Biotransformation of polychlorinated biphenyls in St. Lawrence River sediments: reductive dechlorination and dechlorinating microbial populations

2000 ◽  
Vol 57 (S1) ◽  
pp. 95-100 ◽  
Author(s):  
Y -C Cho ◽  
J Kim ◽  
R C Sokol ◽  
G -Y Rhee
Keyword(s):  
Reductive Dechlorination ◽  
Polychlorinated Biphenyl ◽  
River Sediments ◽  
Dry Weight ◽  
Microbial Populations ◽  
Most Probable Number ◽  
Probable Number ◽  
Aroclor 1248 ◽  
Two Populations ◽  
St Lawrence River

Polychlorinated biphenyl dechlorinating microbial populations in St. Lawrence River sediments were fractionated and estimated based on the dechlorination pattern using a combination of serial dilution and most probable number techniques. Two distinctive dechlorination patterns were found in most probable number sediments spiked with Aroclor 1248. A high-dilution inoculum decreased the average number of chlorines per biphenyl from 4.0 to 3.4 but was unable to dechlorinate meta-substituted congeners consisting mainly of 2,5,2',5'-, 2,4,2',5'-, and 2,5,2'-chlorobiphenyl (pattern B). On the other hand, a low-dilution inoculum did dechlorinate the meta-rich congeners and reduced the average number of chlorines to 2.9 (pattern A). These results indicate that there are at least two populations. While pattern B was produced by pattern B producing dechlorinators, pattern A was produced by a combination of pattern B producers plus another population that dechlorinates the meta-substituted congeners. When the population size was calculated based on the frequency of respective dechlorination patterns, the populations yielding pattern B were approximately 2.4 × 106cells·g dry weight sediment-1whereas the dechlorinators of the meta-rich congeners were two orders of magnitude less at 3.5 × 104cells·g dry weight sediment-1. Despite lower numbers, these meta-dechlorinators in pattern A increased the overall dechlorination by almost twofold.

scholarly journals Sequential Reductive Dechlorination of meta-Chlorinated Polychlorinated Biphenyl Congeners in Sediment Microcosms by Two Different Chloroflexi Phylotypes

2005 ◽  
Vol 71 (12) ◽  
pp. 8085-8090 ◽  
Author(s):  
Sonja K. Fagervold ◽  
Joy E. M. Watts ◽  
Harold D. May ◽  
Kevin R. Sowers
Keyword(s):  
16S Rrna ◽  
Reductive Dechlorination ◽  
Polychlorinated Biphenyl ◽  
Denaturing Gradient Gel Electrophoresis ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Most Probable Number ◽  
Individual Species ◽  
Rrna Gene ◽  
Probable Number

ABSTRACT Three species within a deeply branching cluster of the Chloroflexi are the only microorganisms currently known to anaerobically transform polychlorinated biphenyls (PCBs) by the mechanism of reductive dechlorination. A selective PCR primer set was designed that amplifies the 16S rRNA genes of a monophyletic group within the Chloroflexi including Dehalococcoides spp. and the o-17/DF-1 group. Assays for both qualitative and quantitative analyses by denaturing gradient gel electrophoresis and most probable number-PCR, respectively, were developed to assess sediment microcosm enrichments that reductively dechlorinated PCBs 101 (2,2′,4,5,5′-CB) and 132 (2,2′,3,3′,4,6′-CB). PCB 101 was reductively dechlorinated at the para-flanked meta position to PCB 49 (2,2′,4,5′-CB) by phylotype DEH10, which belongs to the Dehalococcoides group. This same species reductively dechlorinated the para- and ortho-flanked meta-chlorine of PCB 132 to PCB 91 (2,2′,3′,4,6′-CB). However, another phylotype designated SF1, which is more closely related to the o-17/DF-1 group, was responsible for the subsequent dechlorination of PCB 91 to PCB 51 (2,2′,4,6′-CB). Using the selective primer set, an increase in 16S rRNA gene copies was observed only with actively dechlorinating cultures, indicating that PCB-dechlorinating activities by both phylotype DEH10 and SF1 were linked to growth. The results suggest that individual species within the Chloroflexi exhibit a limited range of congener specificities and that a relatively diverse community of species within a deeply branching group of Chloroflexi with complementary congener specificities is likely required for the reductive dechlorination of different PCBs congeners in the environment.

