Dynamics of pollution-indicator and heterotrophic bacteria in sewage treatment lagoons

The spatio-temporal dynamics of pollution-indicator bacteria and aerobic heterotrophic bacteria were studied in the sewage treatment lagoons of an urban wastewater center after 26 months of biweekly sampling at eight stations in these lagoons. Robust statistical methods of time-series analysis were used to study successional steps (through chronological clustering) and rhythmic behavior through time (through contingency periodogram). The aerobic heterotrophic bacterial community showed two types of temporal evolution: in the first four stations, it seems mainly controlled by the nutrient support capacity of the sewage input, whereas in the remaining part of the lagoon, it seems likely that the pollution-indicator bacteria are gradually replaced by other bacterial types that are better adapted to this environment. On the other hand, the pollution-indicator bacteria showed an annual cycle which increased in amplitude at distances further from the wastewater source. The main events in this cycle were produced simultaneously at all stations, indicating control of these bacterial populations by climatic factors, which act through physical and chemical factors, and also through other biological components of this ecosystem (phytoplankton and zooplankton). Finally, we use results from this study to suggest a modified design for a future study program.     

Occurrence of multiple-antibiotic-resistant enteric bacteria in domestic sewage and oxidation lagoons.

The coliform bacterial population in the Grand Forks, N.Dak. sewage system was examined for multiple-antibiotic-resistant organisms over a 1-year period. Multiple-antibiotic-resistant coliforms were found to be common in the sewage, and their numbers remained fairly constant relative to the total coliform population throughout the year. Resistance to kanamycin, tetracycline, and ampicillin was found to be transferable at variable rates. Transfer rates were found to be temperature sensitive and were optimal at 35 degrees C. Although 75% of the multiple-antibiotic-resistant coliforms were capable of transferring resistance at some level, only 25% were capable of transferring resistance at rates greater than 10(-3) transconjugants per initial donor.     

Occurrence of multiple-antibiotic-resistant enteric bacteria in domestic sewage and oxidation lagoons

The coliform bacterial population in the Grand Forks, N.Dak. sewage system was examined for multiple-antibiotic-resistant organisms over a 1-year period. Multiple-antibiotic-resistant coliforms were found to be common in the sewage, and their numbers remained fairly constant relative to the total coliform population throughout the year. Resistance to kanamycin, tetracycline, and ampicillin was found to be transferable at variable rates. Transfer rates were found to be temperature sensitive and were optimal at 35 degrees C. Although 75% of the multiple-antibiotic-resistant coliforms were capable of transferring resistance at some level, only 25% were capable of transferring resistance at rates greater than 10(-3) transconjugants per initial donor.     

Nitrogen-fixing heterotrophic bacteria and presumptive coliforms in sewage treatment plants and irrigation reservoirs in Libya

Monitoring of heterotrophic nitrogen-fixing bacteria and presumptive coliforms in two Libyan sewage treatment plants showed that tertiary treatment of effluents by chlorination killed these bacteria. However, the irrigation reservoirs which received the treated effluent contained large numbers of both types of bacteria. As the proportion of nitrogen-fixers to presumptive coliforms was much less in the sewage than in the irrigation reservoirs it is probable that the irrigation water became contaminated by a source other than sewage.     

Phototrophic purple and green bacteria in a sewage treatment plant.

In all purification stages of a biological sewage treatment plant, phototrophic bacteria were detected by the method of viable cell counts. The predominant species identified belonged to the genus Rhodopseudomonas of purple nonsulfur bacteria. The number of phototrophic bacteria was highest in wastewater containing sludge. In activated sludge, an average of 10(5) viable cells/ml was found; the number depended upon concentration of sludge rather than on seasonal changes in light conditions in the course of a year. Bacteriochlorophyll a was extracted from activated sludge. Relative to the viable counts of phototrophic bacteria, the content of bacteriochlorophyll a was 5- to 10-fold higher than that of three representative pure cultures. By incubation of activated and digester sludge under different environmental conditions, it was shown that phototrophic bacteria can complete with other bacteria only under anaerobic conditions in the light.     

Oligotrophic properties of heterotrophic bacteria and in situ heterotrophic activity in pelagic seawates

Abstract The distribution of heterotrophic bacteria in polluted coastal and unpolluted pelagic seawaters was studied using a ¹⁴C-MPN method with either five of seven kinds of ¹⁴C-organic compounds as substrates. The total number of heterotrophic bacteria in pelagic waters ranged from 9.2 × 10³ to 5.4. ¢ 10⁴ cell/ml and more than 85% of the heterotrophic bacteria were represented by obligate oligotrophs. In coastal waters, the number of heterotrophs was one order of magnitude higher (av. 3.5 ¢ 10⁵ cells/ml), and eutrophic and facultatively oligotrophic bacteria were predominant. Oligotrophs in pelagic waters had a high specificity for the utilization of amino acids, especially glycine, and acetate-utilizing bacteria were scarce. The in situ maximum uptake rates of glutamate and glycine were much higher than those of glycolate and acetate. Acetate uptake rates were extremely low or not detectable in pelagic waters. The specificity of uptake kinetics is assumed to depend on the existence of obligate oligotrophs as dominant bacteria in pelagic seawater.     

