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62 records · Page 4Linked to original sources
PubMed2001

In situ detection of cell surface hydrophobicity of probe-defined bacteria in activated sludge.

The surface hydrophobicity of different types of bacteria in activated sludge were investigated under in situ conditions by following the adhesion of fluorescent microspheres with defined surface properties to bacterial surfaces (the MAC-method). This technique was combined with identification of the bacteria with fluorescence in situ hybridization with rRNA-targeted oligonucleotides (FISH) and could thus be used for characterization of surface properties of probe-defined bacteria directly in a complex system without prior enrichment or isolation. This MAC-FISH technique could be used for single bacteria as well as filamentous bacteria. In the investigated activated sludge from an industrial wastewater treatment plant, two types of filamentous bacteria dominated. One morphotype consistently attracted only very few hydrophobic microspheres, indicating that the thin sheath of exopolymers around the cells had a hydrophilic surface. Use of a hierarchical set of gene probes revealed that these filaments were sulphide oxidising Thiothrix spp. The other predominating filamentous morphotype had a thick, very hydrophobic exopolymeric sheath. This filamentous bacterium was found to belong to the alpha-Proteobacteria. The relevance of the significant differences in surface hydrophobicity for the two morphotypes in respect to substrate uptake and floc formation is discussed.

Bacteria↗
PubMed2002

First results from a screening of filamentous organisms present in Buenos Aires's activated sludge plants.

Activated sludge samples from municipal and industry plants were evaluated with the aim to recognise the mainly filamentous bacteria found. The routine tests recommended were performed: Gram, Neisser, PHB-Nilo blue epifluorescence reaction and S. The morphologic characteristics were determined. Correlation between environmental conditions and abundance of dominant bacteria were made. All plants were completely mixed configurations with anoxic reactor for denitrification ahead of main aerobic reactor. Also all systems were working at low F/M values or high sludge age (> ten days) and in some cases with low oxygen concentration. The dominant species were Type 021 N, Thiothrix I, Sphaerotilus natans, Microthrix parvicella, Nocardia sp, Type 1701, Type 1863, Type 0041 and Type 0092.

Actinobacteria↗
PubMed2002

Molecular monitoring of bulking sludge in industrial wastewater treatment plants.

Fluorescent In Situ Hybridisation (FISH) was used to monitor the presence of filamentous microorganisms in industrial wastewater treatment plants (WWTPs). Monitoring with a restricted set of FISH probes in WWTPs from potato industry showed growth and decline of Thiothrix populations that could be linked to operational procedures. In a follow up project new FISH probes were developed for filamentous bacteria in industrial WWTPs and 70 WWTPs were analysed for presence of these filaments. Several newly described species of filamentous bacteria appear to be common and dominant in industrial WWTPs. Monitoring of a WWTP from textile industry showed growth and decline of one of these organisms when operational conditions in the plant were varied. The present paper demonstrates that bulking sludge in industrial wastewater treatment plants can effectively be monitored using a combination of standard chemical analyses and the FISH technique.

In Situ Hybridization, Fluorescence↗
PubMed2004

Occurrence and control of filamentous bulking in aerated wastewater treatment plants of the French paper industry.

The occurrence of filamentous bacteria was investigated in 15 French pulp and paper activated sludge wastewater treatment plant (WWTP). Large filamentous populations were present in most of the plants. Identification carried out with conventional methods based on morphological features and staining techniques showed that the four main filamentous bacteria encountered in these industrial WWTP and responsible for bulking belong to the genera Thiothrix sp., Type 021 N, Haliscomenobacter hydrossis and Type 0092. During two years a specific survey was performed for three of these WWTP showing recurrent bulking phenomena. Data from WWTP performance, chemical data and filaments characterization were compared to correlate the presence of specific filaments with process operating conditions.

Bacteria↗
PubMed2004

Effect of chlorination bulking control on water quality and phosphate release/uptake in an anaerobic-oxic activated sludge system.

This study evaluates the effect of chlorination bulking control on water quality and phosphate release/uptake in an anaerobic-oxic activated sludge system. A series of batch experiments with different specific NaOCl mass dose were conducted to determine the sludge settling properties, supernatant water quality and phosphate metabolism behavior of filamentous bulking sludge. The harvested sludge was from a continuous-flow anaerobic-oxic (A/O) activated sludge pilot-plant, i.e., enhanced biological phosphorus removal (EBPR) system, operated with 15 days of sludge retention time. The filamentous bacteria in the A/O pilot plant were identified to be Thiothrix according to Eikelboom's classification techniques, which was in accordance with the high influent sulfate concentration of this study (50 mg/L sulfate). Increasing NaOCI concentration, as revealed by experimental results, obviously decreased the sludge settling properties (SVI values and zone settling velocities) and meanwhile significantly reduced supernatant water quality (COD, SS, TP) mainly due to higher suspended solids caused by floc disruption. Moreover, the nine-hour batch experiments indicated that high NaOCI dosage (40 mg/gMLSS) completely deteriorated phosphate metabolism of EBPR sludge. Such a high dosage of chlorination further confirmed overdosing through disappearance of intracellular PHB and death of protozoa by microscopic investigation. Still, phosphate release/uptake behavior of EBPR sludge properly functions at low NaOCl dosage (5 mg/g MLSS). Besides, phosphate metabolism worsens rapidly before the SVI value reaches its lowest level. These findings imply that determining NaOCI requirement with merely SVI values can readily result in chlorination overdosing. Proper NaOCI dosage requires a delicately balanced consideration between sludge settling improvement, water quality demand and phosphate metabolism. Batch test of phosphate release/uptake is apparently a prerequisite to conclude an appropriate NaOCl dosage for bulking control.

