Adhesion of an Amylolytic Arthrobacter sp. to Starch-Containing Plastic Films

Adhesion of Lactobacillus amylovorus to Insoluble and Derivatized Cornstarch Granules

Approximately 70% of the cells in a suspension of the amylolytic bacterium Lactobacillus amylovorus bind to cornstarch granules within 30 min at 25 degrees C. More than 60% of the bound bacteria were removed by formaldehyde (2%) or glycine (1 M) at pH 2.0. More than 90% of the bound bacteria were removed by MgCl(2) (2 M; pH 7.0). Binding of L. amylovorus to cornstarch was inhibited in heat-killed cells and in cells that had been pretreated with glutaraldehyde, formaldehyde, sodium azide, trypsin, or 1% soluble potato starch. Bacterial binding to cornstarch appeared to correlate with both the concentration of cornstarch in the suspension and the amylose content in the granules. The ability of L. amylovorus to adhere to cornstarch granules was reduced for granules that had been extracted with HCl-ethanol, HCl-methanol, HCl-propanol, or HCl-butanol. Chemical derivatization of cornstarch resulted in a wide variety of adhesion responses by these bacteria. For example, 2-O-butyl starch (degree of substitution, 0.09) enhanced adhesion, whereas two palmitate starches (degree of substitution, 0.48 and 0.09) exhibited reduced adhesion activities. 2-O-(2-hydroxybutyl) starch and starch-poly(ethylene-co-acrylic acid) ester showed adhesion activities similar to those of the nonderivatized starch controls.

Adhesive properties of a symbiotic bacterium from a wood-boring marine shipworm

Adhesive properties of a cellulolytic, nitrogen-fixing bacterium isolated from a marine shipworm by Waterbury et al. (J. B. Waterbury, C. B. Calloway, and R. D. Turner, Science 221:1401-1403, 1983) are described. S-labeled cells of the shipworm bacterium bound preferentially to Whatman no. 1 cellulose filter paper, compared with its binding to other cellulose substrata or substrata lacking cellulose. The ability of the bacteria to bind to Whatman no. 1 filter paper was significantly reduced by glutaraldehyde or heat treatment of cells. Pretreatment of cells with azide, valinomycin, gramicidin-D, bis-hexafluoroacetylacetone (1799), or carbonyl cyanide-p-trifluoromethoxyphenylhydrazone inhibited adhesion activity. Cells pretreated with pronase or trypsin also exhibited reduced binding activity, but chymotrypsin and peptidase had no effect on adhesion activity. Cellodextrins and methyl cellulose 15 inhibited the adhesion of shipworm bacteria to filter paper, whereas glucose, cellobiose, and soluble carboxymethyl cellulose had no significant effect. The divalent cation chelators EDTA and EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N'N'-tetraacetic acid] had little or no effect on adhesive properties of shipworm bacteria. Also, preabsorbing the substratum with extracellular endoglucanase isolated from the shipworm bacterium or 1% bovine serum albumin had no apparent effect on bacterial binding. Low concentrations (0.01%) of sodium dodecyl sulfate solubilized a fraction from whole cells, which appeared to be involved in cellular binding activity. After removal of sodium dodecyl sulfate, several proteins in this fraction associated with intact cells. These cells exhibited up to 50% enhanced binding to filter paper in comparison to cells which had not been exposed to the sodium dodecyl sulfate-solubilized fraction.

The effect of intestinal bacteria adherence on drug diffusion through solid films under stationary conditions

PURPOSE

To study the in vitro and in vivo the role of surface bacterial adhesion on the diffusion of model drugs at stationary conditions.

METHODS

Salicylic acid (SA) diffusion through ethyl cellulose (EC) films was measured in vitro in side-by-side diffusion cells with and without E. coli of intestinal origin. Insulin (I) release from paper strips coated or uncoated with pectin films, with or without antibiotic treatment, was measured in vivo in conscious rats after cecal implantation by comparing blood glucose levels at Tmax of the pharmacodynamic effect.

RESULTS

During five hours of diffusion studies which were performed immediately following incubation of EC films with bacteria, the diffusion rate of SA throughout the films was 2.72-fold lower in the presence of bacteria compared with the diffusion rate in the control studies conducted without bacteria. The mean blood glucose levels dropped in the rat to 40.6 +/- 21.6% of glucose basal levels within 2.4 +/- 1.4 h when uncoated I solid carriers were used. Glucose levels did not change for pectin-coated dosage forms. After antibiotic treatment which prevented the formation of bacterial biofilm on the surface of the I solid dosage forms, blood glucose levels dropped to 22.0 +/- 4.7% and 50.9 +/- 20.5% of glucose basal levels within 7.4 +/- 2.6 h and 1.8 +/- 0.9 h for pectin uncoated or coated dosage forms, respectively. Maximum bacterial adherence occurred at stationary conditions (RPM = 0), while at maximum agitation (200 RPM), almost no adherence occurred.