Reduction of Microorganisms on Citrus Fruit Surfaces during Packinghouse Processing

1998 ◽  
Vol 61 (7) ◽  
pp. 903-906 ◽  
Author(s):  
STEVEN PAO ◽  
G. ELDON BROWN
Keyword(s):  
Test Organism ◽  
Citrus Fruit ◽  
Microbial Populations ◽  
Most Probable Number ◽  
Probable Number ◽  
E Coli ◽  
Plate Counts ◽  
High Level ◽  
Inoculation Study ◽  
Fruit Surface

Citrus fruit surface microbial populations were evaluated following various packingline processes of seven Florida commercial packinghouses. At each packinghouse, six fruits (oranges or tangerines) were collected at each of four sampling points. The sampling was conducted in duplicate; thus, 336 fruit were evaluated during this survey. Average aerobic plate counts and yeast and mold counts on fruit surfaces before washing were about 4.0 log CFU/cm2 and 3.3 log CFU/cm2, respectively, and were reduced to 2.1 log CFU/cm2 and 1.3 log CFU/cm2, respectively, by packinghouse processing. Waxing alone reduced the average fruit surface aerobic plate counts and coliform counts from 3.7 log CFU/cm2 and 35.2 most probable number (MPN)/cm2, respectively, to 2.6 log CFU/cm2 and 1.4 MPN/cm2. No Escherichia coli was recovered from fruit at the end of packinghouse processing, and no salmonellae were found on fruit during the entire processing. In an inoculation study to test the effect of packinghouse processes, test organism E. coli was applied to fruit to achieve a high level (4.8 log CFU/cm2) of contamination. The average E. coli count was reduced about 2.4 log cycles by washing and rinsing with potable water (40 psi, 25 °C) for about 30 s. The combination of washing and waxing significantly reduced the inoculated level of E. coli from 4.8 to 1.4 log CFU/cm2.

scholarly journals Evidence for Microbial Fe(III) Reduction in Anoxic, Mining-Impacted Lake Sediments (Lake Coeur d'Alene, Idaho)

2000 ◽  
Vol 66 (1) ◽  
pp. 154-162 ◽  
Author(s):  
David E. Cummings ◽  
Anthony W. March ◽  
Benjamin Bostick ◽  
Stefan Spring ◽  
Frank Caccavo ◽  
...  
Keyword(s):  
Iron Reduction ◽  
Dry Weight ◽  
Most Probable Number ◽  
Probable Number ◽  
Coeur D'alene ◽  
Reduction Of Iron ◽  
Study Support ◽  
Reducing Bacteria ◽  
Microbiological Data

ABSTRACT Mining-impacted sediments of Lake Coeur d'Alene, Idaho, contain more than 10% metals on a dry weight basis, approximately 80% of which is iron. Since iron (hydr)oxides adsorb toxic, ore-associated elements, such as arsenic, iron (hydr)oxide reduction may in part control the mobility and bioavailability of these elements. Geochemical and microbiological data were collected to examine the ecological role of dissimilatory Fe(III)-reducing bacteria in this habitat. The concentration of mild-acid-extractable Fe(II) increased with sediment depth up to 50 g kg−1, suggesting that iron reduction has occurred recently. The maximum concentrations of dissolved Fe(II) in interstitial water (41 mg liter−1) occurred 10 to 15 cm beneath the sediment-water interface, suggesting that sulfidogenesis may not be the predominant terminal electron-accepting process in this environment and that dissolved Fe(II) arises from biological reductive dissolution of iron (hydr)oxides. The concentration of sedimentary magnetite (Fe3O4), a common product of bacterial Fe(III) hydroxide reduction, was as much as 15.5 g kg−1. Most-probable-number enrichment cultures revealed that the mean density of Fe(III)-reducing bacteria was 8.3 × 105 cells g (dry weight) of sediment−1. Two new strains of dissimilatory Fe(III)-reducing bacteria were isolated from surface sediments. Collectively, the results of this study support the hypothesis that dissimilatory reduction of iron has been and continues to be an important biogeochemical process in the environment examined.

