Characterization of caulobacters isolated from wastewater treatment systems.

Caulobacters are generally assumed to be found only in environments of low organic content; however, we readily isolated strains from a variety of sewage treatment system designs and locations, and 33 distinct strains were characterized. Most were morphologically similar, having the crescent-shaped cell body, short stalk, and hexagonally packed, paracrystalline surface (S) layer characteristic of several Caulobacter crescentus laboratory strains. Upon closer examination, they were distinguishable on the basis of protein band profiles on polyacrylamide gel electrophoresis, gross colony characteristics, or holdfast composition or by DNA restriction fragment length polymorphism analysis with flagellin and S-layer gene probes. Most of the isolates contained one or more high-molecular-weight plasmids and were resistant to a number of antibiotics, characteristics generally not shared with caulobacters isolated from other sources. Six of the 33 strains were retained because they did not fit the typical isolate profile; these strains are overrepresented in our collection compared with their relative proportion in wastewater treatment systems. By colony hybridization and restriction fragment length polymorphism analysis, all of these and one typical isolate showed less homology than the others to the surface array gene of a laboratory strain (C. crescentus CB15), and three hybridized less strongly with the flagellin gene from the same strain. In sum, although the strains were distinguishable, caulobacters from the wastewater treatment systems we examined were relatively homogenous, were similar to characterized laboratory strains, and, with exceptions, could probably be reliably detected as a group by gene probes derived from C. crescentus strains.     

Characterization of new denitrifying Rhodobacter strains isolated from photosynthetic sludge for wastewater treatment

New denitrifying strains of phototrophic bacteria isolated from photosynthetic sludge reactors for wastewater treatment were characterized. All of the new isolates were mesophilic, nonhalophilic, facultative photoheterotrophs that were able to grow by anaerobic photosynthesis, aerobic respiration, or nitrate respiration. They had ovoid cells that were motile by single polar flagella, formed vesicular photosynthetic membranes together with bacteriochlorophyll a and carotenoids of the spheroidene series, required biotin, thiamine, and biotin as growth factors, and utilized a wide variety of organic compounds as electron donor and carbon sources. In these respects, the isolates most closely resembled Rhodobacter sphaeroides. However, they differed from this species in utilizing malonate and dulcitol but not tartrate as carbon sources and in their inability to grow anaerobically in darkness with trimethylamine N-oxide or dimethylsulfoxide as a terminal oxidant. Partial sequencing of 16S rRNA genes provided evidence for genetic differences between the new isolates and R. sphaeroides or other members of the genus Rhodobacter. Activities of nitrate reductase, nitrite reductase, and nitrous oxide reductase were detected in intact cells of one of the new isolates. All these enzyme activities were induced by cultivation with nitrate.     

Characterization of plastic degrading bacteria isolated from sewage wastewater

Plastic is a fundamental polymer used in routine life and disposed of in sewage. It leads to microplastic pollution in aquatic organisms, introducing it into the food chain and affecting human health. In the present study, samples were collected from sewage wastewater to isolate the bacteria that could potentially reduce plastic. The six samples were incubated with plastic pieces in minimal salt media for 120 days. After 120 days, the weight loss experiment showed that samples SH5B and SH6B degraded 25% plastic. After chemical and molecular characterization, these strains were identified as Pseudomonas sp. SH5B and Pseudomonas aeruginosa SH6B. The Fourier-transform infrared spectroscopy (FTIR) analysis showed peaks shifting, indicating bond stretching, bond bending, and new bond formation. The Gas Chromatography-Mass Spectrometry (GC–MS) analysis revealed various new compounds produced during plastic degradation by these bacterial strains. The plastic biodegradation potential makes these bacteria an impending foundation for green chemistry to eradicate tough pollutants from the environment.     