Bacteria, Anaerobic↗
PubMedDate not supplied

[Microbiological processes in the Lost City vent field, mid-Atlantic ridge].

Microbiological and biogeochemical measurements showed that the intensities of CO2 assimilation, methane oxidation, and sulfate reduction in the Lost City vent field (30 degrees N) reach 3.8 microg C/(1 day), 0.06 microg C/(1 day), and 117 microg S/(1 day), respectively. On the surface of the carbonate structures occurring in this field, two varieties of bacterial mats were found. The first variety, which is specific to the Lost City alkaline vent field, represents jelly bacterial mats dominated by slime-producing bacteria of several morphotypes. This mat variety also contains chemolithotrophic and heterotrophic microorganisms, either microaerobic or anaerobic. The intensities of CO2 assimilation, methane oxidation, and sulfate reduction in this variety reach 747 microg C/(dm3 day), 0.02 microg C/(dm3 day), and 28,000 microg S/(dm3 day), respectively. Bacterial mats of the second variety are formed by nonpigmented filamentous sulfur bacteria, which are close morphologically to Thiothrix. The intensities of CO2 assimilation, methane oxidation, and sulfate reduction in the second mat variety reach 8.2 microg C/(dm3 day), 5.8 microg C/(dm3 day), and 17,000 microg S/(dm3 day), respectively. These data suggest the existence of subsurface microflora in the Lost City vent field.

Atlantic Ocean↗
PubMed1983

[Filamentous bacteria in activated sludge (bulking sludge). I. Occurrence of filamentous bacteria in a sewage treatment plant working with the activated sludge process (plug flow system)].

The occurrence of filamentous bacteria in activated sludge (bulking sludge) was investigated in the sewage treatment plant Berlin-Ruhleben. The studies were carried out in five periods from 26.10.1981 to 29.7.1982 (= 112 sampling days). It was noticed that filamentous bacteria appeared in the aeration tanks in different quantities and several kinds of species. With the identification key from Eikelboom Microthrix parvicella, Type 021 N and Type 0041 were frequently identified in all aeration tanks, whereas Type 0961 and Nocardia spec. were observed only in several aeration tanks. Haliscomenobacter hydrossis, Thiothrix spec., Type 0914, Type 1701, Type 1851 and Type 1852 appeared only sporadically. Besides the familiar filamentous bacteria another species was identified under the microscope which, however, could not be classified so far. The filaments are straight or slightly bent with a visible septation and long cylindrical cells. The species is Gram- and Neisser-negative and shows no deposition of sulfur granules.

Bacteria↗
PubMed1997

Structure and composition of freshwater microbial mats from a sulfur spring ("Font Pudosa", NE Spain).

Different types of microbial mats developing on the wall on a non-thermal sulfur freshwater spring have been studied. Both, light and electron microscopy as well as HPLC analysis of photosynthetic pigments revealed their structure and composition. Prokaryotic chlorophylls and carotenoids helped in the taxonomical assignment of the main photosynthetic groups. "Inverted position" mats (Mat-I) were dominated by Chromatiaceae; they were located closed to the water outlets (0.3 mM sulfide). "Normal position", that is, cyanobacterial-covered mats (Mat-II and Mat-IV), developed elsewhere on the stone walls at lower sulfide concentrations. A third type of mat (Mat-III), covered by chemolithotrophic bacteria, was distinguishable at the water-air interface, strongly attached to the walls of the spring. Up to six physiological types of microorganisms have been recognized: cyanobacteria, Chromatiaceae, purple nonsulfur bacteria. Chlorobiaceae, Chloroflexaceae, and chemolithotrophic bacteria. Cyanobacteria Lyngbya-like, Oscillatoria-like and Pseudanabaena sp. were found. The diversity of Chromatiaceae (six morpho-/pigment types of the genus Chromatium, plus two non identified Chromatiaceae, named PB1 and PB2 were observed) was noticeable. Chemolithotrophic bacteria were represented by the genera Beggiatoa and Thiothrix. Finally, small numbers of Chloroflexus-like bacteria and Chlorobium limicola were found in all the studied mats.

Carotenoids↗