Two approaches to modeling kinetics of biodegradation by growing cells and application of a two-compartment model for mineralization kinetics in sewage

The patterns of microbial mineralization of 0.3 to 30 ng of glucose, benzoate, and phenol per ml of sewage collected in late fall and winter were analyzed with the integrated Monod equation and a model in which growth of active organisms occurs at the expense of organic compounds other than the test substrate. Either model could be closely fit by nonlinear regression to the data from individual tests with one concentration of substrate added to one dilution of sewage. However, neither model accounted satisfactorily for differences in patterns of mineralization resulting from differences in substrate concentration and cell density between different tests. It is suggested that both the added substrates and other organics present in sewage contributed to the growth of the active organisms. The mineralization of glucose in sewage collected in summer was better described by a two-compartment model than by any other model tested.     

Two approaches to modeling kinetics of biodegradation by growing cells and application of a two-compartment model for mineralization kinetics in sewage.

The patterns of microbial mineralization of 0.3 to 30 ng of glucose, benzoate, and phenol per ml of sewage collected in late fall and winter were analyzed with the integrated Monod equation and a model in which growth of active organisms occurs at the expense of organic compounds other than the test substrate. Either model could be closely fit by nonlinear regression to the data from individual tests with one concentration of substrate added to one dilution of sewage. However, neither model accounted satisfactorily for differences in patterns of mineralization resulting from differences in substrate concentration and cell density between different tests. It is suggested that both the added substrates and other organics present in sewage contributed to the growth of the active organisms. The mineralization of glucose in sewage collected in summer was better described by a two-compartment model than by any other model tested.     

Comparison of Sewage and Animal Fecal Microbiomes by Using Oligotyping Reveals Potential Human Fecal Indicators in Multiple Taxonomic Groups

Most DNA-based microbial source tracking (MST) approaches target host-associated organisms within the order Bacteroidales, but the gut microbiota of humans and other animals contain organisms from an array of other taxonomic groups that might provide indicators of fecal pollution sources. To discern between human and nonhuman fecal sources, we compared the V6 regions of the 16S rRNA genes detected in fecal samples from six animal hosts to those found in sewage (as a proxy for humans). We focused on 10 abundant genera and used oligotyping, which can detect subtle differences between rRNA gene sequences from ecologically distinct organisms. Our analysis showed clear patterns of differential oligotype distributions between sewage and animal samples. Over 100 oligotypes of human origin occurred preferentially in sewage samples, and 99 human oligotypes were sewage specific. Sequences represented by the sewage-specific oligotypes can be used individually for development of PCR-based assays or together with the oligotypes preferentially associated with sewage to implement a signature-based approach. Analysis of sewage from Spain and Brazil showed that the sewage-specific oligotypes identified in U.S. sewage have the potential to be used as global alternative indicators of human fecal pollution. Environmental samples with evidence of prior human fecal contamination had consistent ratios of sewage signature oligotypes that corresponded to the trends observed for sewage. Our methodology represents a promising approach to identifying new bacterial taxa for MST applications and further highlights the potential of the family Lachnospiraceae to provide human-specific markers. In addition to source tracking applications, the patterns of the fine-scale population structure within fecal taxa suggest a fundamental relationship between bacteria and their hosts.     

Assessment of bifidobacteria as indicators of human fecal pollution.

The distribution of bifidobacteria in the environment has been examined by using YN-6 medium. Although feces of humans, chickens, cows, dogs, pigs, horses, cats, sheep, beavers, goats, and turkeys were examined, bifidobacteria were isolated only from the feces of humans and swine. The frequency and distribution of component species of human fecal isolates were as in isolates from raw sewage. Bifidobacterium longum and B. adolescentis were most often isolated and in the highest densities. The levels of bifidobacteria in raw sewage were in the range of 10(6) organisms/100 ml, and the effect of primary and secondary sewage treatment on the number of viable organisms present was not significant. High densities of bifidobacteria were found in all samples from septic tanks. It was found that bifidobacteria did not survive as well as Escherichia coli in either fresh or marine waters. The ratio of bifidobacteria to E. coli is an indication of the age and of the effectiveness of treatment of sewage effluent.     

Enumeration of potentially pathogenic bacteria from sewage sludges.

To ascertain the health risks that may be posed by the land application of sewage sludges, a scheme was devised to determine the types and numbers of pathogenic and potentially pathogenic bacteria present in sludges. A processing treatment was adapted to sludge to give a homogenate which yielded the greatest numbers of viable bacteria. Conventional methods were successful in enumerating Klebsiella, Staphylococcus, gram-negative enteric bacteria, and commonly used indicator organisms. Modifications of conventional methods improved the enumeration of Salmonella, Mycobacterium sp., fluorescent Pseudomonas sp., and Clostridium perfringens. However, Shigella methodology yielded only one isolate. Utilizing the proposed scheme, the population densities of these organisms were estimated in three domestic wastewater sludges. In light of these results, the potential impact of land application of sewage sludges is discussed.     