Energy from vascular plant wastewater treatment systems

Water hyacinth (Eichhornia crassipes), duckweed (Spirodela sp. andLemna sp.), water pennywort (Hydrocotyle ranunculoides), and kudzu (Pueraria lobata) were anaerobically fermented using an anaerobic filter technique that reduced the total digestion time from 90 d to an average of 23 d and produced 0.14-0.22 m³ CH₄/kg (dry weight) (2.3-3.6 ft³/lb) from mature filters for the 3 aquatic species. Kudzu required an average digestion time of 33 d and produced an average of 0.21 m³ CH₄/kg (dry weight) (3.4 ft³/lb). The anaerobic filter provided a large surface area for the anaerobic bacteria to establish and maintain an optimal balance of facultative, acid-forming, and methane-producing bacteria. Consequently the efficiency of the process was greatly improved over prior batch fermentations.     

Modification of norfloxacin by a Microbacterium sp. strain isolated from a wastewater treatment plant

Antimicrobial residues found in municipal wastewater may increase selective pressure on microorganisms for development of resistance, but studies with mixed microbial cultures derived from wastewater have suggested that some bacteria are able to inactivate fluoroquinolones. Medium containing N-phenylpiperazine and inoculated with wastewater was used to enrich fluoroquinolone-modifying bacteria. One bacterial strain isolated from an enrichment culture was identified by 16S rRNA gene sequence analysis as a Microbacterium sp. similar to a plant growth-promoting bacterium, Microbacterium azadirachtae (99.70%), and a nematode pathogen, "M. nematophilum" (99.02%). During growth in medium with norfloxacin, this strain produced four metabolites, which were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and nuclear magnetic resonance (NMR) analyses as 8-hydroxynorfloxacin, 6-defluoro-6-hydroxynorfloxacin, desethylene norfloxacin, and N-acetylnorfloxacin. The production of the first three metabolites was enhanced by ascorbic acid and nitrate, but it was inhibited by phosphate, amino acids, mannitol, formate, and thiourea. In contrast, N-acetylnorfloxacin was most abundant in cultures supplemented with amino acids. This is the first report of defluorination and hydroxylation of a fluoroquinolone by an isolated bacterial strain. The results suggest that some bacteria may degrade fluoroquinolones in wastewater to metabolites with less antibacterial activity that could be subject to further degradation by other microorganisms.     

Characterization of mucoid Pseudomonas aeruginosa strains isolated from technical water systems

The occurrence of mucoid Pseudomonas aeruginosa strains was investigated in water samples and surface material from non-clinical aquatic environments. Ten of 81 environmental isolates displayed a mucoid colony type after incubation at 36°C for 24 h on Pseudomonas Isolation Agar. The mucoid strains obtained exclusively from surfaces of technical water systems were characterized in terms of medium-dependent expression of mucoid colonial phenotype, exoenzyme profile, pigment production and O-antigen type. The mucoid strains secreted substantially higher quantities of carbohydrate and uronic acid-containing material compared to non-mucoid environmental isolates. Major slime components of the mucoid strains were identified as O-acetylated alginates that contained higher proportions of mannuronate than guluronate monomer residues and were composed of blocks of poly-mannuronate and poly-mannuronate/guluronate, whereas blocks of poly-guluronate were absent. The results suggest that surfaces in aquatic environments may represent a natural habitat for mucoid (i.e. alginate-overproducing) strains of Ps. aeruginosa with properties similar to clinical mucoid strains.     

Comamonas granuli sp. nov., isolated from granules used in a wastewater treatment plant

A Gram-negative, motile, rod-shaped, non-spore-forming bacterial strain, designated as Ko03(T), was isolated from microbial granules, and was characterized, using a polyphasic approach, in order to determine its taxonomic position. The isolate was positive for catalase and oxidase, but negative for gelatinase and beta-galactosidase. Phylogenetic analyses using the 16S rRNA gene sequence showed that the strain formed a monophyletic branch towards the periphery of the evolutionary radiation occupied by the genus Comamonas, its closest neighbors being Comamonas koreensis KCTC 12005(T) (95.9% sequence similarity), Comamonas nitrativorans DSM 13191(T) (95.7%), and Comamonas odontotermitis LMG 23579(T) (95.7%). Strain Ko03(T) had a genomic DNA G+C content of 68.4 mol% and the predominant respiratory quinone was Q-8. The major fatty acids were C(16:1) omega7c (44.7%), C(16:0) (28.1%), C(18:1) (16.1%), and C(10:0) 3-OH (3.5%). These chemo-taxonomic results supported the affiliation of strain Ko03(T) to the genus Comamonas. However, low 16S rRNA gene sequence similarity values and distinguishing phenotypic characteristics allowed genotypic and phenotypic differentiation of strain Ko03(T) from recognized Comamonas species. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain Ko03(T) represents a novel species of the genus Comamonas, for which the name Comamonas granuli sp. nov. is proposed. The type strain is Ko03(T) (= KCTC 12199(T) = NBRC 101663(T)).     

