1
|
Zhang Q, He X, Yan T. Differential Decay of Wastewater Bacteria and Change of Microbial Communities in Beach Sand and Seawater Microcosms. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:8531-40. [PMID: 26125493 DOI: 10.1021/acs.est.5b01879] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Laboratory microcosm experiments were conducted to determine the decay kinetics of wastewater bacteria and the change of microbial communities in beach sand and seawater. Cultivation-based methods showed that common fecal indicator bacteria (FIBs; Escherichia coli, enterococci, and Clostridium perfringens) exhibited biphasic decay patterns in all microcosms. Enterococci and C. perfringens, but not E. coli, showed significantly smaller decay rates in beach sand than in seawater. Cultivation-independent qPCR quantification of 16S rRNA gene also showed significantly slower decrease of total bacterial densities in beach sand than in seawater. Microbial community analysis by next-generation sequencing (NGS) further illustrated that the decreasing relative abundance of wastewater bacteria was contrasted by the increase in indigenous beach sand and seawater microbiota, and the overall microbial community dynamics corresponded well with the decay of individual FIB populations. In summary, the differential decay of wastewater bacteria in beach sand and in seawater provides a kinetic explanation to the often-observed higher abundance of FIBs in beach sand, and the NGS-based microbial community analysis can provide valuable insights to understanding the fate of wastewater bacteria in the context of indigenous microbial communities in natural environments.
Collapse
Affiliation(s)
- Qian Zhang
- Department of Civil and Environmental Engineering, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Xia He
- Department of Civil and Environmental Engineering, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| | - Tao Yan
- Department of Civil and Environmental Engineering, University of Hawaii at Manoa, Honolulu, Hawaii 96822, United States
| |
Collapse
|
2
|
Malham SK, Rajko-Nenow P, Howlett E, Tuson KE, Perkins TL, Pallett DW, Wang H, Jago CF, Jones DL, McDonald JE. The interaction of human microbial pathogens, particulate material and nutrients in estuarine environments and their impacts on recreational and shellfish waters. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2014; 16:2145-2155. [PMID: 25043898 DOI: 10.1039/c4em00031e] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Anthropogenic activities have increased the load of faecal bacteria, pathogenic viruses and nutrients in rivers, estuaries and coastal areas through point and diffuse sources such as sewage discharges and agricultural runoff. These areas are used by humans for both commercial and recreational activities and are therefore protected by a range of European Directives. If water quality declines in these zones, significant economic losses can occur. Identifying the sources of pollution, however, is notoriously difficult due to the ephemeral nature of discharges, their diffuse source, and uncertainties associated with transport and transformation of the pollutants through the freshwater-marine interface. Further, significant interaction between nutrients, microorganisms and particulates can occur in the water column making prediction of the fate and potential infectivity of human pathogenic organisms difficult to ascertain. This interaction is most prevalent in estuarine environments due to the formation of flocs (suspended sediment) at the marine-freshwater interface. A range of physical, chemical and biological processes can induce the co-flocculation of microorganisms, organic matter and mineral particles resulting in pathogenic organisms becoming potentially protected from a range of biotic (e.g. predation) and abiotic stresses (e.g. UV, salinity). These flocs contain and retain macro- and micro- nutrients allowing the potential survival, growth and transfer of pathogenic organisms to commercially sensitive areas (e.g. beaches, shellfish harvesting waters). The flocs can either be transported directly to the coastal environment or can become deposited in the estuary forming cohesive sediments where pathogens can survive for long periods. Especially in response to storms, these sediments can be subsequently remobilised releasing pulses of potential pathogenic organisms back into the water column leading to contamination of marine waters long after the initial contamination event occurred. Further work, however, is still required to understand and predict the potential human infectivity of pathogenic organisms alongside the better design of early warning systems and surveillance measures for risk assessment purposes.
