Mycotoxins, Wood Decay, Plant Stress, Biocorrosion, and General Biodeterioration

A variety of extracellular polysaccharidases produced by brown-rot fungi are thought to play an important role in the wood-rotting process. There is evidence of early removal of hemicellulose, a principal cell wall constituent, by hemicellulases (xylanases, mannanases), which attack and shorten hemicellulose chains sufficiently for further hydrolysis by glycosidases into simple sugars, thus facilitating colonization and penetration of wood (Kirk and Highley, 1973; Kirk and Cowling, 1984; Highley, 1987). The enzyme b-1,4—xylanase, of the brown-rot fungus Postia placenta (Fr.) M. Lars. et Lomb. MAD 698, has been partially purified (Green et al., 1989b) and used as antigen to produce monoclonal antibodies. This glycoprotein typically co-migrates with carboxymethyl-cellulase and has been comprised of as much as 50 percent carbohydrate when extracted from wood.

Benko (1988a,b) studied the suitability of several bacteria as biological control agents for preventing discoloration and deterioration of wood by sapwood-inhabiting fungi. In a study by Highley et al. (1991), metabolites produced by Streptomyces rimosus were effective in controlling sapwood-inhabiting fungi. The unconcentrated metabolites inhibited spore germination of all the sapwood-inhabiting fungi tested and prevented discoloration of pine blocks. However, Penicillium and Aureobasidium pullulans were able to attack sweetgum blocks treated with the metabolites.

The most destructive form of wood decay, brown rot, is caused by a relatively small number of species of Hvmenomycetous basidiomvcetes. These basidiomycetes are unique among cellulose destroyers because they are the only known microbes that can degrade the cellulose in wood without first removing the lignin (Cowling, 1961; Liese, 1970). Brown-rot fungi leave a brown residue—hence their name—that has been partially o-demethylated (Kirk, 1975). Furthermore, brown-rot fungi degrade cellulose in an unusual manner that differs from that of other cellulolytic organisms. Hyphae of these ubiquitous fungi invade wood cells and bring about a rapid depolymerization of the cellulose with low losses in total wood substance (Cowling, 1961; Kayama, 1962b). The average number of glucosyl residues per cellulose molecule (degree of polymerization, DP) is thereby reduced from about 104 (Goring and Timell, 1962) to about 200 (Cowling, 1961). The resulting fragments correspond to the size of the cellulose “crystallites.” This effect is thought to be brought about by cleavages within the amorphous regions of the cellulose that separate the crystallites (Cowling, 1961). Similar depolymerization of cellulose to the “limit DP” (to the crystallites) is effected by acid hydrolysis (Battista, 1950) and by chemical oxidants (Koenigs, 1972a, 1974a,b, 1975; Highley, 1977; Kirk et al., 1991). As a result of the initial attack by brown-rot fungi and the depolymerization of the cellulose, wood strength collapses. How this rapid depolymerization occurs is a perplexing biochemical question: as Cowling and Brown (1969) recognized over two decades ago, even the smallest cellulases (approximate diameter 25 _, length 140 _) are too large to penetrate the pores of wood (median pore diameter approximately 10 _; maximum 35–100 J. Also, cellulases do not mimic the action of brown-rot fungi in generating cellulose crystallites (Chang et al., 1981; Phillip et al., 1981). Our own examination of the change in pore structure of wood as it is decayed by a brown-rot fungus suggests that the depolymerizing agent is between 12 and 38 in diameter (Flournoy, 1991; Flournoy et al., 1991).

Using biological controls to protect wood against fungal attack is an attractive alternative to chemical biocides because of their environmental effects. Much research on biological control of wood-attacking fungi has involved Trichoderma spp. and, to a lesser extent, Scvtalidium spp. (Freitag et al., 1991). Laboratory studies of antagonism between Trichoderma, Scvtalidium. and wood decay fungi have been promising, but field studies have met with mixed results.

Control of biodegradation is an ongoing problem in ecologically sensitive areas, requiring new approaches to deter degrading organisms. Biological control is an approach that takes advantage of the ecological relationship among organisms by using natural predators against degrading organisms. This approach has led to an interest in using predator metabolites as pesticides.

Pine cones, a renewable resource, are not used to their potential. Large quantities of cones are produced annually throughout the world, especially in pine plantations grown for the pulp and paper industry. They are collected, dried to facilitate seed release, and generally discarded. Some nurseries grind the cones into mulch or they may be sold for crafts, but consumer demand for cones is small compared to by-products from other industries. New uses for pine cones could provide additional income for forest landowners.

