitrogen source was NaNO(3) (5 g/l) and the optimum trace elements were ZnSO(4).7H(2)O (0.16 g/l), FeCl(3).6H(2)O (0.27 g/l), and MnSO(4).H(2)O (0.017 g/l). A modified MSM (molasses MSM), combining the optimum medium components, was formulated and resulted in threefold increase in surfactin productivity that reached 1.12 g/l. No plasmid could be detected in the tested isolate, revealing that biosurfactant production by B. subtilis isolate BS5 is chromosomally mediated but not plasmid-mediated.

Rhamnolipid produced by Pseudomonas aeruginosa isolate Bs20 is viscous sticky oily yellowish brown liquid with a fruity odor. It showed solubility at aqueous pH > 4 with optimum solubility at pH 7-7.5 and freely soluble in ethyl acetate. This biosurfactant has a very high surface activity as it could lower the surface tension of water to 30 mN/m at about 13.4 mg/L, and it exhibited excellent stabilities at high temperatures (heating at 100 degrees C for 1 h and autoclaving at 121 degrees C for 10 min), salinities (up to 6% NaCl), and pH values (up to pH 13). The produced biosurfactant can be used in the crude form either as cell-free or cell-containing culture broth of the grown bacteria, since both preparations showed high emulsification indices ranged between 59% and 66% against kerosene, diesel, and motor oil. These characters make the test rhamnolipid a potential candidate for use in bioremediation of hydrocarbon-contaminated sites or in the petroleum industry. High-performance thin-layer chromatography densitometry revealed that the extracted rhamnolipid contained the two most active rhamnolipid homologues dirhamno dilipidic rhamnolipid and monorhamno dilipidic rhamnolipid at 44% and 56%, respectively, as compared to 51% and 29.5%, respectively, in a standard rhamnolipid preparation. The nature and ratio of these two rhamnolipid homologues showed to be strain dependent rather than medium-component dependent.

Background. Enteric fever is a global health problem, and rapidly developing resistance to various drugs makes the situation more alarming. The potential use of Lactobacillus to control typhoid fever represents a promising approach, as it may exert protective actions through various mechanisms. Methods. In this study, the probiotic potential and antagonistic activities of 32 Lactobacillus isolates against Salmonella typhi were evaluated. The antimicrobial activity of cell free supernatants of Lactobacillus isolates, interference of Lactobacillus isolates with the Salmonella adherence and invasion, cytoprotective effect of Lactobacillus isolates, and possibility of concurrent use of tested Lactobacillus isolates and antibiotics were evaluated by testing their susceptibilities to antimicrobial agents, and their oxygen tolerance was also examined. Results. The results revealed that twelve Lactobacillus isolates could protect against Salmonella typhi infection through interference with both its growth and its virulence properties, such as adherence, invasion, and cytotoxicity. These Lactobacillus isolates exhibited MIC values for ciprofloxacin higher than those of Salmonella typhi and oxygen tolerance and were identified as Lactobacillus plantarum. Conclusion. The tested Lactobacillus plantarum isolates can be introduced as potential novel candidates that have to be subjected for in vivo and application studies for treatment and control of typhoid fever.

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In this article, some mucolytic agents were tested for their activity to prevent bacterial adherence to mammalian cells. Preliminary screening for antiadherent activity showed that ambroxol, bromhexine, ammonium chloride, and ammonium acetate but neither guaiphenesin nor carbocysteine significantly reduced the adherence of the tested clinical isolates to cultured mammalian cells. The antiadherent effect of such agents was observed when mammalian cells were treated with these agents either before or after bacterial adherence, and this effect was exhibited in a dose-dependent manner. The minimum concentrations of ambroxol, bromhexine, ammonium chloride, and ammonium acetate required for mammalian cells treatment to prevent bacterial adherence were 2.5, 5, 50, and 20 ng/ml, respectively, whereas significantly higher mucolytic concentrations were required to eradicate bacteria that adhered to mammalian cells. Upon treatment of mammalian cells with mucolytics, the maximum reduction in adherence of the tested isolates attained by ambroxol, bromhexine, ammonium chloride, ammonium acetate were 99%, 98%, 75%, and 54% to that of control, respectively. Insignificant difference existed between the antiadherent activities of ambroxol and bromhexine, while both agents had significantly higher effect than ammonium chloride and ammonium acetate. Pretreatment of the immobilized mucin with ambroxol, bromhexine, ammonium chloride, or ammonium acetate reduced the adherence of Pseudomonas aeruginosa, Escherichia coli, and staphylococcal isolates to this receptor analogue. A strong correlation was observed for the antiadherent activity of the tested mucolytics in case of mammalian cells and immobilized mucin. Moreover, pretreatment of the immobilized receptor analogues chondroitin sulfate-B and heparin with the abovementioned agents significantly reduced the adherence of Staphylococcus aureus, P. aeruginosa, and E. coli isolates to such immobilized glycoproteins.

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Polyoma, Newcastle disease virus, and adenovirus, as well as two coliphages, lambda and T4, were inactivated by strong base quaternary ammonium anionexchange resin-triiodide. Organic matter interfered with viral inactivation capability of the resin-triiodide. The viruses, as they were being inactivated by the resin disinfectant beads, were not retained or filtered by the beads. A strongly basic quaternary ammonium anionexchange resin-triiodide (resin-I3) complex developed in our laboratories proved to be an effective demand-type disinfectant against a wide variety of bacteria (24). The viricidal capability remains in question. Preliminary reports released in 1975 and 1979 (14, 15) tell of viricidal activity, and two papers published in 1980 (16, 21) describe chemical properties of the disinfectant.