Collapse
Affiliation(s)
- Shelagh K Malham
- Centre for Applied Marine Science, Bangor University, Menai Bridge, Anglesey LL59 5AB, UK
| | | | | | | | | | | | | | | | | | | |
Collapse
|
3
|
Indigenous microbiota and habitat influence Escherichia coli survival more than sunlight in simulated aquatic environments. Appl Environ Microbiol 2013; 79:5329-37. [PMID: 23811514 DOI: 10.1128/aem.01362-13] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The reported fate of Escherichia coli in the environment ranges from extended persistence to rapid decline. Incomplete understanding of factors that influence survival hinders risk assessment and modeling of the fate of fecal indicator bacteria (FIB) and pathogens. FIB persistence in subtropical aquatic environments was explored in outdoor mesocosms inoculated with five E. coli strains. The manipulated environmental factors were (i) presence or absence of indigenous microbiota (attained by natural, disinfected, and cycloheximide treatments), (ii) freshwater versus seawater, and (iii) water column versus sediment matrices. When indigenous microbes were removed (disinfected), E. coli concentrations decreased little despite exposure to sunlight. Conversely, under conditions that included the indigenous microbiota (natural), significantly greater declines in E. coli occurred regardless of the habitat. The presence of indigenous microbiota and matrix significantly influenced E. coli decline, but their relative importance differed in freshwater versus seawater. Cycloheximide, which inhibits protein synthesis in eukaryotes, significantly diminished the magnitude of E. coli decline in water but not in sediments. The inactivation of protozoa and bacterial competitors (disinfected) caused a greater decline in E. coli than cycloheximide alone in water and sediments. These results indicate that the autochthonous microbiota are an important contributor to the decline of E. coli in fresh and seawater subtropical systems, but their relative contribution is habitat dependent. This work advances our understanding of how interactions with autochthonous microbiota influence the fate of E. coli in aquatic environments and provides the framework for studies of the ecology of enteric pathogens and other allochthonous bacteria in similar environments.
Collapse
|
4
|
Differential decay of enterococci and Escherichia coli originating from two fecal pollution sources. Appl Environ Microbiol 2013; 79:2488-92. [PMID: 23377944 DOI: 10.1128/aem.03781-12] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Using in situ subtropical aquatic mesocosms, fecal source (cattle manure versus sewage) was shown to be the most important contributor to differential loss in viability of fecal indicator bacteria (FIB), specifically enterococci in freshwater and Escherichia coli in marine habitats. In this study, sunlight exposure and indigenous aquatic microbiota were also important contributors, whose effects on FIB also differed between water types.
Collapse
|
5
|
Prasanna MV, Nagarajan R, Chidambaram S, Elayaraja A. Assessment of metals distribution and microbial contamination at selected lake waters in and around Miri City, East Malaysia. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2012; 89:507-511. [PMID: 22684361 DOI: 10.1007/s00128-012-0698-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Accepted: 06/01/2012] [Indexed: 06/01/2023]
Abstract
A baseline study was carried out to assess the metal concentrations and microbial contamination at selected Lake waters in and around Miri City, East Malaysia. Sixteen surface water samples were collected at specific Lakes in the environs of major settlement areas and recreational centers in Miri City. The Physico-chemical parameters [pH, Electrical Conductivity (EC) and Dissolved Oxygen (DO)], metals (Fe, Mn, Cu, Cd, Ni and Zn) and Escherichia coli (E. coli) were analysed. The concentrations of Fe, Mn and Ni have been found to be above the permissible limits of drinking water quality standards. The metals data have also been used for the calculation of heavy metal pollution index. Higher values of E. coli indicate microbial contamination in the Lake waters.
Collapse
Affiliation(s)
- M V Prasanna
- Department of Applied Geology, School of Engineering and Science, Curtin University, CDT 250, 98009, Miri, Sarawak, Malaysia.
| | | | | | | |
Collapse
|
6
|
Almeida C, Soares F. Microbiological monitoring of bivalves from the Ria Formosa Lagoon (south coast of Portugal): a 20 years of sanitary survey. MARINE POLLUTION BULLETIN 2012; 64:252-262. [PMID: 22197556 DOI: 10.1016/j.marpolbul.2011.11.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 11/24/2011] [Accepted: 11/30/2011] [Indexed: 05/31/2023]
Abstract
The microbiological pollution of coastal waters is a major problem, especially in shellfish areas. This article shows the faecal contamination in bivalves from the Ria Formosa Lagoon (south coast of Portugal) along 20 years (1990-2009). The highest values of Escherichia coli in bivalves were obtained during the 90s, related with the discharge of untreated wastewaters and agricultural runoff. In the 2000s contamination levels decreased, with 83% of the population already served by new or remodelled sewage treatment plants. The highest levels were found in bivalves close to the largest city, where punctual and diffuse contamination sources still exist. Bivalves from the less impacted site showed the lowest contamination, an area with more water renewal. Seasonally, the highest levels were in autumn and winter, due to the runoff of waters from rainfall. These were opposite to those in spring and summer, when the highest temperatures and salinity showed a bactericidal effect.