Monitoring the Microbial Populations and Temperatures of Fresh Broccoli from Harvest to Retail Display†

2006 ◽  
Vol 69 (5) ◽  
pp. 1118-1125 ◽  
Author(s):  
R. DALLAIRE ◽  
D. I. LeBLANC ◽  
C. C. TRANCHANT ◽  
L. VASSEUR ◽  
P. DELAQUIS ◽  
...  
Keyword(s):  
Distribution System ◽  
Limit Of Detection ◽  
Fecal Coliforms ◽  
Microbial Populations ◽  
Most Probable Number ◽  
Probable Number ◽  
E Coli ◽  
Production And Distribution ◽  
Experimental Variability ◽  
Retail Display

Microbial populations and the temperature of fresh broccoli were monitored at several steps of a supply chain by sampling 33 distinct lots of locally grown produce over two seasons during harvest, storage, wholesale handling, and retail display. Imported broccoli was also sampled, but only at retail display. Microbiological analyses were conducted on the florets of 201 local and 60 imported broccoli samples to determine populations of total aerobic bacteria (aerobic colony count), fecal coliforms, Escherichia coli, and Listeria monocytogenes. All the samples had mean aerobic colony counts ranging between 4 and 6 log CFU/g, but L. monocytogenes was not detected (limit of detection = 100 CFU/g). Fecal coliforms and E. coli (limit of detection = 20 most probable number per 100 g) were found in 22 of 126 samples of local broccoli collected at various steps of the production and distribution system during the first season. None was found in 75 samples collected in the second season. Fecal coliforms and E. coli were found in 2 of 60 imported broccoli samples. Broccoli temperatures were relatively well controlled throughout the production and distribution system. No clear change in produce microbial populations was evident between harvest and retail display, during both sampling seasons. However, a large experimental variability was found, possibly associated with the high variability of the initial levels of microbial populations on broccoli at harvest.

Characterization and Identification of Numerically Abundant Culturable Bacteria from the Anoxic Bulk Soil of Rice Paddy Microcosms

1999 ◽  
Vol 65 (11) ◽  
pp. 5042-5049 ◽  
Author(s):  
Kuk-Jeong Chin ◽  
Dittmar Hahn ◽  
Ulf Hengstmann ◽  
Werner Liesack ◽  
Peter H. Janssen
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Dry Weight ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Most Probable Number ◽  
Rrna Gene ◽  
16S Rrna Gene Sequences ◽  
Probable Number ◽  
Clostridial Cluster

ABSTRACT Most-probable-number (liquid serial dilution culture) counts were obtained for polysaccharolytic and saccharolytic fermenting bacteria in the anoxic bulk soil of flooded microcosms containing rice plants. The highest viable counts (up to 2.5 × 108 cells per g [dry weight] of soil) were obtained by using xylan, pectin, or a mixture of seven mono- and disaccharides as the growth substrate. The total cell count for the soil, as determined by using 4′,6-diamidino-2-phenylindole staining, was 4.8 × 108cells per g (dry weight) of soil. The nine strains isolated from the terminal positive tubes in counting experiments which yielded culturable populations that were equivalent to about 5% or more of the total microscopic count population belonged to the divisionVerrucomicrobia, theCytophaga-Flavobacterium-Bacteroides division, clostridial cluster XIVa, clostridial cluster IX, Bacillus spp., and the class Actinobacteria. Isolates originating from the terminal positive tubes of liquid dilution series can be expected to be representatives of species whose populations in the soil are large. None of the isolates had 16S rRNA gene sequences identical to 16S rRNA gene sequences of previously described species for which data are available. Eight of the nine strains isolated fermented sugars to acetate and propionate (and some also fermented sugars to succinate). The closest relatives of these strains (except for the two strains of actinobacteria) were as-yet-uncultivated bacteria detected in the same soil sample by cloning PCR-amplified 16S rRNA genes (U. Hengstmann, K.-J. Chin, P. H. Janssen, and W. Liesack, Appl. Environ. Microbiol. 65:5050–5058, 1999). Twelve other isolates, which originated from most-probable-number counting series indicating that the culturable populations were smaller, were less closely related to cloned 16S rRNA genes.