Coriolus versicolor, a white-rot Basidiomycete, secretes cellulolytic and ligninolytic enzymes (Higuchi, 1953; Rosenberg, 1979; Harvey et al., 1987) as well as polyphenol oxidase (Taylor et al., 1987; Moore et al., 1989). Whereas the former degrade certain wood polymers (Higuchi, 1985), the latter can convert o-diphenols to o-diquinones (Fric, 1976) and oligomerize syringic acid (Liu et al., 1981), a lignin derivative. In this connection, certain phenolic compounds can serve as disease-resistance factors possibly regulating the proliferation of wood-decay fungi within host tissues (Shigo, 1984; Dashek et al., 1990). Because ligno-cellulolytic enzymes are of commercial value to the paper-pulp industry (Zadrazil and Reiniger, 1988) and the agricultural community (Van der Meer et al., 1987), an inexpensive and “readily-available” supply of these enzymes is highly desirable. As C. versicolor can be “batch-cultured”, over-production and enhanced secretion of these enzymes are feasible (Fahraeus and Reinhammer, 1967). While over-production could possibly be achieved by substrate induction and/or recombinant DNA technologies (Maniatis et al., 1982), secretion might be enhanced by controlling cellular energy gradients and/or possible glycosylation of PPO.

Numerous studies of the fungal decay of wood have been conducted, especially in the past few decades. The major motivation in the search to understand wood decay is the potential application of research results in essentially two areas: (1) decay protection of wood and wood products in use and (2) biological processing of wood for the production of pulp for paper manufacture, pulp bleaching, and effluent treatments.

Ozone (O₃) is normally present within the earth’s troposphere at 20–30ppb concentration. However, as a result of increased industrialization and urbanization, e.g., automobile emissions (Elstner, 1984), O₃ has become an undesirable atmospheric pollutant in many densely-populated areas of the United States. However, monitoring of atmospheric O₃ at the Coweeta Hydrologic Laboratory (Otto, NC) during 1988 revealed April through September fluctuations of 40–70 ppb (Figure 1), and mean hourly concentrations sometimes exceed 90 ppb. Thus, even rural areas experience elevated atmospheric O₃ levels, presumably as a result of long-range transport of ozone precursors (e.g., NO_x).

Loblolly pine is the most important forest tree species in the Southeastern United States, producing the major volume of both commercial timber and pulpwood for the region. Inadequate regeneration of this species has been identified as one of the causes of lower yields of softwood in the Southeast. Part of the solution would be a readily available seed supply for forest nurseries. In the mid 1950’s, an intensive program was initiated to produce genetically improved seeds from loblolly pine for reforestation of harvested stands. Scions from superior phenotypes in natural stands were grafted onto seedlings and clonal seed orchards were established (Zobel et al., 1958). Even with substantial insect and disease protection, annual seed losses are observed. Any seed loss has an economic effect because of the high value of the genetically improved seed. The objective of the present investigation was to evaluate seed production efficiency in the Georgia Forestry Commission’s Arrowhead Seed Orchard, Pulaski County, Georgia. Here, we report data regarding analysis of cones collected from clones in the seed orchard. Analysis of 21 sample trees revealed that two clones, 558 and 593, were the most productive based upon seed efficiency data. In some ovules, the deterioration of the ovular contents began in June and resulted in the production of “empty seeds”.

Contamination of surface water by conglomerate mixtures of metals is a significant health problem in aquatic environments near mining and metal (tannery) processing operations. Metals, such as hexavalent chromium (CrVI), manganese (Mn), lead (Pb), selenium (Se), and zinc (Zn) have been shown to occur at elevated levels in many near-shore environments (Capone et al., 1983). In situ bioremediation of these metals has been suggested as a mechanism to alleviate the presence of these contaminants. In this regard, our laboratory has examined the bioremediation and removal of various individual heavy metals from soil and water, in simulated ponds using a mixed microbial ecosystem. In these experiments 80–90% of the metals examined were reduced and recovered from both soil and water in the biomass formed on the pond surface (Ibeanusi et al., 1989; Archibold et al., 1989; Bender et al, 1987).

