Bacteria and Algae

Hydrogen sulfide enters natural waters from decay of organic matter (e.g., in swamps), bacterial reduction of sulfate ion, or underground sour natural gas deposits. It can be removed by aeration, anion exchange (Eq. 14.14), or oxidation by chlorine to elemental sulfur  

Bacteria in water are usually thought of in terms of human disease. Indeed, until quite late in the nineteenth century, disastrous outbreaks of waterborne diseases such as cholera, dysentery, and typhoid fever were common in the major cities of the world. The last outbreak of typhoid in the United Kingdom occurred in Croydon in 1937. Serious cholera epidemics still occur in some parts of the world one that began in Peru in 1991 spread to several countries in the Americas, causing 391,000 cases of illness and 4000 deaths that year. 

Bacteria are also responsible for destruction of wood, for example in cooling towers, by breaking down the cellulose fibers. Certain bacteria derive their metabolic energy from the iron(II)-iron(III) redox cycle. These iron bacteria can proliferate to the extent that they block pipes. In any case, they will discolor water. In addition, objectionable growths of algae can occur in water tanks or circuits, given even minimal supplies of nutrients. Consequently, biocidal agents are widely used in the treatment of industrial, as well as municipal, water supplies. 

Aqueous chlorine, however, reacts with other possible solutes such as HaS (Eq. 14.25), NH3 (giving chloramine, NH2CI), and organic matter, so the chlorination plant operator arranges for 0.2 to 0.5 ppm chlorine equivalent to remain in the water 5 minutes after treatment, as this is enough for continued bactericidal action en route to the user. 

Chlorination can result in unacceptable taste intensification, where potable water is concerned. This often originates in the chlorination of phenols present in trace amounts from industrial pollution. If economics permit, use of chlorine dioxide (Section 12.2) or ozone (Section 8.3) in place of chlorine will minimize taste intensification and will also avoid formation of carcinogenic chlorocarbons, notably chloroform. These carcinogens may form from chlorination of contaminants such as acetone, a commonly used solvent that finds its way into water supplies  

---

Bioflocculation The clumping together of fine, dispersed organic particles by the action of certain bacteria and algae. 

Plants (particularly seedlings, which cannot yet accomplish efficient photosynthesis), as well as some bacteria and algae, can use acetate as the only source of carbon for all the carbon compounds they produce. Although we saw that the TCA cycle can supply intermediates for some biosynthetic processes, the... 

Unicelluar algal and bacterial genes were the first to be isolated and characterized and led to the isolation of most of the higher plant genes involved in carotenoid biosynthesis. Carotenogenic gene clusters from bacteria and algae" - - - contributed immensely to the elucidation of the carotenoid pathway. 

Bott, T.L., Standley, L.J. (2000) Transfer of benzo[a]pyrene and 2,2,5,5,-tetrachlorobiphenyl from bacteria and algae to sediment-associated freshwater invertebrates. Environ. Sci. Technol. 34, 4936 -942. 

Amsler CD, Iken KB (2001) Chemokinesis and chemotaxis in marine bacteria and algae. In McClintock JB, Baker BJ (eds) Marine Chemical Ecology. CRC Press, Boca Raton, Florida,... 

Ostracods 0 98 000 6000 Stimulated by factors that increase primary production, such as N and P fertilizer. Filter bacteria and algae from water... 

The molecular weight of these proteins ranges from 14,000 to 23,000 as shown in Table 2. Organisms which have been reported to produce flavoproteins include several species of bacteria and alga. However, unlike the case with ferredoxins, these proteins have not yet been found in higher plants and animals. 

Phosphates are also problematic. Most phosphates are present in residential water as inorganic phosphates, but organic moieties are common. Biological action converts the various forms into orthophosphates that can be removed from water streams by incorporation into specialized bacteria and algae. 

Light-driven electron transfer in plant chloroplasts during photosynthesis is accomplished by multienzyme systems in the thylakoid membrane. Our current picture of photosynthetic mechanisms is a composite, drawn from studies of plant chloroplasts and a variety of bacteria and algae. Determination of the molecular structures of bacterial photosynthetic complexes (by x-ray crystallography) has given us a much improved understanding of the molecular events in photosynthesis in general. 

Many cytochromes c are soluble but others are bound to membranes or to other proteins. A well-studied tetraheme protein binds to the reaction centers of many purple and green bacteria and transfers electrons to those photosynthetic centers.118 120 Cytochrome c2 plays a similar role in Rhodobacter, forming a complex of known three-dimensional structure.121 Additional cytochromes participate in both cyclic and noncyclic electron transport in photosynthetic bacteria and algae (see Chapter 23).120,122 124 Some bacterial membranes as well as those of mitochondria contain a cytochrome bct complex whose structure is shown in Fig. 18-8.125,126... 

Incubation of lake water with 32P or 33P as tracers and subsequent gel chromatography reveals that a major pathway exists between dissolved orthophosphate and the particulate phase (3, 5-7). Low-molecular-weight phosphorus forms in the presence of bacteria and algae. SUP is present in the low-molecular-weight fraction and is classified as individual DOP compounds unassociated with particulate or colloidal material. The HMW fraction found in gel chromatography studies is characterized as a colloid that contains phosphorus compounds or incorporates orthophosphate. The colloidal material then releases orthophosphate, replenishing the dissolved phosphorus cycle. In some eutrophic lakes the HMW SRP fraction can make... 

Sulfate Reduction. Dissimilatory sulfate reduction, anaerobic respiration with sulfate as the terminal electron acceptor, is performed by relatively few genera of bacteria (84). Many bacteria and algae are able to... 

Nitrogen fixation by some bacteria and algae, e.g., Klebsiella, Azotobacter, Nitrifying Rhizobium... 

Many water sources can also contain considerable microbiological organisms, especially bacteria and algae, which can add to the problems encountered. 

As summarized by Cassell et al. (ref. 36), the early work on microflotation described the removal of bacteria and algae from water (ref. 61, 62) thereafter, further studies demonstrated that B. cereus (ref. 63), colloidal constituents of tea (ref. 64), humic acid (ref. 65), colloidal silica (ref. 66), illite (ref. 67), titanium dioxide (ref. 68), and polystyrene latex (ref. 69) could be rapidly and efficiently removed from water by microflotation. The general variety of dispersed materials which have been separated successfully... 

A.J. Rubin, E.A. Cassell, O. Henderson, J.D. Johnson and J.C. Lamb, Microflotation new low gas flow rate foam separation technique for bacteria and algae, Biotech Bioengng. 8 (1966) 135-150. 

Macromolecules such as exopolysaccharides and humic condensates affect the distribution of microorganisms and nutrients within the water column by adding microstructure. Many planktonic bacteria and algae secrete polysaccharides. In some circumstances, exopolysaccharide production is a substantial portion of gross production. The adaptive significance of this activity is unclear. Possibilities include the dumping of excess photosynthate,... 

---