Fred Stutzenberger

Nanotechnology in the detection and control of microorganisms.

Publisher Summary “Nano-” denotes nanometer (10 –9 meter). Nanomaterials can be produced from various bulk materials, with either organic or inorganic components as their major constituents. The nanomaterials to be discussed in this chapter are divided into three categories: polymeric, semiconductor, and metallic. Organic polymeric nanomaterials include a large and diverse group of carbon nanotubes, emulsions, liposomes, dendrimers, and other organic polymers. Although nanotechnology is still new, nanomaterials have been widely used in electronics, magnetics and optoelectronics, energy and catalytic, biomedicine, pharmaceuticals, clothing, cosmetics, and environmental detection and monitoring. The chapter discusses the current status of three major types of nanomaterials as they are applied in the control and detection of various microorganisms: polymeric nanomaterials (nanoparticles, nanotubes, nanoemulsion) that are conjugated with different biofunctionalities, fluorescent agents and the applications of semiconductor nanocrystals as fluorescent tag/label/probe for the rapid and sensitive identification and detection of pathogens in pure or mixed microbial cultures, and metallic nanomaterials such as Ag, TiO 2 , and MgO that are used in antimicrobial applications.

Vector potential of houseflies for the bacterium Aeromonas caviae

Abstract Houseflies, Musca domestica Linnaeus (Diptera: Muscidae), have been implicated as vectors or transporters of numerous gastrointestinal pathogens encountered during feeding and ovipositing on faeces. The putative enteropathogen Aeromonas caviae (Proteobacteria: Aeromonadaceae) may be present in faeces of humans and livestock. Recently A. caviae was detected in houseflies by PCR and isolated by culture methods. In this study, we assessed the vector potential of houseflies for A. caviae relative to multiplication and persistence of the bacterium in the fly and to contamination of other flies and food materials. In experimentally fed houseflies, the number of bacteria increased up to 2 days post‐ingestion (d PI) and then decreased significantly 3 d PI. A large number of bacteria was detected in the vomitus and faeces of infected flies at 2–3 d PI. The bacteria persisted in flies for up to 8 d PI, but numbers were low. Experimentally infected flies transmitted A. caviae to chicken meat, and transmissibility was directly correlated with exposure time. Flies contaminated the meat for up to 7 d PI; however, a significant decrease in contamination was observed 2–3 d PI. In the fly‐to‐fly transmission experiments, the transmission of A. caviae was observed and was apparently mediated by flies sharing food. These results support houseflies as potential vectors for A. caviae because the bacterium multiplied, persisted in flies for up to 8 d PI, and could be transmitted to human food items.

Detection of Aeromonas caviae in the common housefly Musca domestica by culture and polymerase chain reaction.

Aeromonas caviae has been implicated in diarrhoeal disease of livestock and humans. The potential role of houseflies in the epidemiology of this pathogen was investigated by examining the prevalence of A. caviae in houseflies collected from two South Carolina farms and one restaurant. Isolation was accomplished by culture of flies in alkaline peptone water followed by identification with Aeromonas-specific PCR using novel primers (APW-PCR). All isolates cultured from houseflies were identified as A. caviae by biochemical characteristics and direct sequencing approximately 800 bp of the 16S rRNA gene. Aeromonas caviae was detected in 78% (272/349) dairy farm flies, 55% (54/99) pig farm flies and 39% (77/200) restaurant flies. Faeces from cows and pigs at the farms also were positive for A. caviae (58% and 100%, respectively). The APW PCR method provided a rapid, convenient way to identify A. caviae from faeces and houseflies that contained hundreds of bacterial species.

Molecular Basis of Bacterial Adhesion

Bacterial infections are responsible for a broad spectrum of human illnesses and medical device complications. For example, urinary tract infections caused by Escherichia coli affect over 7 million people annually and are among the most common infectious diseases acquired by humans.39 Enteropathogenic E. coli (EPEC) and shiga toxin-producing E. coli (STIC) are diarrhoegenic pathogens causing serious health problems in both industrialized and developing countries.26,15 Helicobacter pylori have been found to be a main factor in the development of gastric and duodenal ulcers and are believed to be a causitive factor of gastic cancer.34 Staphylococcus aureus and Staphylococcus epidermidis are major causes of infections associated with wounds, indwelling catheters, and cardiovascular and orthopedic implant devices.1,19,24,25,35,49,56,59