Dracunculiasis is one of the oldest parasitic diseases known to man, and currently affects approximately 50 millon people in Africa, India and the middle east (Hopkins, 19911. The disease is commonly referred to as guinea worm disease. Recently, there have been more concerted efforts to control the disease; and more attention directed towards many ways of controlling its economic impact in various countries (Hopkins, 1991). While the mortality rate is low, the disease’s socio-economic impact is probably greater than that of many fatal infections. The alleviation of this disease will result in a dramatic improvement in the health and agricultural productivity and general well-being of millions of affected people in endemic areas of the developing world.

Urinary schistosomiasis, a water-born parasitic infection is a debilitating disease of great importance in most parts of developing countries (Hatz, 1990). Studies have shown that the disease is endemic in Nigeria and that its epidemiological patterns vary from one part of the country to another (Pugh and Giles, 1979; Ejeize and Ade-Seramo, 1982; Arene et al., 1966; Adekolu John and Abolarin, 1986).

Humans infected with African trypanosomes develop severe neurological and neuropsychiatric disturbances during the terminal stages of the disease (Lambo, 1966; WHO report, 1985) and the mechanisms causing these disturbances are not known. Currently, much attention is focused on the possible biochemical basis for these disturbances (Tanowitz et al., 1981, 1983; Brennessel et al., 1985). These investigators reported that some alterations of enzyme activity in the central nervous system may play a role in the pathogenesis. Acetylcholinesterase (AChE) is an enzyme found in the cholinergic synapses and neuromuscular junctions of various mammalian tissues. We postulate that AChE levels in infected brains of rabbits with Trvpanosoma brucei brucei may be directly or indirectly related to cerebral symptoms in animals and possibly humans. Thus, the objective of this investigation was to study AChE activity in the brains of rabbits infected with T. brucei brucei.

The ciliate, Tetrahymena pyriformis, has been of major importance to scientific inquiry since its successful growth as axenic cultures in 1922 (Hill, 1972). The pear-shaped fresh water protozoan has been referred to as the “Escherichia coli” of the non-photosynthetic eukaryotes (Elliott, 1973), much more than the classical Paramecium. Tetrahvmena has been widely accepted as a research model for studies in genetics, biochemistry, endocrinology and toxicology. Cell and developmental biologists have enjoyed a lasting relationship with Tetrahvmena as a result of its remarkable resemblance in structure and function to a typical cell.

Myiasis has been defined as the invasion of living vertebrate tissue by the larvae of certain species of Diptera (Vasallo, 1991). The infection has a cosmopolitan distribution. Only few cases of the disease have been reported in African subregions (Dipeolu and Olufarati, 1975; Ogunniyi, 1981; Edungbola, 1982; Lyko and Mutinga, 1988).

In February 1874 a party of six gold miners set off from an Ute Indian camp near the present city of Delta, Colorado. They were bound east into the San Juan Mountains to the Los Piños Indian Agency (Figure 1). Only Alferd Packer completed the journey. According to his harrowing account, the other members of the party died of starvation or were killed when they attacked other members of the group. Packer admitted to killing one member of the party in self-defense; he also admitted surviving by eating flesh from the dead. In August 1874 an artist for Harper’s Weekly came upon five mutilated bodies near the Lake Fork of the Gunnison River. Following an inquest held on the spot, a warrant was issued for Packer’s arrest.

Forensic scientists are frequently called upon to examine minute bits of physical evidence that may be transferred between a criminal and the scene of his crime or the criminal and his victim. These minute bits of evidence are referred to as trace evidence. They are used to associate a suspect in a criminal case with a particular crime. Trace evidence includes glass particles, soil, paint chips and smears, textile fibers and hairs.

There are several methods of analysis available for detection of delta-9-tetrahydrocannabinol (delta-9-THC), a biologically active component of marihuana derived from Cannabis sativa L. These range from simple colorimetric tests (Beam 1911) to the Duquenois-Levine reaction which replaced the Beam test (Hahas, 1975). Analytical laboratories having available to them gas chromatography instrumentation utilize the procedures of Lerner (1986), Fetterman et al. (1971), Turner and Hadley (1973), or the DEA (1976) method when small quantities of material are evaluated.

Introduction with Cannabis, one of the oldest drugs known to man, is now widespread over the world, including Western countries where it had never been observed before. Cannabis sativa has been cultivated for centuries for the hemp in its stem, the oil in its seed, and the biologically active substance in its flowering tops. The principal biologically active ingredients include delta-9-tetrahydrocannabinol (delta-9-THC) (Nahas, 1975).

