Bacterial attack

This passes into the air above the liquid and dissolves in the film of water on the walls above the water level, where under the influence of aerobic bacteria, oxygen oxidizes it to H2SO4. The cement paste softens and the aggregate falls out. 

Preventive treatments have been of several kinds (L6). The sewage may be treated, e.g. with chlorine to oxidize the sulphides, with lime to raise the pH to above 10, which decreases the activity of the anaerobic bacteria, or with appropriate salts to precipitate the sulphide. Removal of slime and silt, in which the sulphide-forming reactions appear to occur, increase in How and design to avoid turbulence, have been found useful. The service life of the concrete is much increased by using limestone as opposed to siliceous aggregates. Various surface treatments have been used, of which one of the most effective appears to be with Sip4 gas. 

Other situations in which attack by H2SO4 formed through bacterial action has been reported include cooling towers (L6) and concrete floors laid on rocks containing pyrite (FeSj) (P58). 

---

Virtually all metallurgies can be attacked by corrosive bacteria. Cases of titanium corrosion are, however, rare. Copper alloys are not immune to bacterial attack however, corrosion morphologies on copper alloys are not well defined. Tubercles on carbon steel and common cast irons sometimes contain sulfate-reducing and acid-producing bacteria. Potentially corrosive anaerobic bacteria are often present beneath... 

The increase of restrictive regulations on the use of organic solvents favoured the increasing use of latex-based adhesives. Because of the slow evaporation of water, these adhesives show less tack and can suffer bacterial attack. Infrared heaters and ovens can be used to favour the evaporation of water. Often a small amount of solvent (coalescing aid) is added to the latex system to improve wetting and coalescence of the latex particles. 

A hydraulic fracturing fluid containing guar gum or other natural polymers can be stabilized against bacterial attack by adding heterocyclic sulfur... 

Heavy metals and to some extent their derivatives are among the indestructible pollutants that are neither subject to bacterial attack nor other breakdown or degradation processes and are thus permanent additions to the environment.12 14 Accordingly, their concentrations most often exceed the permissible levels normally found in the environment soil, water ways, and sediments, ending up in the food chains. Following these events, heavy metals and/or their derivatives accumulate in the plant and animal life where they profoundly disrupt biological processes, causing various... 

Most trading polymers contain a variety of additives, e.g., plasticisers, lubricants, stabilisers, etc., and it is these additives that promote bacterial attack on the polymer. At the same time, degradation by other routes provides pathways for bacterial attack by creating hydrophilic surfaces. Because many industrial and domestic services are supplied by underground plastic pipes and cables, care must be taken when choosing additives to make sure that the polymer is not vulnerable to attack. 

Residues of fatty acids from emulsion polymerisation and from cure activation provide sites for bacterial attack when the rubber product is exposed to warm moist conditions. The addition of a biocide/fimgicide will give excellent fungal growth protection. 

Preservatives (LD, DW, ADW, HC, FC) Guards against product aging by decay, discoloration, oxidation, and bacterial attack Ability to decrease water availability Butylated hydroxytoluene Ethylene diamine Glutaraldehyde 0.05-0.2% 0.05-0.2%... 

Bacterial attack is an early stage in the degradation of wood exposed in wet or moist conditions. Bacteria can be the dominant form of attack when fungal decay is suppressed by a wood-preserving treatment. Bacteria can attack the cell wall of wood by tunnelling, cavitation or erosion mechanisms (Eaton and Hale, 1993). 

Polyneuritis is a disorder of the peripheral nerves. It involves damage to the myelin sheath. The condition is due to inflammation of the axonal membrane caused by viral or bacterial attack, i.e. an antoimmnne disease. Guillain-Barre syndrome is one form of polynenritis and is an example of an autoimmune disease caused by immune mimicry in response to a bacterial or viral antigen. It is discnssed in Chapter 17. 

Ndumu et al. evaluated the effectiveness of Azadirachta indica seed oil against the larvae of this parasite [95]. They administered the oil as hydroalcoholic solutions ranging 4.2-100% and computed the mortality within 60 hours. Authors observed that the mortality of larvae was concentration and time dependent 100% mortality was observed with 100% pure neem oil after 48 h. The LD50 of different concentrations were 33.3% (56 h) and 66.7% (48 h). Author also observed little or no adverse effects on treated animals. Furthermore, they stated that the open wound caused by tick bites and therefore exposed to potential fungal and bacterial attacks, could be protected by the microbicidal properties of the neem oil. Previously, the effectiveness of neem oil was also observed by Williams and Mansingh against another tick species of the same genus, A. cajennense, another cattle tick [96]. 

Bacteriological Stability. The bacteriological stability provided by malo-lactic fermentation is its most important attribute. Wines aged before bottling (and which are susceptible to the fermentation) will nearly always be fermented during the first or second year. With proper post-fermentation treatment, these wines can be safely bottled without fear of further bacterial attack. We have seen no instances where a second bacterial fermentation has occurred once the malo-lactic fermentation was completed unless additions had been made to the wines or they had been blended. 

This study indicates that the sulfur of our sulfide samples was susceptible to bacterial attack in two of the three cases. The aliphatic sulfides could be ranked in the order of their ease of oxidation as di-ferf-butyl polysulfide > di-fert-butyl disulfide > di-tert-butyl sulfide. 

Treatment with Bacteria. Several years ago, it was discovered that the permeability of wood was increased by bacterial attack when logs were soaked in water for a period of time (45). Following this,... 

In pine, it was found that Bacillus polymyxa was the major species involved (45, 55), whereas, in spruce the major species were Bacillus subtilis and Flavobacterium pectinovorum (49). In another study (53), Clostridium omelianskii was identified as the species attacking softwoods. In all studies, it was found that the bacterial attack on the pit membranes was the reason for increased permeability of the wood. Furthermore, it was shown by Fogarty and Ward (49) that bacteria degraded the pit membranes by excreting the enzymes amylase xylanase, and pectinase. A typical sapwood pit membrane that has been attacked by bacteria is shown in Figure 2. As can be seen, the torus is severely degraded and has well defined openings. 

Mitchell, R. and Chet, I., Bacterial attack of corals in polluted seawater, Microb. Ecol., 2, 227, 1975. 

A modest but important use of certain tributyltin-contain-ing formulations is in hospital and veterinary disinfectants. Similar formulations are applied to protect textiles against fungal and bacterial attack, both in the industrial and the hygienic sector ("sanitizing"). 

Vinyl films, in addition to being protected against bacterial attack themselves, serve another and a growing function today. More and more... 

There still exists a series of further examples of the in vitro-activity of polymeric antibacterials, since such preparations are also applied as protection of polymeric materials against bacterial attack or as pesticides like a poly(methacryloyloxy phen-oxarsine) [25] 90). 

The PP materials are completely resistant to bacterial attack, are chemically inert, and are unaffected by water. Monofilaments can be produced that possess high strength, low elongation under stress, and dimensional stability at normal atmospheric temperatures. 

---