Coaggregation among nonflocculating bacteria isolated from activated sludge

Thirty-two strains of nonflocculating bacteria isolated from sewage-activated sludge were tested by a spectrophotometric assay for their ability to coaggregate with one other in two-membered systems. Among these strains, eight showed significant (74 to 99%) coaggregation with Acinetobacter johnsonii S35 while only four strains coaggregated, to a lesser extent (43 to 65%), with Acinetobacter junii S33. The extent and pattern of coaggregation as well as the aggregate size showed good correlation with cellular characteristics of the coaggregating partners. These strains were identified by sequencing of full-length 16S rRNA genes. A. johnsonii S35 could coaggregate with strains of several genera, such as Oligotropha carboxidovorans, Microbacterium esteraromaticum, and Xanthomonas spp. The role of Acinetobacter isolates as bridging organisms in multigeneric coaggregates is indicated. This investigation revealed the role of much-neglected nonflocculating bacteria in floc formation in activated sludge.     

Degradation of substituted thiophenes by bacteria isolated from activated sludge

Actinomycetes were isolated from activated sludge acclimated to thiophene-2-carboxylic acid (T2C) or 5-methyl-thiophene-2-carboxylic acid (T5M2C). These isolates were apparently identical and were identified as strains ofRhodococcus. The strains could grow on T2C, T5M2C, or thiophene-2-acetic acid as sole sources of carbon and energy, but could not use thiophene, methyl thiophenes, several other substituted thiophenes, dibenzothiophene, dimethyl sulfide, or pyrrole-2-carboxylic acid. T2C was degraded quantitatively to sulfate, and its carbon was converted almost entirely to cell biomass and carbon dioxide. Growth yields indicated about 25% conversion of T2C-carbon to cell-carbon. Growth was not supported by thiosulfate or methionine, nor were these compounds oxidized.Rhodococcus strain TTD-1 grown on T2C oxidized both T2C and T5M2C with an apparent K_m of 1.3×10^–5 M. Sulfide was also oxidized by T2C-grown organisms. This is the first demonstration of an actinomycete capable of the complete degradation of thiophene derivatives and of their use by it as sole substrates for growth.     

Isolation of rhodoquinone-containing chemoorganotrophic bacteria from activated sludge

Abstract Several strains of Gram-negative aerobic chemoheterotrophic bacteria which produced rhodoquinone were isolated from activated sludge. All isolates contained a rhodoquinone with eight isoprene units as a major component in addition to the corresponding homologue of ubiquinone. The isolates seemed to make up a single taxon because of their homogeneity in phenotypic and chemotaxonomic properties, but could not be allocated to any known taxa of Gram-negative bacteria.     

Stalked bacteria in activated sludge

Summary A laboratory-scale activated sludge unit was fed continuously with a simulated industrial wastewater, consisting of a dilute solution of inorganic salts, at a rate giving a mean retention time of about 3 days. The system produced a well-settling sludge which on examination by electron microscopy was found to contain considerable numbers of stalked bacteria. These were identified as Caulobacter, which have the ability to attach to surfaces and other organisms by means of a prosthecal holdfast and to flourish in waters with a low content of organic nutrients, and whose occurrence in activated sludge has not apparently been previously recorded. Conditions advantageous to Caulobacter generally prevail in activated sludge systems when these operate in growth phases tending to produce well-settling sludge. Since their holdfast gives Caulobacter the ability to initiate and enlarge microbial clusters by attachment, it is suggested that Caulobacter contribute to microbial floc-formation in activated sludge.     

Isolation of some new sulphur bacteria from activated sludge

E mtiazi , G., H abibi , M.H. & S etareh , M. 1990. Isolation of some new sulphur bacteria from activated sludge. Journal of Applied Bacteriology 69 , 864–870.
During studies on bulking of activated sludge some new sulphur micro-organisms, which were able to grow aerobically and anaerobically on reduced sulphur compounds, were isolated on thiosulphate agar. These were capable of autotrophic and heterotrophic growth on a wide range of substrates. In view of their ability to oxidize reduced sulphur compounds, and because one of them was an oxidase- and catalase-positive, Gram-negative, motile coccus (0.36–0.48 μm) it was named Thiosphaera persica . The second one was an oxidase- and catalase-positive, Gram-negative, motile rod (1.32–1.80 μm) and was named Thiobacillus persica . The third one was oxidase-negative, catalase-positive, motile, Gram-negative and polymorphic and was named Sulphobacter polymorpha .     