CONCLUSIONS

(a) Bacterial adherence shows down the diffusion rate of SA through EC films; (b) Under stationary conditions bacterial adherence may also interfere with drug release from biodegradable (pectin) films; (c) Successful functioning of biodegradable colon-specific delivery systems depends on agitation and surface friction in the lumen of the colon.

Isotactic polypropylene biodegradation by a microbial community: physicochemical characterization of metabolites produced

From a selective enrichment culture prepared with different soil samples on starch-containing polyethylene we isolated four microaerophilic microbial communities able to grow on this kind of plastic with no additional carbon source. One consortium, designated community 3S, was tested with pure isotactic polypropylene to determine whether the consortium was able to degrade this polymer. Polypropylene strips were incubated for 5 months in a mineral medium containing sodium lactate and glucose in screw-cap bottles. Dichloromethane crude extracts of the cultures revealed that the weight of extracted materials increased with incubation time, while the polypropylene sample weight decreased. The extracted materials were characterized by performing chromatographic and spectral analyses (thin-layer chromatography, liquid chromatography, gas chromatography-mass spectrometry, infrared spectrometry, nuclear magnetic resonance). Three main fractions were detected and analyzed; a mixture of hydrocarbons at different degrees of functionalization was found together with a mixture of aromatic esters, as the plasticizers usually added to polyolefinic structures.

Binding of Extracellular Carboxymethylcellulase Activity from the Marine Shipworm Bacterium to Insoluble Cellulosic Substrates

The binding of extracellular endoglucanase, a carboxymethylcellulase (CMCase), produced by the marine shipworm bacterium to insoluble cellulose substrates was investigated. Up to 70% of CMCase activity bound to cellulosic substrates, and less than 10% bound to noncellulosic substrates. CMCase binding to cellulose was enhanced in basal salt medium or sodium phosphate buffer containing 0.5 M NaCl. Increased cellulose particle size correlated with decreased CMCase binding. Also, cellulose treated with either 5 N NaOH or commercial cellulase reduced the CMCase binding to these surfaces. Pretreatment of CMCase preparations with 0.01% sodium dodecyl sulfate, 5% β-mercaptoethanol, and 5 mM EDTA or ethylene glycol-bis(β-aminoethyl ether)- N,N,N′,N′ -tetraacetic acid (EGTA) had little effect on binding to cellulose. While pretreatment of CMCase with trypsin, chymotrypsin, and pronase had little effect on CMCase enzymatic activity, the ability to bind to cellulose was greatly diminished by these treatments.

Biodegradation of Degradable Plastic Polyethylene by Phanerochaete and Streptomyces Species

The ability of lignin-degrading microorganisms to attack degradable plastics was investigated in pure shake flask culture studies. The degradable plastic used in this study was produced commercially by using the Archer-Daniels-Midland POLYCLEAN masterbatch and contained pro-oxidant and 6% starch. The known lignin-degrading bacteria Streptomyces viridosporus T7A, S. badius 252, and S. setonii 75Vi2 and fungus Phanerochaete chrysosporium were used. Pro-oxidant activity was accelerated by placing a sheet of plastic into a drying oven at 70°C under atmospheric pressure and air for 0, 4, 8, 12, 16, or 20 days. The effect of 2-, 4-, and 8-week longwave UV irradiation at 365 nm on plastic biodegradability was also investigated. For shake flask cultures, plastics were chemically disinfected and incubated-shaken at 125 rpm at 37°C in 0.6% yeast extract medium (pH 7.1) for Streptomyces spp. and at 30°C for the fungus in 3% malt extract medium (pH 4.5) for 4 weeks along with an uninoculated control for each treatment. Weight loss data were inconclusive because of cell mass accumulation. For almost every 70°C heat-treated film, the Streptomyces spp. demonstrated a further reduction in percent elongation and polyethylene molecular weight average when compared with the corresponding uninoculated control. Significant ( P < 0.05) reductions were demonstrated for the 4- and 8-day heat-treated films by all three bacteria. Heat-treated films incubated with P. chrysosporium consistently demonstrated higher percent elongation and molecular weight average than the corresponding uninoculated controls, but were lower than the corresponding zero controls (heat-treated films without 4-week incubation). The 2- and 4-week UV-treated films showed the greatest biodegradation by all three bacteria. Virtually no degradation by the fungus was observed. To our knowledge, this is the first report demonstrating bacterial degradation of these oxidized polyethylenes in pure culture.

High-Molecular-Weight Amylase Activities from Bacteria Degrading Starch-Plastic Films

Amylases having unusually high molecular weights ( M r , >150,000) were found in culture supernatants of an environmentally derived microbial mixed culture selected for its ability to utilize starch-containing plastic films as sole carbon sources. The mixed culture produced amylases active at pHs 5.5 and 8.0.