Bacterial Populations of Ground Beef, Textured Soy Protein and Ground Beef Extended With Soy Protein After 3 and 10 Days of Refrigerated Storage1,2

1978 ◽  
Vol 41 (8) ◽  
pp. 647-653 ◽  
Author(s):  
JAMES F. FOSTER ◽  
RICHARD C. HUNDERFUND ◽  
JAMES L. FOWLER ◽  
JOHN T. FRUIN ◽  
LINDA S. GUTHERTZ
Keyword(s):  
Soy Protein ◽  
Ground Beef ◽  
Microbial Populations ◽  
Plate Count ◽  
Most Probable Number ◽  
Bacterial Populations ◽  
Probable Number ◽  
Fecal Streptococcus ◽  
Large Numbers ◽  
Aerobic Plate Count

A survey of the microbial populations of 31 samples of ground beef (GB), textured soy protein (TSP), and ground beef extended with TSP (SGB) after 3 and 10 days of storage at 4 C was done. Analyses included aerobic plate count (APC), psychrotrophic plate count (PPC), coliform Most Probable Number (CMPN) and plate determinations (CPC), Escherichia coli MPN (EMPN) and plate determinations (EPC), Staphylococcus aureus MPN, and fecal streptococcus plate count. Statistical analyses of data from the enumeration procedures showed significant increases in the total microbial flora after 10 days of storage. PPCs were significantly higher than APCs. CMPNs were significantly higher than CPCs for GB and SGB. The EMPNs were significantly higher than EPCs in SGB only. These products contained a variety of microorganisms many in large numbers; however if properly handled and cooked before consumption, these products should present no public health problems.

Defining the sources of airborne polychlorinated biphenyls: evidence for the influence of microbially dechlorinated congeners from river sediment?

2000 ◽  
Vol 57 (S1) ◽  
pp. 86-94 ◽  
Author(s):  
Jeff Chiarenzelli ◽  
Brian Bush ◽  
Ann Casey ◽  
Ed Barnard ◽  
Bob Smith ◽  
...  
Keyword(s):  
Great Lakes ◽  
River Sediment ◽  
Polychlorinated Biphenyl ◽  
Specific Pattern ◽  
Great Lakes Region ◽  
Superfund Sites ◽  
Aroclor 1248 ◽  
Time Period ◽  
A Minor ◽  
St Lawrence River

Sampling on Akwesasne Mohawk Nation lands during 1993 yielded elevated polychlorinated biphenyl (PCB) concentrations comparable with those of other areas impacted by the discharge of PCBs. The summer air PCB congener- specific pattern in proximity to three Superfund sites along the St. Lawrence River suggests that the volatilization of Aroclor 1248, used extensively at all three downwind sites, is the dominant source. A dechlorinated source, presumably from river sediment and waters, is a minor contributor (~12%) to the pattern. These two sources can account for ~80% of the observed pattern. At a small cove adjacent to an industrial landfill, summer concentrations exceeded those measured in the winter by a factor of 27. At all sample sites during the summer months (June-August), concentrations and chlorine to biphenyl ratios increased, and similar congener-specific PCB patterns were observed. During the colder months, PCB concentrations at all sites decreased but were elevated with respect to those measured elsewhere in the Great Lakes region during the same time period.