Bacterial indicators of water quality have been developed over previous decades as tools to be used in decision-making processes for the protection of public health. These indicators serve the purpose of relating the degree of risk that a particular body of water holds regarding human contact, to the ingestion of the water or consumption of food species taken from the water. For the most part, they only suggest that pathogenic organisms may be present. In total, all of these can be considered “aquatic toxicants as biodeteriogens affecting human health.” If present in high numbers the water may be judged to be unfit for its designated use. Nevertheless, no indicator group in use today can yield information with absolute certainty as to the sanitary quality of the water. To complicate matters further, there are several criteria and/or standards for assessing fresh water and marine water quality, depending on specific preestablished uses.

Corrosion by sulfate-reducing bacteria (SRB) has been intensively studied during the last 40 years, but until now the importance of oxygen in SRB-related corrosion has rarely been emphasized (Hardy and Bown, 1984; Starkey, 1985; Hamilton, 1990; Hamilton, 1991). The impact of oxygen on SRB-related corrosion is attributed to a direct effect on the sulfur-related corrosion products rather than to any stimulation of SRB activity (Hamilton, 1990; Hamilton, 1991). Pitting corrosion is the characteristic mode of attack and deep pit is usually found underneath a porous corrosion products. However, the role that oxygen plays in the aerobic/anaerobic environments in relation to corrosion has not been clearly defined. The system is complex and dynamic. The role of SRB must be viewed in the context of biological consortia (biofilms) and/or mixed ecosystems. In addition to the biological factors, the chemical environments which influence corrosion are also complicated by the introduction of oxygen. The following statement is quoted from Starkey. “ Factors that have been suggested or may be concerned with anaerobic corrosion relate particularly to the effect of ferrous sulfide, sulfur, ferrous hydrate and all other products of the corrosion process, differential aeration cells, and various combinations of all of those factors”. In this review, we intended to focus on aspects of experimental systems that more accurately reflect those environmental conditions generally associated with corrosion in the field. Describing the role of dissolved oxygen on SRB-related corrosion, we will summarize the current published papers which describe the corrosion of mild steel underneath aerobic biofilms containing SRB (Lee and Characklis, 1990; Lee et al. 1992). Finally, we will discuss various experimental approaches in an attemp to elucidate the true mechanism of SRB-related corrosion in aerobic environments.

Stainless steels (SS) are frequently used in a variety of industrial applications, where good corrosion resistance is needed. SS are usually in contact with waters of very dissimilar nature that generally, are favorable environments for microbial growth. Thus, they are susceptible to microbiologically influenced corrosion MIC (Pope et al., 1989).

The purpose of this paper is to present a brief review of how microbial fouling films affect the corrosion behavior of passive metals and alloys in fresh, brackish and sea waters. It has often been reported that microbial films change the open circuit corrosion potential (OCP) of passive metals immersed in natural waters (Mollica and Travis, 1976; Johnsen and Bardal, 1985, 1986; Scotto, et al., 1985; Dexter and Gao, 1988; Gallagher, et al., 1988; Scotto, 1989). The change has usually been in the noble (electropositive) direction, and it has been called, “ennoblement.” The significance of this effect lies in it’s influence on localized corrosion initiation and propagation. In chloride bearing waters, the initiation of pitting and crevice corrosion is statistical, with the probability of initiation increasing directly with chloride ion activity and OCP. Thus, at a given chloride level, the probability of localized corrosion initiation is increased by anything (such as a biofilm and its metabolic products) that causes the OCP to shift in the noble direction.

An industrial plant contains several environments where corrosion and fouling processes are potentially troublesome, such as cooling water systems, storage tanks, water and wastewater treatment facilities and piping (Characklis, 1986). Corrosion is one of the undesirable results of fouling, in addition to energy losses owing to increased heat transfer and frictional resistances. A recirculating cooling water system provides a good example of an industrial environment where corrosion and fouling hazard is particularly critical and needs to be kept under strict control.

Microbial geochemical cycles have been going on since life on earth began. This activity results in chemical and mineralogical modification of the different types of rocks and minerals within the biosphere and involves essentially the solubilization processes of major mineral elements from silicates, carbonates, phosphates, oxides, etc. While the weathering of minerals in natural environments results in the destruction of rocks, thus contributing to soil formation processes, it has a deleterious effect when these rocks are part of historic buildings and monuments.

Monoamine oxidase (MAO) is postulated to play an important role in controlling the levels of certain neurohormones and other pharmacologically important amines (Schacht and Leven, 1977; Von Korff, 1979). This involvement has stimulated considerable interest in the physiochemical and enzymatic properties of the enzyme.