Free-living bacteria and potential bacterial pathogens in sewage treatment plants

Applied Microbiology and Biotechnology - To comprehensively understand the profile of free-living bacteria and potential bacterial pathogens in sewage treatment plants (STPs), this study applied...     

Some properties of methylotrophic bacteria isolated from sewage sludges derived from mechanical and biological sewage treatment plants.

The presented studies were carried out to get more information about physiological properties of methylotrophic bacteria selected from sewage sludges derived from mechanical and biological sewage treatment plants. All the isolated bacterial strains belonged to facultative methylotrophs. The majority of them utilized glucose, starch and lipids. Moreover, most of them were also found to possess proteolytic properties and were able to hydrolyze urea but they were incapable of asparagine ammonification.     

Effect of temperature on mineralization by heterotrophic bacteria.

When pure cultures of the bacteria Pseudomonas fluorescens (a psychrotroph), Escherichia coli (a mesophile), and SRL 261 (a thermophile) were shifted away from temperatures to which they were adapted, the percentage of substrate mineralized increased (percent mineralized = [substrate respired to CO2]/substrate respired to CO2 + substrate incorporated into biomass] X 100). The increase in the percent mineralized was larger for larger temperature shifts. Similar responses were observed when natural heterotrophic bacterial populations from sediments of Lake George, N.Y., and a thermophilic algal-bacterial mat community at the Savannah River Plant, Aiken, S.C., were subjected to temperature shifts. These results suggest that an increase in the percent mineralized may be an indication of thermal stress in bacterial populations.     

Distribution of heterotrophic bacteria in Shira lake

The study of the horizontal and vertical distribution of heterotrophic bacteria in brackish Lake Shira in summer periods showed that mesophilic bacteria dominated in all areas of the lake, whereas psychrotolerant bacteria dominated in the metalimnion and hypolimnion of its central part. Nonhalophilic bacteria were mostly mesophilic and dominated in coastal waters. Most psychrotolerant bacteria were able to grow in the presence of 5-10% NaCl. Heterotrophic bacteria isolated in different regions of the lake were identified to a generic level. The isolates were classified into autochthonous and allochthonous microorganisms on the bases of their distribution pattern in the lake water, halotolerance, and ability to grow at low temperatures.     

Interactions between heterotrophic plate count bacteria and coliform organisms.

Studies were initiated to investigate the interactions between heterotrophic plate count bacteria and coliform organisms. We used spiked samples to show that heterotrophic plate count bacteria could reduce coliform densities by more than 3 logs within 8 days. Some heterotrophic plate count bacteria were able to cause injury to the coliform population. A significant correlation (r = 0.66; P less than 0.05) was observed between the initial level of heterotrophic plate count bacteria and the rate of coliform decline. Competition for limiting organic carbon was hypothesized to be responsible for the observed effects.     

Feeding and grazing impact by small marine heterotrophic dinoflagellates on heterotrophic bacteria

ABSTRACT. We investigated the feeding of the small heterotrophic dinoflagellates (HTDs) Oxyrrhis marina , Gyrodinium cf. guttula , Gyrodinium sp., Pfiesteria piscicida , and Protoperidinium bipes on marine heterotrophic bacteria. To investigate whether they are able to feed on bacteria, we observed the protoplasm of target heterotrophic dinoflagellate cells under an epifluorescence microscope and transmission electron microscope. In addition, we measured ingestion rates of the dominant heterotrophic dinoflagellate, Gyrodinium spp., on natural populations of marine bacteria (mostly heterotrophic bacteria) in Masan Bay, Korea in 2006–2007. Furthermore, we measured the ingestion rates of O. marina , G . cf. guttula , and P. piscicida on bacteria as a function of bacterial concentration under laboratory conditions. All HTDs tested were able to feed on a single bacterium. Oxyrrhis marina and Gyrodinium spp. intercepted and then ingested a single bacterial cell in feeding currents that were generated by the flagella of the predators. During the field experiments, the ingestion rates and grazing coefficients of Gyrodinium spp. on natural populations of bacteria were 14–61 bacteria/dinoflagellate/h and 0.003–0.972 day⁻¹, respectively. With increasing prey concentration, the ingestion rates of O. marina , G . cf. guttula , and P. piscicida on bacteria increased rapidly at prey concentrations of ca 0.7–2.2 × 10⁶ cells/ml, but increased only slowly or became saturated at higher prey concentrations. The maximum ingestion rate of O. marina on bacteria was much higher than those of G . cf. guttula and P. piscicida . Bacteria alone supported the growth of O. marina . The results of the present study suggest that some HTDs may sometimes have a considerable grazing impact on populations of marine bacteria, and that bacteria may be important prey.     