Collapse
Affiliation(s)
- Catarina Almeida
- INRB I.P./IPIMAR-Instituto de Investigação das Pescas e do Mar, Av. 5 de Outubro s/n, 8700-305 Olhão, Portugal
| | | |
Collapse
|
7
|
Futch JC, Griffin DW, Lipp EK. Human enteric viruses in groundwater indicate offshore transport of human sewage to coral reefs of the Upper Florida Keys. Environ Microbiol 2009; 12:964-74. [PMID: 20105219 DOI: 10.1111/j.1462-2920.2010.02141.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To address the issue of human sewage reaching corals along the main reef of the Florida Keys, samples were collected from surface water, groundwater and coral [surface mucopolysaccharide layers (SML)] along a 10 km transect near Key Largo, FL. Samples were collected semi-annually between July 2003 and September 2005 and processed for faecal indicator bacteria (faecal coliform bacteria, enterococci and Clostridium perfringens) and human-specific enteric viruses (enterovirus RNA and adenovirus DNA) by (RT)-nested polymerase chain reaction. Faecal indicator bacteria concentrations were generally higher nearshore and in the coral SML. Enteric viruses were evenly distributed across the transect stations. Adenoviruses were detected in 37 of 75 samples collected (49.3%) whereas enteroviruses were only found in 8 of 75 samples (10.7%). Both viruses were detected twice as frequently in coral compared with surface water or groundwater. Offshore, viruses were most likely to be found in groundwater, especially during the wet summer season. These data suggest that polluted groundwater may be moving to the outer reef environment in the Florida Keys.
Collapse
Affiliation(s)
- J Carrie Futch
- The University of Georgia, Department of Environmental Health Science, Athens, GA 30602, USA
| | | | | |
Collapse
|
8
|
Servais P, Garcia-Armisen T, George I, Billen G. Fecal bacteria in the rivers of the Seine drainage network (France): sources, fate and modelling. THE SCIENCE OF THE TOTAL ENVIRONMENT 2007; 375:152-67. [PMID: 17239424 DOI: 10.1016/j.scitotenv.2006.12.010] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The Seine river watershed (France) is a deeply anthropogenically impacted area, due to the high population density, intense industrial activities and intensive agriculture. The water quality and ecological functioning of the different rivers of the Seine drainage network have been extensively studied during the last fifteen years within the framework of a large French multidisciplinary scientific program (PIREN Seine program). This paper presents a synthesis of the main data gained in the scope of this program concerning the microbiological water contamination of the rivers of the Seine drainage network. The more common indicator of fecal contamination (fecal coliforms) was mainly used; some complementary works used E. coli and intestinal enterococci as alternative fecal indicators. Point sources (outfall of wastewater treatment plants) and non point sources (surface runoff and soil leaching) of fecal pollution to the rivers of the watershed were quantified. Results showed that, at the scale of a large urbanised watershed as the Seine basin, the input of fecal micro-organisms by non-point sources is much lower than the inputs by point sources. However, the local impact of diffuse non-human sources (especially surface runoff of pastured fields) can be of major importance on the microbiological quality of small headwater rivers. Fecal contamination of the main rivers of the Seine watershed (Seine, Marne, Oise rivers) was studied showing high level of microbiological pollution when compared to European guidelines for bathing waters. The strong negative impact of treated wastewater effluents outfall on the microbiological quality of receiving rivers was observed in different areas of the watershed. Once released in rivers, culturable fecal bacteria disappeared relatively rapidly due to mortality (protozoan grazing, lysis) or loss of culturability induced by stress conditions (sunlight effect, nutrient concentration, temperature). Mortality rates of E. coli were studied in different types of rivers within the watershed showing, in summer conditions, no major difference in the mortality rates in small and large rivers. As a result of these studies, a module describing the dynamics of fecal bacteria has been developed and embedded within a hydro-ecological model describing the functioning of the rivers of the whole watershed (the SENEQUE model). Once validated, such a model can be used for testing predictive scenarios and thus can be a very useful tool for the management of microbiological water quality at the scale of the whole basin.