Glyphosate degradation byAgrobacterium radiobacter isolated from activated sludge

Summary Two species of bacteria capable of growth onN-phosphonomethylglycine (glyphosate) were isolated from a bench scale sequencing batch reactor degrading a waste stream containing glyphosate. The enrichment and isolation medium contained defined salts and glyphosate as the sole carbon and energy source. Glyphosate was stoichiometrically degraded to aminomethylphosphonic acid (AMPA). The bacteria have been identified asAgrobacterium radiobacter andAchromobacter Group V D.     

Phenol utilisation by fungi isolated from activated sludge

The paper presents the efficiency of phenol removal (concentrations from 500 to 2000 mg/l) by fungi isolated from activated sludge purifying wastewater with high phenol concentration. Five fungal strains were isolated and identified. All isolated strains appeared to be Moniliales from the class of Fungi Imperfecti (Candida sp., Monosporium sp., Trichosporon sp.) Stationary cultures of the individual strains and their mixtures were maintained in Czapek medium containing phenol in concentration from 500 to 2000 mg/l. All isolated strains (except one) were capable of utilising phenol up to a concentration of 1500 mg/l. Depending on investigated strain, phenol in concentration of 500 mg/l was decomposed during 4-25 days, 750 mg/l during 4-14 days. After 20 days, a phenol decline of 1000 mg/l was observed. After 16 days, the phenol decline was 1500 mg/l. Higher phenol concentrations (1500 mg/l) were utilised only by a mixture of two strains. The investigated fungal strains showed good efficiency of phenol removal from high phenol concentration in wastewater and they may be proposed for use in the process of purifying wastewater of this type.     

Optimal dimethyl sulfoxide biodegradation using activated sludge from a chemical plant

Inappropriate biological treatment of dimethyl sulfoxide (DMSO) used by opto-electronics and semi-conductor industries would result in production of malodorous compounds, e.g. dimethyl sulfide, methane-thiol and hydrogen sulfide. The best sludge for DMSO biodegradation was obtained from the activated sludge of a chemical company that used to provide DMSO for the above industries. Under the optimal conditions of pH 7.0–8.5 and 30 °C, the highest removal efficiency in treatment of 500 mg l⁻¹ of DMSO occurred at the rate of 0.078 g DMSO per gram suspended solids per day corresponding to 37 h for complete DMSO biodegradation in a shake-flask culture. However, the time needed for DMSO biodegradation could be reduced to 16 h at the rate of 0.153 g DMSO per gram suspended solids per day if a repeated-batch mode was adopted, indicating that an acclimation period is required by the DMSO degraders. The reaction time could further be shortened to less than 10 h with 95% removal of the 750 mg l⁻¹ DMSO at the maximum rate of 0.909 g DMSO per gram suspended solids per day using an oxygen-enriched air-lift bioreactor. No malodorous compounds, such as dimethyl sulfide, were produced revealing that the biodegradation pathway is oxidative and can solve the odor problems common in the biological wastewater treatment plant of the abovementioned industries.     

Free-living dinitrogen-fixing bacteria isolated from petroleum refinery oily sludge

Dinitrogen-fixing activity (acetylene reduction and N(2) fixation) was found in an oily sludge originating from a petroleum refinery. Two representative dinitrogen-fixing bacterial strains were isolated from this oily waste. Their nitrogenase activity was effective when they were cultivated on sterilized sludge or simple carbon substrates (organic acid salts, sugars). Using the classical methods, these strains could not be unambiguously related to other diazotrophic taxa. The landfarming process is widely used for oily sludge disposal; this study shows that oily sludges are more than a simple carbon input into the soil but that they must also be considered as real sources of dinitrogen-fixing and probably degradative microorganisms.     

活性污泥中群体感应淬灭菌的分离纯化及功能验证

【背景】近年来,群体感应淬灭(Quorum Quenching,QQ)技术在膜生物污堵防控中的应用研究受到了广泛关注。然而,目前已成功分离纯化的高效QQ菌有限,更多高效QQ菌资源亟待挖掘。【目的】从实际运行的膜生物反应器(MembraneBioreactor,MBR)活性污泥中采样,分离并富集高效QQ菌。【方法】以根瘤农杆菌(Agrobacterium tumefaciens) A136为报告菌株,使用指示琼脂平板法测定各菌株的N-辛酰基高丝氨酸内酯(N-Octanoyl-DL-Homoserine Lactone,C8-HSL)降解能力。以紫色色杆菌(Chromobacterium violaceum) VIR24为报告菌株,定量测定所得QQ菌降解N-己酰高丝氨酸内酯(N-Hexanoyl-DL-Homoserine Lactone,C6-HSL)信号分子的能力。通过微生物形态、生理生化及16SrRNA基因序列测定、构建系统发育树、扫描电子显微镜形态观测等方法对菌株进行分类学鉴定。用共培养法分析QQ菌对生物膜形成的抑制能力,通过聚乙烯醇和海藻酸钠包埋固定化QQ菌。【结果】筛选出了6株高效QQ菌,其中对C8-HSL分解能力最强的为杆状、革兰氏阴性戴尔福特菌属(Delftia sp.) JL5。定量分析结果表明菌株JL5能在10 h内完全降解C6-HSL。菌株JL5显著抑制铜绿假单胞菌(Pseudomonas aeruginosa) PAO1和菠萝泛菌(Pantoea ananatis) SK-1生物膜的形成。固定化后的JL5微球仍具有高效的C6-HSL和C8-HSL信号分子分解能力,而且分解速度较被广泛报道的红球菌(Rhodococcussp.)BH4更快。【结论】研究分离得到了高效的QQ菌,能够有效抑制N-酰基高丝氨酸内酯(N-Acyl-HomoserineLactones,AHL)型群体感应菌生物膜的形成,固定化后仍然具有强QQ活性,具备广泛的应用前景,为后续QQ膜生物污堵防控技术的实践应用奠定了基础。     