Bacteriophage resistance of attached organisms as a factor in the survival of plasmid-bearing strains of Escherichia coli

Unattached organisms of plasmid-free and plasmid-bearing strains of Escherichia coli showed marked sensitivity to phages T4, Tula and K3 on incubation in broth at 37°C but organisms attached to glass beads or sand were resistant. Phage T4 sensitivity of free organisms and resistance of glass bead-attached ones were also observed when incubation was in broth at 15° or 20°C or anaerobically at 37°C. In contrast, free and attached organisms were resistant at 37°C or lower temperature when incubation was in poor media. It seems likely that the presence of phage will be a major factor reducing survival in the intestine and in sewage and that attachment (which is more significant for strains bearing certain plasmids) will protect. In contrast, survival of either free or attached organisms in polluted water will probably not be significantly influenced by the presence of phage.     

Enumeration of potentially pathogenic bacteria from sewage sludges

To ascertain the health risks that may be posed by the land application of sewage sludges, a scheme was devised to determine the types and numbers of pathogenic and potentially pathogenic bacteria present in sludges. A processing treatment was adapted to sludge to give a homogenate which yielded the greatest numbers of viable bacteria. Conventional methods were successful in enumerating Klebsiella, Staphylococcus, gram-negative enteric bacteria, and commonly used indicator organisms. Modifications of conventional methods improved the enumeration of Salmonella, Mycobacterium sp., fluorescent Pseudomonas sp., and Clostridium perfringens. However, Shigella methodology yielded only one isolate. Utilizing the proposed scheme, the population densities of these organisms were estimated in three domestic wastewater sludges. In light of these results, the potential impact of land application of sewage sludges is discussed.     

Storage effects of sewage sludge cake on the survival of Listeria monocytogenes

Sewage sludge cake is widely used as an agricultural fertilizer in Iraq. Listeria monocytogenes was shown to be present in small numbers in this material despite sewage treatments. In an attempt to reduce the numbers of this pathogen in this sewage end product, the survival of L. monocytogenes was monitored in a heap of sewage sludge cake stored for over 23 weeks on farm land. The organisms were reduced in numbers and eliminated to undetectable limits during 8 weeks of storage under subtropical weathering and did not recover even 2 months after disappearance. Dewatering processes seem to have some affect on the survival of the bacteria. Therefore, solar dewatering by heaping the sewage sludge cake and exposing it to sun for no less than 8 weeks is recommended to obtain a listeria-free product.     

Storage effects of sewage sludge cake on the survival of Listeria monocytogenes

Sewage sludge cake is widely used as an agricultural fertilizer in Iraq. Listeria monocytogenes was shown to be present in small numbers in this material despite sewage treatments. In an attempt to reduce the numbers of this pathogen in this sewage end product, the survival of L. monocytogenes was monitored in a heap of sewage sludge cake stored for over 23 weeks on farm land. The organisms were reduced in numbers and eliminated to undetectable limits during 8 weeks of storage under subtropical weathering and did not recover even 2 months after disappearence. Dewatering processes seem to have some affect on the survival of the bacteria. Therefore, solar dewatering by heaping the sewage sludge cake and exposing it to sun for no less than 8 weeks is recommended to obtain a listeria-free product.     

A note on salmonella excretion in the black headed gull (Larus ribibundus) feeding at sewage treatment works

The range of salmonella serotypes found in sewage sludge and in the faeces of black headed gulls (Larus ribibundus) feeding on the sludge was investigated. A close association was demonstrated between the serotypes found in both types of sample. Salmonella takoradi (a serotype which is uncommon in Scotland) appeared in the sludge for two short periods during the twelve week study and on both occasions it was later found in the gull faeces. It was shown that gulls become infected after feeding on contaminated sewage sludge but that the infection is probably short-lived.     

Microbial metabolism of quinoline and related compounds. IV. Degradation of isoquinoline by Alcaligenes faecalis Pa and Pseudomonas diminuta 7

From sewage and soil isoquinoline-degrading organisms were enriched. Two strains could be isolated which were able to utilize isoquinoline as sole carbon source. The bacteria were tentatively identified as Alcaligenes faecalis and Pseudomonas diminuta with respect to their morphological and physiological characters. When growing on isoquinoline both strains excrete a metabolite into the medium which was identified as 1-oxo-1,2-dihydroisoquinoline. Alcaligenes faecalis was cultivated in continuous culture on 1-oxo-1,2-dihydroisoquinoline to improve growth on isoquinoline and degradative activity.     