Collapse
Affiliation(s)
- Pierre Servais
- Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Campus de la Plaine, CP 221, B-1050 Bruxelles, Belgique
| | | | | | | |
Collapse
|
9
|
Menon P, Billen G, Servais P. Mortality rates of autochthonous and fecal bacteria in natural aquatic ecosystems. WATER RESEARCH 2003; 37:4151-4158. [PMID: 12946897 DOI: 10.1016/s0043-1354(03)00349-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Bacterial mortality has been investigated in freshwater (River Seine) and in marine (North Sea) systems using a method based on following the disappearance of radioactivity from the DNA of assemblages of bacteria previously labeled with tritiated thymidine. Measurement of bacterial mortality of autochthonous and various types of fecal bacteria allowed direct comparisons between their respective first-order mortality rates. Mortality rates obtained for the different types of bacteria in the River Seine were, respectively, 7.9-33.9 x 10(-3)h(-1) for Escherichia coli, 12.2-29.2 x 10(-3)h(-1) for S. faecium and 7.0-18.3 x 10(-3)h(-1) for the autochthonous bacteria. In the Belgian coastal waters, these rates were 4.6-27.3 x 10(-3)h(-1) for E. coli, 6.0-22.0 x 10(-3)h(-1) for S. typhimurium, 10.0-18.9 x 10(-3)h(-1) for S. faecium and 1.0-13.9 x 10(-3)h(-1) for autochthonous bacteria. In both environments, the overall mortality rates of autochthonous and the different fecal bacteria were in the same order of magnitude and overall mortality rates of E. coli were on average about twice as high for autochthonous bacteria. Grazing by protozooplankton was the dominant process of mortality for fecal and autochthonous bacteria in both environments. Except in a few situations, grazing by protozooplankton was responsible for more than 90% of the overall mortality rate of fecal and autochthonous bacteria in the river and in the coastal area.
Collapse
Affiliation(s)
- Patricia Menon
- Ecologie des Systèmes Aquatiques, Université Libre de Bruxelles, Campus de la Plaine, CP 221 Boulevard du Triomphe, B1050 Bruxelles, Belgium
| | | | | |
Collapse
|
10
|
Darakas E. E. coli kinetics--effect of temperature on the maintenance and respectively the decay phase. ENVIRONMENTAL MONITORING AND ASSESSMENT 2002; 78:101-110. [PMID: 12229917 DOI: 10.1023/a:1016313520396] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The knowledge of enteric bacteria survival kinetic is very important for environmental scientists. Enteric bacteria and specifically the fecal indicator bacteria are typically used to measure the sanitary quality of water for recreational, industrial, agricultural and water supply purposes. They are released into the environment with feces, and are then exposed to a variety of environmental conditions that eventually cause their death. In general, it is believed that the fecal indicator cannot grow in natural environments, since they are adapted to live in the gastrointestinal tract. Studies have shown that fecal indicator bacteria survive from a few hours up to several days in surface water, but may survive for days or months in lake-sediments, where they may be protected from sunlight and predators. We assume that pathogens similar to the fecal indicator bacteria die at the same rate as fecal indicator bacteria. Therefore, if we find relatively high numbers of fecal indicator bacteria in an environment, we assume that there is an increased likelihood of pathogens being present as well. The kinetic of enteric bacteria survival in natural waters is affected by a large number of factors. One of them is the temperature. The aim of this contribution was the experimental research of the survival kinetic of enteric bacteria applying a simple mathematical formula, which describes the survival kinetic predicting the decay phase at various temperatures. We aspire that the results will lead both to the solution of many engineering problems and to future research.