Amylolytic activity of Thermomonospora fusca

Amylases which produce maltotriose as the major end-product from starch are relatively rare. The thermophilic actinomycete, Thermomonospora fusca, produced an extracellular α-amylase which generated maltotriose as 61% of the identified products. The addition of maltotriose to a glucose-adapted exponential phase culture at 55°C in mineral salts medium caused rapid induction of amylase biosynthesis. Addition of glucose to cells growing on starch did not repress amylase biosynthesis because the actinomycete had a marked preference for maltotriose over glucose. The pH and temperature optima for the amylase activity of concentrated, washed extracellular protein were 6.0 and 65°C, respectively, with an energy of activation of 59kJ/mol. The thermostability of the concentrated, washed amylase was increased by the presence of its starch reaction products, but not by added Ca2+.

Bioremediation of compounds hazardous to health and the environment: An overview

Publisher Summary This chapter focuses on the fundamental microbial mechanisms (oxidative, reductive, and hydrolytic reactions) and associations in plant and microbial populations (competition, cross-feeding and commensalism), which may be essential to their success. Bioremediation of the chemicals in the soil depends on the activities of microbes in the soil, or in association with the root system. Chemical/physical properties of the chemical itself can influence the availability of the chemical to the microbe, or the susceptibility to degradative processes. Molecular alterations catalyzed by the microbial processes include oxidation, reduction, hydrolysis, de-esterification, dehalogenation, dealkylation, conjugation, and others. These processes usually result in a non-toxic chemical in the case of a pesticide, or in decreasing contamination levels of hazardous materials. Dissipation of pesticides in the soil involves several processes: volatilization, photodecomposition, leaching, adsorption, and microbial degradation. This chapter has been an overview of bioremediation processes, together with a few examples to illustrate the principles and efficacy of those processes.

Hydrolysis products inhibit adsorption of Trichoderma reesei C30 cellulases to protein-extracted lucerne fibres

Protein-extracted lucerne fibres (PELF) are an excellent lignocellulosic feedstock source in biomass conversion to the soluble sugars. PELF was hydrolysed (85% carbohydrate conversion in 48 h at 45°C) by the cellulase complex of Trichoderma reesei C30 cultured in an 85%(w/v) PELF-mineral salts medium. PELF hydrolysate inhibited binding of cellulase enzymes to fresh PELF; the binding of endoglucanase and exoglucanase components was inhibited an average of 27 and 46% respectively by an hydrolysate concentration of reducing sugars equivalent to 6% glucose. This inhibition must be considered in the development of any enzyme recycling system in which cellulases are recovered from the product stream by adsorption on fresh lignocellulosic material.

pH-dependent thermal activation of endo-1,4-β-glucanase in Thermomonospora curvata

Abstract The thermophilic actinomycete, Thermomonospora curvata, secretes a ceullulase complex capable of saccharifying crystalline cellulose. The saccharifying capacity of cell-free culture fluid was rapidly inactivated by heating at acidic pH, but at alkaline pH significant activation of the complex was effected by heat treatment. This pH-dependent thermal activation occurred in the major endoglucanase (endo-1,4-β- d -glucanase, EC 3.2.1.4) of the cellulase complex. Heating at 70°C, pH 8, resulted in about 50% activation of the endoglucanase in both crude and purified preparations. A thermal activation step may provide a cheap and rapid method for increasing the cellulolytic capacity of this actinomycete during industrial-scale biomass conversion processes.

Effects of the detergent Tween 80 on Thermomonospora curvata.

Tween 80 (0.1%, v/v) added to Thermomonospora curvata growing in minimal medium caused a transient lowering of the dry cell mass, decreased the optimal growth temperature of the thermophile from 62 to 54°C, and increased extracellular esterase activity. Cells grown in the presence of Tween 80 had decreased concentrations of branched chain fatty acids and increased concentrations of oleic acid. The detergent removed surface protuberances from mycelia and increased the liberation of enzymes active against crystalline cellulose, but did not stimulate liberation of enzymes active against carboxymethylcellulose, starch or pectin.

Thermostable fungal β-glucosidases

Remain and contemplate awhile Upon the noble thermophile, It bears its breast to searing heat Whilst lesser cells make fast retreat Despite that stress, it still is able To maintain its enzymes stable Through steam and stench, it reigns supreme In each heated niche of nature’s scheme Whether royal blue of boiling springs Or biomass of lowly and discarded things So, salute when you pass the compost pile Wherein reigns the noble thermophile . . .