THE CONSTRUCTION OF BIOLOGICAL FILM IN A PERCOLATING SEWAGE FILTER

SUMMARY: On a microscope slide arranged to simulate a percolating sewage filter the sequence of invading organisms was examined and a primary and secondary invader recognised. These organisms form a substratum suitable for fungal growth.     

Detection of low numbers of pathogenic Yersinia enterocolitica in environmental water and sewage samples by nested polymerase chain reaction

Isolation of pathogenic Yersinia enterocolitica from water and sewage by traditional culture techniques is time-consuming and subsequent differentiation between pathogenic and non-pathogenic strains can be difficult and unreliable. A nested polymerase chain reaction (PCR) procedure was used for the detection of low numbers of Y. enterocolitica in spiked samples from natural surface sources with variable background flora ranging from oligotrophic water to sewage. Water and sewage samples were filtered and filters enriched overnight in a non-selective medium. Nested PCR conducted on enriched broth, prepared by use of a rapid and simple preparation step consisting of centrifugation, proteinase K treatment and boiling, enabled the detection of 8-17 cfu 100 ml-1 water with background levels of up to 8700 heterotrophic organisms ml-1 and 10,000 cfu coliform organisms 100 ml-1 water. The analysis can be completed within 2-3 d and should be a significant tool in monitoring environmental waters and drinking water sources for the presence of pathogenic Y. enterocolitica.     

A note on salmonella excretion in the black headed gull (Lams ribibundus) feeding at sewage treatment works

F ricker , C. R. 1984 A note on salmonella excretion in the black headed gull ( Larus ribibundus ) feeding at sewage treatment works. Journal of Applied Bacteriology 56 , 499–502.
The range of salmonella serotypes found in sewage sludge and in the faeces of black headed gulls ( Larus ribibundus ) feeding on the sludge was investigated. A close association was demonstrated between the serotypes found in both types of sample. Salmonella takoradi (a serotype which is uncommon in Scotland) appeared in the sludge for two short periods during the twelve week study and on both occasions it was later found in the gull faeces. It was shown that gulls become infected after feeding on contaminated sewage sludge but that the infection is probably shortlived.     

Evaluation of PCR, nested PCR, and fluorescent antibodies for detection of Giardia and Cryptosporidium species in wastewater.

Giardiasis and cryptosporidiosis are diseases caused by the protozoan parasites Giardia lamblia and Cryptosporidium parvum. Waterborne transmission of these organisms has become more prevalent in recent years, and regulatory agencies are urging that source and finished water be screened for these organisms. A major problem associated with testing for these organisms is the lack of reliable methodologies and baseline information on the prevalence of these parasites in various water sources. Our study addressed both of these issues. We evaluated the presence and reduction of Giardia cysts and Cryptosporidium oocysts in sewage effluent by a combination of indirect fluorescent antibody (IFA) staining and PCR. Our results indicated a 3-log reduction of Giardia cysts and a 2-log reduction of Cryptosporidium oocysts through the sewage treatment process as determined by IFA. We developed a nested PCR to detect Cryptosporidium oocysts and used a double PCR to detect Giardia cysts. A 100% correlation was noted between IFA and PCR detection of Giardia cysts while correlation for Cryptosporidium oocysts was slightly less. On the basis of these results, PCR may be a useful tool in the environmental analysis of water samples for Giardia and Cryptosporidium organisms.     

Role of resistance to starvation in bacterial survival in sewage and lake water

A study was conducted to determine the significance of starvation resistance to the ability of a species to survive in sewage and lake water. Tests were conducted for periods of up to 14 days. Rhizobium meliloti and one fluorescent and one nonfluorescent strain of Pseudomonas were resistant to starvation because their population sizes did not fall appreciably in buffer and sterile lake water, and the first two maintained high numbers after being added to sterile sewage. Cell densities of these bacterial species dropped slowly in nonsterile sewage, and more cells of these three organisms than of the other test organisms remained in nonsterile lake water. Rhizobium leguminosarum was moderately resistant to starvation because its numbers fell slowly in buffer and sterile lake water and did not change appreciably in sterile sewage. The abundance of Micrococcus flavus added to buffer and sterile lake water did not change, but the density of M. flavus declined in nonsterile lake water. The abundance of R. leguminosarum fell in nonsterile lake water and nonsterile sewage. Streptococcus faecalis, Staphylococcus aureus, an asporogenous strain of Bacillus subtilis, and Streptococcus sp. were susceptible to starvation because their populations were markedly reduced in buffer. Populations of the last three species declined rapidly in nonsterile and sterile samples of lake water and sewage. S. faecalis declined rapidly when added to nonsterile lake water and sewage and sterile lake water but not when added to sterile sewage, the persistence in the last instance probably being associated with the availability of organic nutrients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of resistance to starvation in bacterial survival in sewage and lake water.