Lysobacter gilvus sp. nov., isolated from activated sludge

Archives of Microbiology - Strain HX-5-24T was isolated from the sludge collected from the outlet of the biochemical treatment facility of an agricultural chemical plant in Maanshan city, Anhui...     

Instability of the morpholine-degradative phenotype in mycobacteria isolated from activated sludge

The stability of the morpholine-degradative phenotype was studied in a group of nine distinct strains of mycobacteria, all isolated from an activated sludge plant treating morpholine.
Variants incapable of morpholine degradation arose from all strains at high frequency following growth under non-selective conditions. However, strains differed with respect to the frequency at which Mor⁻ variants arose. No spontaneous reversion to wild type could be demonstrated. Six of the nine mycobacterial strains contained plasmids, each had a different plasmid profile. The plasmid profiles of wild type and Mor⁻ variants were compared. In no case could loss of the ability to grow on morpholine be correlated with loss of a complete plasmid. However, evidence is presented which suggests that in two strains loss of the morpholine-degradative phenotype may be correlated with a decrease in the size of a very large plasmid implying deletion of the DNA encoding morpholine degradation. The techniques employed to screen for plasmids in mycobacteria are discussed.     

Polyphosphate-dependent enzymes in some coryneform bacteria isolated from sewage sludge

Abstract Eleven isolates obtained from a laboratory sewage treatment plant, most of them presumptively assigned to the coryneform genera Curtobacterium and Aureobacterium were studied for the presence of intracellular polyphosphates and polyphosphate dependent enzymes. All isolates stored polyphosphates and showed adenylate kinase activities ranging from 64 to 815 mU mg⁻¹. Polyphosphate:AMP phosphotransferase could only be detected in one isolate. Three isolates showed a polyphosphate kinase activity also in minor amounts from 15 to 17 mU mg⁻¹. A polyphosphate dependent NAD or 3-phosphoglycerate kinase could not be detected. Polyphosphate glucokinase activity was measured in cell-free extracts of nine isolates ranging from 2 to 376 mU mg⁻¹. Three isolates showed in addition to the polyphosphate glucokinase, a glucose-6-phosphate-dependent NAD kinase. For the regeneration of NADP from NAD and polyphosphate, this enzyme system may give the isolates a distinct competitive advantage, especially for anabolic processes. The polyphosphate-dependent enzymes reported here may play an additional role in the complex process of 'biological' phosphate removal from wastewater.     

Extraction of activated sludge bacteria exopolymers by ultrasonication

Ultrasonication for the extraction of activated sludge exopolymers was evaluated by total cell count, exopolymer extraction and transmission electron microscopy (TEM). A high deflocculation was achieved after 30 s of sonication in PBS (phosphate-buffered saline). TEM showed that cell lysis was minimal only when sludges were sonicated for 30 s. For sludges sonicated for 30, 90 and 420 s and stained with Ruthenium Red, exopolymers were not extracted on a large scale without considerable cell lysis. Sludges sonicated for 30 s in EDTA gave a larger fraction of damaged cells and also showed copious amounts of attached exopolymers.     

Ecology of bacteriophages infecting activated sludge bacteria.

Little is known about the endemic bacteriophages of activated sludge. In this investigation 49 virus-host systems were studied by isolating co-occurring bacteria and bacteriophages from the aeration basin of a sewage treatment plant during 5 successive weeks. The phage titers were high and fluctuated during the time period. The occurrence of phage-sensitive and -resistant hosts did not depend on the presence or absence of phages. Several phage-host systems expressed variable plating efficiencies. In addition, phages with broad host ranges were observed. These results show that phages are an active part of this ecosystem and that they may exert selection pressure for phage resistance on their bacterial host populations.