Characterization of pseudomonads isolated from diseased fleece.

A total of 59 Pseudomonas isolates was obtained from 11 samples of diseased fleece taken from live sheep. All but four of the isolates could be assigned to one of nine Pseudomonas species, of which P. aeruginosa, P. alcaligenes, P. mendocina , and P. putida were the most common. P. aeruginosa was found in four of the fleece samples and, when present, appeared to predominate. Although several of the isolates of P. aeruginosa lacked the ability to produce pyocyanin (and some produced neither pyocyanin nor fluorescein), nearly all produced several virulence factors. Of the other pseudomonads, many produced proteinase, esterase, and catalase, several were able to grow at 42 degrees C and reduce nitrate, and some also produced lipase and hemolysin and, like P. aeruginosa, might serve to initiate (or sustain) the dermatitis frequently associated with fleece rot in sheep.     

Anaerobic digestion and wastewater treatment systems

Upflow Anaerobic Sludge Bed (UASB) wastewater (pre-)treatment systems represent a proven sustainable technology for a wide range of very different industrial effluents, including those containing toxic/inhibitory compounds. The process is also feasible for treatment of domestic wastewater with temperatures as low as 14–16° C and likely even lower. Compared to conventional aerobic treatment systems the anaerobic treatment process merely offers advantages. This especially is true for the rate of start-up. The available insight in anaerobic sludge immobilization (i.e. granulation) and growth of granular anaerobic sludge in many respects suffices for practice. In anaerobic treatment the immobilization of balanced microbial communities is essential, because the concentration of intermediates then can be kept sufficiently low.So far ignored factors like the death and decay rate of organisms are of eminent importance for the quality of immobilized anaerobic sludge. Taking these factors into account, it can be shown that there does not exist any need for phase separation when treating non- or slightly acidified wastewaters. Phase separation even is detrimental in case the acidogenic organisms are not removed from the effluent of the acidogenic reactor, because they deteriorate the settleability of granular sludge and also negatively affect the formation and growth of granular sludge. The growing insight in the role of factors like nutrients and trace elements, the effect of metabolic intermediates and end products opens excellent prospects for process control, e.g. for the anaerobic treatment of wastewaters containing mainly methanol.Anaerobic wastewater treatment can also profitably be applied in the thermophilic and psychrophilic temperature range. Moreover, thermophilic anaerobic sludge can be used under mesophilic conditions.The Expanded Granular Sludge Bed (EGSB) system particularly offers big practical potentials, e.g. for very low strength wastewaters (COD 1 g/l) and at temperatures as low as 10° C. In EGSB-systems virtually all the retained sludge is employed, while compared to UASB-systems also a substantially bigger fraction of the immobilized organisms (inside the granules) participates in the process, because an extraordinary high substrate affinity prevails in these systems. It looks necessary to reconsider theories for mass transfer in immobilized anaerobic biomass.Instead of phasing the digestion process, staging of the anaerobic reactors should be applied. In this way mixing up of the sludge can be significantly reduced and a plug flow is promoted. A staged process will provide a higher treatment efficiency and a higher process stability. This especially applies for thermophilic systems.     

Antimicrobial resistance patterns in Enterobacteriaceae isolated from an urban wastewater treatment plant