Collapse
Affiliation(s)
- Efthymios Darakas
- Department of Civil Engineering, Aristotle University of Thessaloniki, Greece.
| |
Collapse
|
11
|
Darakas E. A simple mathematical formula describing the survival kinetics ofE.coliin natural waters. ACTA ACUST UNITED AC 2001. [DOI: 10.1080/00207230108711338] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
12
|
Griffin DW. Microbial public health indicators in the marine environment. J Microbiol Methods 2001. [DOI: 10.1016/s0580-9517(01)30062-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
|
13
|
GRIFFIN DALEW, LIPP ERINK, McLAUGHLIN MOLLYR, ROSE JOANB. Marine Recreation and Public Health Microbiology: Quest for the Ideal Indicator. Bioscience 2001. [DOI: 10.1641/0006-3568(2001)051[0817:mraphm]2.0.co;2] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
|
14
|
Petit M, George I, Servais P. Survival of Escherichia coli in freshwater: β-D-Glucuronidase activity measurements and characterization of cellular states. Can J Microbiol 2000. [DOI: 10.1139/w00-040] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A rapid enzyme assay measuring β-D-glucuronidase activity of Escherichia coli was tested in survival experiments after discharge of E. coli in river water. Enzyme activity was compared with several analyses performed to characterize cellular states under stressful conditions. Enzyme activity remained stable under starvation and light stress conditions despite losses of culturability, respiratory activity, and cytoplasmic membrane integrity. β-D-Glucuronidase activity followed the pattern of genetic and morphologic cell integrity. The tested enzyme assay seems well adapted to study the fate of fecal coliforms in survival experiments, and appears to be a rapid and efficient way to estimate the microbiological quality of surface waters.Key words: β-D-glucuronidase activity, Escherichia coli, survival, freshwater, cellular states.
Collapse
|
15
|
|
16
|
Martin Y, Troussellier M, Bonnefont JL. Adaptative responses of E. coli to marine environmental stresses: a modelling approach based on viability and dormancy concepts. ACTA ACUST UNITED AC 1998. [DOI: 10.1016/s0399-1784(99)80018-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
|
17
|
Menon P, Becquevort S, Billen G, Servais P. Kinetics of flagellate grazing in the presence of two types of bacterial prey. MICROBIAL ECOLOGY 1996; 31:89-101. [PMID: 24185639 DOI: 10.1007/bf00175078] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/1994] [Revised: 04/04/1995] [Indexed: 06/02/2023]
Abstract
Grazing rates of mixed cultures of freshwater, heterotrophic nanoflagellates on two populations of bacterial prey present together at varying concentrations were measured by using fluorescently labeled bacteria. The effect of one population on the ingestion kinetics of the other was consistent with a theory based on competitive inhibition of enzymatic reactions. However, allochthonous bacteria, when present in low concentrations within a much larger population of small autochthonous bacteria, may be preferentially grazed, which is due to their large size.
Collapse
Affiliation(s)
- P Menon
- Groupe de Microbiologie des Milieux Aquatiques, Université Libre de Bruxelles, Campus de la Plaine, CP 221, B-1050, Brussels, Belgium
| | | | | | | |
Collapse
|
18
|
Christoffersen K, Ahl T, Nybroe O. Grazing of nonindigenous bacteria by nano-sized protozoa in a natural coastal system. MICROBIAL ECOLOGY 1995; 30:67-78. [PMID: 24185413 DOI: 10.1007/bf00184514] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/1994] [Revised: 10/31/1994] [Indexed: 06/02/2023]
Abstract
Mesocosms (∼4.5 m(3)) situated in a closed bay area were used to investigate the effect of protozoan predation on nonindigenous bacteria. Pseudomonas fluorescens strain Agl was released into mesocosms as a single inoculum of 1 × 10(5) cells ml(-1) (final concentration) or as four inocula (same concentration each) at intervals of 3 days. Mesocosms that had received growth media corresponding to the inoculum served as controls. Numbers of P. fluorescens Ag1 decreased rapidly whether released as single or multiple inocula. Direct estimation of protozoan predation using fluorescently labeled P. fluorescens from log phase and starved cultures, respectively, revealed that natural populations of heterotrophic nanoflagellates consumed substantial amounts of the nonindigenous bacterial strain. The volume of fluorescently labeled cells prepared from starved cells was 68% of log phase cell volume, but the individual clearance of the small cells was five to seven times higher than that of the log phase bacteria. The natural populations of nanoflagellates consumed 34-62% of P. fluorescens Ag1 daily if starved bacteria were offered as food, and 3-13% if the cells were in the logarithmic growth phase. This suggests that the effect of protozoan predation on nonindigenous bacterial strains is substantial because cultured bacteria are likely to starve in natural environments. The addition of P. fluorescens Ag1 and the growth medium enhanced the abundance of natural bacteria, chlorophyll a, heterotrophic nanoflagellates, and ciliates, but it did not improve the growth conditions for the released strain. The effects on the indigenous populations were more pronounced after addition of fresh medium than following inoculation with cells, which possibly was due to the lower nutrient content of spent medium. However, these results, based on direct estimation of protozoan predation on log phase and starved nonindigenous bacteria, point to the conclusion that mortality induced by bacterivorous predators is the key factor determining removal of nonindigenous bacteria introduced in natural aquatic systems.