In‐situ apparent conductivity measurements and microbial population distribution at a hydrocarbon‐contaminated site

Geophysics ◽  
2004 ◽  
Vol 69 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Estella A. Atekwana ◽  
D. Dale Werkema ◽  
Joseph W. Duris ◽  
Silvia Rossbach ◽  
Eliot A. Atekwana ◽  
...  
Keyword(s):  
Microbial Degradation ◽  
Microbial Population ◽  
Population Distribution ◽  
Microbial Populations ◽  
Contaminated Site ◽  
Most Probable Number ◽  
Bulk Conductivity ◽  
Probable Number ◽  
A Site

We investigated the bulk electrical conductivity and microbial population distribution in sediments at a site contaminated with light nonaqueous‐phase liquid (LNAPL). The bulk conductivity was measured using in‐situ vertical resistivity probes; the most probable number method was used to characterize the spatial distribution of aerobic heterotrophic and oil‐degrading microbial populations. The purpose of this study was to assess if high conductivity observed at aged LNAPL‐impacted sites may be related to microbial degradation of LNAPL. The results show higher bulk conductivity coincident with LNAPL‐impacted zones, in contrast to geoelectrical models that predict lower conductivity in such zones. The highest bulk conductivity was observed to be associated with zones impacted by residual and free LNAPL. Data from bacteria enumeration from sediments close to the resistivity probes show that oil‐degrading microbes make up a larger percentage (5–55%) of the heterotrophic microbial community at depths coincident with the higher conductivity compared to ∼5% at the uncontaminated location. The coincidence of a higher percentage of oil‐degrading microbial populations in zones of higher bulk conductivity suggests that the higher conductivity in these zones may result from increased fluid conductivity related to microbial degradation of LNAPL, consistent with geochemical studies that suggest that intrinsic biodegradation is occurring at the site. The findings from this study point to the fact that biogeochemical processes accompanying biodegradation of contaminants can potentially alter geoelectrical properties of the subsurface impacted media.

scholarly journals Bacteria and protozoa populations in groundwater in landfill area in São Carlos, SP

1999 ◽  
Vol 30 (3) ◽  
pp. 196-202 ◽  
Author(s):  
Roberta Fusconi ◽  
Mirna Januária Leal Godinho
Keyword(s):  
Heterotrophic Bacteria ◽  
Mean Value ◽  
Microbial Populations ◽  
Most Probable Number ◽  
Plate Method ◽  
Probable Number ◽  
Mean Values ◽  
The Mean ◽  
The Town ◽  
Microaerophilic Conditions

The microbial populations of groundwaters were analyzed in a region under the influence of a landfill (piezometer L12) in the town of São Carlos, São Paulo, Brazil, and in an area not influenced by the landfill (piezometer L5). Heterotrophic bacteria were counted by spread plate method and the number of protozoa was estimated by the most probable number method. There was a larger number of organisms in well L12, with a mean value of 15.76 x 104 CFU/ml for bacteria and 9.7 MPN/ml for protozoa, whereas the mean values for piezometer L5 were 2.88 x 104 CFU/ml for bacteria and 3.4 MPN/ml for protozoa. The greater abundance detected in piezometer L12 may be related to the influence of the leachate through the landfill on the microbial populations, also demonstrated by deoxygenation and by the high conductivity values (3530 µS/cm) compared to piezometer L5 (2.47 mg/L dissolved oxygen and 42 µS/cm conductivity). The most commonly detected protozoa were amoebae and flagellates. The density of flagellate protozoa determined under microaerophilic conditions was 10 times higher than that determined under aerobic conditions.

Measurement of hydrocarbon-degrading microbial populations by a 96-well plate most-probable-number procedure

1996 ◽  
Vol 16 (1) ◽  
pp. 36-41 ◽  
Author(s):  
J R Haines ◽  
B A Wrenn ◽  
E L Holder ◽  
K L Strohmeier ◽  
R T Herrington ◽  
...  
Keyword(s):  
Microbial Populations ◽  
Most Probable Number ◽  
Probable Number
Sign in / Sign up

Export Citation Format

Share Document