Over 18 months, enterobacteria were isolated from the raw (189 isolates) and treated (156 isolates) wastewater of a municipal treatment plant. The isolates were identified as members of the genera Escherichia (76%), Shigella (7%), Klebsiella (12%) and Acinetobacter (4%). Antimicrobial susceptibility phenotypes were determined using the agar diffusion method for the antibiotics amoxicillin, gentamicin, ciprofloxacin, sulfamethoxazole/trimethoprim, tetracycline and cephalothin, the disinfectants hydrogen peroxide, sodium hypochlorite, quaternary ammonium/formaldehyde and iodine, and the heavy metals nickel, cadmium, chromium, mercury and zinc. Class 1 integrons were detected by PCR amplification using the primers CS5 and CS3. Compared with the raw influent, the treated wastewater presented higher relative proportions of Escherichia spp. isolates resistant to ciprofloxacin and cephalothin (P<0.0001 and P<0.05, respectively). Except for mercury, which showed a positive correlation with tetracycline and sulfamethoxazole/trimethoprim, no significant positive correlations were observed between antibiotic, disinfectant and heavy metal resistance. The variable regions of class 1 integrons, detected in c. 10% of the Escherichia spp. isolates, contained predominantly the gene cassettes aadA1/dhfrI.     

Airborne coliphages from wastewater treatment facilities.

The emission (from wastewater treatment plants) of airborne coliphages that form plaques on two strains of Escherichia coli was investigated. Two activated-sludge and two trickling-filter plants were studied. Field sampling procedures used large-volume air samplers with recirculation devices. Coliphages were enumerated by a most-probable-number (MPN) procedure. Temperature, relative humidity, windspeed, and presence of sunlight were monitored. Concurrent samples of sewage were taken during each air-sampling run. Average coliphage levels in the airborne emissions of trickling-filter beds and activated-sludge units were 2.84 X 10(-1) and 3.02 X 10(-1) MPN/m3, respectively, for all positive observations, and sewage liquor concentrations from the sources were 4.48 X 10(5) and 2.94 X 10(6) plaque-forming units/liter, respectively, depending upon the E. coli host used for assay. This work establishes minimal airborne-coliphage concentrations from the plants studied. The procedures employed will be useful in evaluating the animal virus levels in these emissions.     

Airborne coliphages from wastewater treatment facilities.

The emission (from wastewater treatment plants) of airborne coliphages that form plaques on two strains of Escherichia coli was investigated. Two activated-sludge and two trickling-filter plants were studied. Field sampling procedures used large-volume air samplers with recirculation devices. Coliphages were enumerated by a most-probable-number (MPN) procedure. Temperature, relative humidity, windspeed, and presence of sunlight were monitored. Concurrent samples of sewage were taken during each air-sampling run. Average coliphage levels in the airborne emissions of trickling-filter beds and activated-sludge units were 2.84 X 10(-1) and 3.02 X 10(-1) MPN/m3, respectively, for all positive observations, and sewage liquor concentrations from the sources were 4.48 X 10(5) and 2.94 X 10(6) plaque-forming units/liter, respectively, depending upon the E. coli host used for assay. This work establishes minimal airborne-coliphage concentrations from the plants studied. The procedures employed will be useful in evaluating the animal virus levels in these emissions.     

Production and characterization of bioflocculants from bacteria isolated from wastewater treatment plant in South Africa

Bioflocculants produced by six bacteria obtained from activated sludge at a wastewater treatment plant were quantified, purified, and characterized. Effects of pH, temperature, cationic salt content, and specific potential inhibitors on the flocculating activities of the bioflocculants were also determined. Bioflocculants produced by the different bacterial isolates ranged between 6.33 and 27.66 g/L in concentration and were composed of both carbohydrate and protein in varying amounts, as well as a relatively high concentration of uronic acid. The flocculating activity of the broth culture increased during the logarithmic phase of bacterial growth with a maximum ranging from 2.395 to 3.709/OD. Optimum pH for the flocculating activity of the bioflocculants was between 8 and 9, with generally higher flocculating activity observed at 28°C. Of the cations tested, Mg²⁺ and Mn²⁺ improved flocculating activity up to 5.2 fold. The stability of these bacterial bioflocculants under various environmental and nutritional conditions suggests their possible use in the industries and environmental applications. Therefore, this study details important implications in providing a safer alternative flocculation method for wastewater treatment.     

Characterization of beta-D-galactosidase isolated from I-cell disease liver.