Collapse
Affiliation(s)
- K Christoffersen
- 'Freshwater Biological Laboratory, University of Copenhagen, Helsingørsgade 51, DK-3400, Hillerød, Denmark
| | | | | |
Collapse
|
19
|
Parekh NR, Walker A, Roberts SJ, Welch SJ. Rapid degradation of the triazinone herbicide metamitron by a Rhodococcus sp. isolated from treated soil. THE JOURNAL OF APPLIED BACTERIOLOGY 1994; 77:467-75. [PMID: 8002472 DOI: 10.1111/j.1365-2672.1994.tb04389.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Seven bacterial isolates which degraded the herbicide metamitron (3-methyl-4-amino-6-phenyl-1,2,4-triazin-5-one) were obtained from field-enhanced soil by liquid enrichment culture. All isolates appeared to be identical and a representative, 0246b, was identified as a Rhodococcus sp. by cell wall and fatty acid analyses. This isolate degraded metamitron as the sole source of carbon within 24 h at 25 degrees C and this is the first report of a bacterium capable of growing with metamitron as the sole source of carbon. Metamitron was degraded less rapidly when it was the sole source of both carbon and nitrogen. The rate and extent of degradation was affected by the presence and type of additional sources of carbon and nitrogen in the culture medium. In studies with [14C]-phenyl-labelled metamitron Rhodococcus sp. 0246b partly mineralized the phenyl ring.
Collapse
Affiliation(s)
- N R Parekh
- Horticulture Research International, Wellesbourne, Warwick, UK
| | | | | | | |
Collapse
|
20
|
González JM, Iriberri J, Egea L, Barcina I. Characterization of culturability, protistan grazing, and death of enteric bacteria in aquatic ecosystems. Appl Environ Microbiol 1992; 58:998-1004. [PMID: 1575503 PMCID: PMC195368 DOI: 10.1128/aem.58.3.998-1004.1992] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Nonstained bacteria (NSB), rhodamine-stained bacteria (RSB), and fluorescence-labeled bacteria (FLB) were prepared from two enteric bacterial species, Escherichia coli and Enterococcus faecalis. Counts of CFU of NSB and RSB and total numbers of RSB and FLB were monitored over time, both in the presence and in the absence of natural microbiota. In the presence of natural microbiota, no differences were observed between CFU counts of NSB and RSB, but RSB total numbers were 1 to 4 orders of magnitude higher than CFU numbers. Therefore, the use of standard bacteriological media causes an important underestimation of the total number of enteric bacteria. In the absence of natural microbiota, the total numbers of NSB, RSB, and FLB remained constant over time. These results showed that RSB are a reliable indicator of the decay in both the total number and the CFU of enteric bacteria in natural water samples. By using RSB, enteric bacteria were classified as culturable cells, nonculturable cells (or somnicells), and dead cells in the presence of natural microbiota. In the presence of natural microbiota, differences between RSB and FLB direct counts were detected for E. coli, but not for E. faecalis. These differences were explained by size-selective grazing. Thus, protistan grazing was found to be the main cause of the decrease in total numbers of enteric bacteria in our experiments.
Collapse
Affiliation(s)
- J M González
- Departamento de Microbiología e Immunología, Facultad de Ciencias, Universidad del País Vasco, Bilbao, Spain
| | | | | | | |
Collapse
|