A study was conducted to determine the significance of starvation resistance to the ability of a species to survive in sewage and lake water. Tests were conducted for periods of up to 14 days. Rhizobium meliloti and one fluorescent and one nonfluorescent strain of Pseudomonas were resistant to starvation because their population sizes did not fall appreciably in buffer and sterile lake water, and the first two maintained high numbers after being added to sterile sewage. Cell densities of these bacterial species dropped slowly in nonsterile sewage, and more cells of these three organisms than of the other test organisms remained in nonsterile lake water. Rhizobium leguminosarum was moderately resistant to starvation because its numbers fell slowly in buffer and sterile lake water and did not change appreciably in sterile sewage. The abundance of Micrococcus flavus added to buffer and sterile lake water did not change, but the density of M. flavus declined in nonsterile lake water. The abundance of R. leguminosarum fell in nonsterile lake water and nonsterile sewage. Streptococcus faecalis, Staphylococcus aureus, an asporogenous strain of Bacillus subtilis, and Streptococcus sp. were susceptible to starvation because their populations were markedly reduced in buffer. Populations of the last three species declined rapidly in nonsterile and sterile samples of lake water and sewage. S. faecalis declined rapidly when added to nonsterile lake water and sewage and sterile lake water but not when added to sterile sewage, the persistence in the last instance probably being associated with the availability of organic nutrients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of sewage treatment on the removal of Listeria monocytogenes

Two sewage treatment plants in Baghdad, Iraq, were investigated to assess the effects of the different treatment stages on the removal of Listeria monocytogenes. The bacteria were severely affected after the activation and digestion stages at both plants. A dramatic decrease in numbers of listerias after each of these two stages was noticed during the cold months (September-January). The organisms were able to survive these treatments and were present in the final effluent and even in low numbers in the sewage sludge cake. Sufficient dewatering of sewage sludge is recommended to obtain sewage free of listerias. Improvements in the isolation procedure of L. monocytogenes from such heavily contaminated material is also discussed.     

Effects of sewage treatment on the removal of Listeria monocytogenes

Two sewage treatment plants in Baghdad, Iraq, were investigated to assess the effects of the different treatment stages on the removal of Listeria monocytogenes . The bacteria were severely affected after the activation and digestion stages at both plants. A dramatic decrease in numbers of listerias after each of these two stages was noticed during the cold months (September-January). The organisms were able to survive these treatments and were present in the final effluent and even in low numbers in the sewage sludge cake. Sufficient dewatering of sewage sludge is recommended to obtain sewage free of listerias. Improvements in the isolation procedure of L. monocytogenes from such heavily contaminated material is also discussed.     

Explanations for the acclimation period preceding the mineralization of organic chemicals in aquatic environments

A study was conducted of possible reasons for acclimation of microbial communities to the mineralization of organic compounds in lake water and sewage. The acclimation period for the mineralization of 2 ng of p-nitrophenol (PNP) or 2,4-dichlorophenoxyacetic acid per ml of sewage was eliminated when the sewage was incubated for 9 or 16 days, respectively, with no added substrate. The acclimation period for the mineralization of 2 ng but not 200 ng or 2 micrograms of PNP per ml was eliminated when the compound was added to lake water that had been first incubated in the laboratory. Mineralization of PNP by Flavobacterium sp. was detected within 7 h at concentrations of 20 ng/ml to 2 micrograms/ml but only after 25 h at 2 ng/ml. PNP-utilizing organisms began to multiply logarithmically after 1 day in lake water amended with 2 micrograms of PNP per ml, but substrate disappearance was only detected at 8 days, at which time the numbers were approaching 10(5) cells per ml. The addition of inorganic nutrients reduced the length of the acclimation period from 6 to 3 days in sewage and from 6 days to 1 day in lake water. The prior degradation of natural organic materials in the sewage and lake water had no effect on the acclimation period for the mineralization of PNP, and naturally occurring inhibitors that might delay the mineralization were not present. The length of the acclimation phase for the mineralization of 2 ng of PNP per ml was shortened when the protozoa in sewage were suppressed by eucaryotic inhibitors, but it was unaffected or increased if the inhibitors were added to lake water.(ABSTRACT TRUNCATED AT 250 WORDS)