The residual beta-D-galactosidase activity (10% of normal) present in an autopsy sample of liver derived from an I-cell patient has been characterized. The pH optima for both I-cell and normal acid 4-methylumbelliferyl beta-D-galactoside activities were 4.35. The adsorption and elution profiles of the I-cell enzyme from Con A-Sepharose were similar to those of normal liver beta-D-galactosidase. Although starch gel electrophoresis revealed the presence of beta-D-galactosidase A and B in I-cell disease liver, the A band was more diffuse and migrated less anodally than the A band from normal liver. The electrophoretic mobilities of both I-cell and normal beta-D-galactosidase A appeared to decrease after treatment with neuraminidase. Kinetic studies of the I-cell and normal level beta-D-galactosidase demonstrated similar apparent Km values with respect to the 4-methylumbelliferyl beta-D-galactoside and Gm1 ganglioside, whereas the Vmax values obtained for the I-cell enzyme were 10- to 12-fold lower than those of the normal enzyme for both substrates.     

Characterization of coagulase-positive staphylococci isolated from free-living birds.

A total of 129 coagulase-positive staphylococcal strains were isolated from the nasopharyngeal region of free-living birds--81 (16%) from 501 birds of prey, 29 (25%) from 117 water birds, and 19 (2%) from 937 pheasants. Staphylococcus aureus and Staphylococcus intermedius were identified in 64 (79%) and 17 (21%) strains from birds of prey, in 1 (3%) and 28 (97%) strains from water birds, and in 4 (21%) and 15 (79%) strains from pheasants, respectively. Of the total number of the 69 S.aureus strains 45 (65%) could be biotyped. Biotype D prevailed in the strains from birds of prey. Among all the 60 S.intermedius strains 41 (68%) biotype 1 and 19 (32%) biotype 3 strains could be recognized. Biotype 1 predominated in strains from water birds and pheasants, while biotype 3 in strains from birds of prey. Resistance to antibiotics was recorded in 8 (12%) S.aureus and 5 (8%) S.intermedius strains only. Fifty-six (81%) of the 69 S.aureus strains could be typed with human phages, 30 (44%) with bovine and 41 (51%) with chicken phages. It is evident that the host range of Shimizu's (CH) phages involves not only S.aureus from chicken but also from any other birds. None of these strains was typable with canine phages. Out of the 60 S.intermedius strains 45 (75%) were lysed with Blouse and Meekins' canine phages. When human, bovine, and chicken phages were used, all the 60 strains were completely resistant.     

Characterization and biological treatment of ceramic industry wastewater

Ceramic industry wastewaters not only contain high suspended and total solids but also significant amounts of dissolved organics resulting in high BOD or COD loads. Suspended solids can be removed from the wastewater by chemical precipitation. However, dissolved BOD/COD compounds can only be removed by biological or chemical oxidation. Effluent wastewater from chemical sedimentation stage of EGE CERAMIC industry was characterized and subjected to biological treatment in a laboratory scale activated sludge unit. Experiments were conducted at different hydraulic and solids retention times. The best results were obtained with Š_c=20 h of hydraulic and Š_c=20 days of solids retention times (sludge age) resulting in effluent COD concentration of 40 mg/l from a feed wastewater of 720 mg/l COD content. The suspended solids content of the activated sludge effluent was approximately 52 mg/l.     

Characterization and biological treatment of pickling industry wastewater

Pickling industry wastewaters present unique difficulties in biological treatment because of high salt content (3–6% salt). Conventional activated sludge cultures disintegrate or loose microbial activity as a result of plasmolysis at salt concentrations above 1%. In order to overcome adverse effects of salt in pickling wastewater, salt tolerant bacteria (Halobacter halobium) was added to activated sludge culture and used in biological treatment of the wastewater in an activated sludge unit. After characterization and nutrient balancing of the wastewater, an activated sludge unit was used in laboratory to investigate the effects of major process variables such as sludge age and hydraulic residence time on performance of the system. Single stage and two stage activated processes were used for the treatment of the pickling wastewater. More than 95% of COD removal was obtained with a single stage process at a sludge age of θ_c=10?d and hydraulic residence time of θ_H=30?h. Similar results were obtained with the two stage process, when sludge ages and hydraulic residence times for each stage were θ_c1=θ_c2=10?d, and θ_H1=θ_H2=15?h, respectively. Kinetic coefficients were determined and the design equations were developed by using the experimental data.