The role of Plasma Amine Oxidase (diamino: O₂ oxidoreductase; EC 1.4.3.6) in the catabolism of various amines found in association with DNA and its function in one of the catabolic pathways of histamine and other pharmacologically important amines have led to considerable interest in this enzyme. The enzyme catalyzes the oxidation of certain amines and diamines according to the following reaction: % MathType!MTEF!2!1!+- % feaagCart1ev2aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamOuaiaado % eacaWGibWaaSbaaSqaaiaaikdaaeqaaOGaamOtaiaadIeadaWgaaWc % baGaaGOmaaqabaGccqGHRaWkcaWGpbWaaSbaaSqaaiaaikdaaeqaaO % Gaey4kaSIaamisamaaBaaaleaacaaIYaaabeaakiaad+eacqGHsisl % cqGHsislcqGHsislcqGHsislcqGHsislcaWGsbGaam4qaiaadIeaca % WGpbGaey4kaSIaamOtaiaadIeadaWgaaWcbaGaaG4maaqabaGccqGH % RaWkcaWGibWaaSbaaSqaaiaaikdaaeqaaOGaam4tamaaBaaaleaaca % aIYaaabeaaaaa!51B4!$$RC{H_2}N{H_2} + {O_2} + {H_2}O - - - - - RCHO + N{H_3} + {H_2}{O_2}$$ Physicochemical studies of bovine plasma amine oxidase indicated that the enzyme is made up of two identical subunits and has a molecular weight of 170,000 KD (Yasunobu et al., 1976). The enzyme contains one essential histidine residue per monomer (Hiramatsu, et al., 1975). There are two gram-atom Cu/ mole protein which are essential for enzyme activity (Yasunobu et al., 1976). It has been reported that the copper does not change its valence state during catalysis either under aerobic or anaerobic addition of substrate. The only variance to the no valence change was the work reported by Mondovi et al., 1976 who reported that copper changed its valence state during substrate oxidation. It was concluded acid analysis was performed on the native enzyme and the reduced modified enzyme. The concentration of the protein was determined by a biuret method and absorbance was read at 280nm (R = 13). N-(1-pyrene) maleimide was purchased from Molecular Probes. The other common reagents used were of reagent grade and were purchased from standard companies.

Clostridium difficile, the primary cause of pseudomembranous colitis (PMC) in humans, produces two toxins; toxin A, an hemorrhagic enterotoxin and toxin B, a potent cytotoxin. Both toxin proteins appear to act synergistically to induce colitis and PMC. Size estimates of the toxin proteins have varied widely; however recent DNA sequence information estimated the size of toxin A to be 307,972 daltons (Dove et al. 1990 4 and toxin B to be 269,696 daltons (Barroso et al. 1990). These large bio-toxins are only found in pathogenic strains of C. difficile but not found in non-pathogenic strains. In addition to the studies of the toxin proteins, a number of labs have been investigating the molecular biology of these toxin genes.

The objective herein is to provide the conceptual basis as well as some specifics needed in the development of a mycology laboratory. It is acknowledged that physical constraints and fiscal limitations would have major effects on the development of an ideal mycology laboratory. However, it is possible, over several years, to plan and then gradually develop such a physical facility without the need for an immediate and substantial fiscal out-lay. It must be noted that substantial initial start-up funds for the development of such a laboratory would be needed if there is no physical facility currently in place or an building/area capable of being modified. At times, building modifications may be more expensive and have inherent restrictions which could make the additional cost for a new facility more palatable. Also, a new building offers numerous advantages in design and resultant quality of the laboratories housed therein. Certainly the mycology laboratory will be tied to the other laboratories and the facilities available, but creativity, planning, and flexibility can be exercised so that the mycology component is suitably functional and a quality laboratory.

Copper (Cu) is required in the diet as a trace mineral to prevent hypochromic microcytic anemia secondary to defective hemoglobin synthesis (Hart et al., 1928). This metal is also required for the normal function of a number of oxidative enzymes including catalase, peroxidase, and cytochrome oxidase. Following absorption from the gastrointestinal tract, copper is weakly bound to albumin and later more firmly bound to ceruloplasim, a specific Cu transport protein (Linder and Moor, 1977). Bile is the normal excretory route for copper and plays a primary role in copper homeostasis while liver and bone normally store excess copper.