Recovery and diversity of heterotrophic bacteria from chlorinated drinking waters.

Heterotrophic bacteria were enumerated from the Seattle drinking water catchment basins and distribution system. The highest bacterial recoveries were obtained by using a very dilute medium containing 0.01% peptone as the primary carbon source. Other factors favoring high recovery were the use of incubation temperatures close to that of the habitat and an extended incubation (28 days or longer provided the highest counts). Total bacterial counts were determined by using acridine orange staining. With one exception, all acridine orange counts in chlorinated samples were lower than those in prechlorinated reservoir water, indicating that chlorination often reduces the number of acridine orange-detectable bacteria. Source waters had higher diversity index values than did samples examined following chlorination and storage in reservoirs. Shannon index values based upon colony morphology were in excess of 4.0 for prechlorinated source waters, whereas the values for final chlorinated tap waters were lower than 2.9. It is not known whether the reduction in diversity was due solely to chlorination or in part to other factors in the water treatment and distribution system. Based upon the results of this investigation, we provide a list of recommendations for changes in the procedures used for the enumeration of heterotrophic bacteria from drinking waters.     

Distribution and significance of heterotrophic marine bacteria with antibacterial activity.

Bacteria with antibacterial activity were isolated from seawater, sediments, phytoplankton, and zooplankton of Suruga, Sagami, and Tokyo Bays and from soft corals and sponges collected from the Taiwan coast. Of the 726 strains isolated, 37 showed antibacterial activity against either Vibrio parahaemolyticus (ATCC 17802) or Staphylococcus aureus (P209). Sediment harbored the lowest number of these forms of bacteria, and those from Tokyo Bay did not show any activity. Attached isolates showed greater activity compared with free-living forms. Relatively high numbers of strains with antibacterial activity were associated with phytoplankton. Among the zooplankton isolates, cladocerans harbored the maximum number of antibacterial strains. Isolates were more inhibitory to gram-positive test cultures. Autoinhibition was observed only among 8% of the isolates. Marine nonproducers were more susceptible. Pseudomonas/Alteromonas species made up 81.0% of isolates, of which 30% were pigmented strains. The absence or reduction in number of bacteria with antibacterial activity in Tokyo Bay is attributed to its eutrophic nature, which may tend to moderate the production of antibacterial compounds.     

Some factors affecting the heterotrophic activity of bacteria in lake.

The heterotrophic activity of aquatic bacteria was measured by incorporation of 3H-thymidine, uptake of 14C-sodium acetate and mineralization of 14C-acetate. The temperature of water, oxygen content and concentration of chlorophyll a were also measured in the studied lakes. The obtained results of the studied processes in the surface layer and epilimnion were distinguished by negative correlation coefficients. A distinctive feature is the relation between chlorophyll a concentration in the water bodies and heterotrophic activity of bacteria. This indicates a negative dependence between these processes and phytoplankton activity in the photic zone. In contrast a positive relationship between phytoplankton activity and heterotrophic activity of bacteria was found in the metalimnion and hypolimnion of the studied lakes.     

Soil heterotrophic bacteria in transformations of inorganic sulphur

The occurrence of biochemical activities of the sulphur cycle was followed in isolates of heterotrophic bacteria from the fermentative horizon of a spruce stand, a grass-covered withered spruce stand and of mountain ash and birch stand in the area strongly influenced by sulphur immissions. The occurrence of bacteria capable of reducing S⁰ to S²⁻, oxidizing S⁰ and S₂O₃ ²⁻ to SO₄ ²⁻ and solubilizing S⁰ increased in the above order. The occurrence of producers of thiosulphate sulphurtransferase (rhodanese), thiosulphate oxidase and sulphite oxidase increased and the level of the production of these enzymes increased as well. Heterotrophic bacteria (mostly pseudomonads) from the grass-covered stands exhibit more activities of the sulphur cycle than bacteria from the spruce stand without ground vegetation.     

Characterization of dysgonic, heterotrophic bacteria from drinking water.

Only a small percentage of the heterotrophic bacteria encountered in water distribution systems are identifiable, because of these organisms fail to grow on the conventional media used for biochemical characterization. Organisms that would not subculture from the same standard plate count agar used for initial isolation were successfully subcultured on a low-nutrient medium, R3A. These cultures were then inoculated to a modified O/F base medium containing specific substrates. This, combined with a lower incubation temperature (30 degrees C), increased the enzymatic activity of many of the organisms. These reactions established a groundwork for tentative taxonomy.