Biomedical subjects

V Tandoi

Publications and source records attributed to V Tandoi.

10 recordsLinked to original sources

PubMed2002

PHA storage from several substrates by different morphological types in an anoxic/aerobic SBR.

An activated sludge was cultivated on a mixture of several soluble substrates (acetate, ethanol, glucose, glutamic acid, peptone, Tween 80, starch, yeast extract) in an anoxic/aerobic SBR. Highly dynamic conditions in the SBR (feast famine regime) caused fast removal of most COD in the anoxic phase (in particular acetate, ethanol, glutamic acid and glucose were totally removed) and relevant contribution of storage. In spite of that, filament abundance was always high, as is typical of bulking sludges. Filaments which developed in the reactor were characterized on a morphological basis and on the basis of their ability to grow and to store polyhydroxyalkanoates (PHAs). Three main filaments prevailed in the biocenosis, whose relative abundance was varyng with time: Nostocoida limicola II, (two different morphological types), Haliscomenobacter hydrossis and an unidentified one. It was found that maximum growth rate was higher for flocformers than for filaments on each of the tested substrates. Epifluorescence showed that storage ability was more widespread among flocformers than in the filaments. Only one type of Nostocoida limicola II was able to store PHAs. The obtained data show that aerobic growth on the little residual fraction of COD from the anoxic phase was enough to support high abundance of filamentous microorganisms.

Bioreactors↗

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↗

PubMed2002

Phylogenetic analysis and in situ identification of "Nostocoida limicola"-like filamentous bacteria in activated sludge from industrial wastewater treatment plants.

The diversity of filamentous bacteria present in industrial wastewater treatment plants was analysed by a combination of classical and molecular-biological approaches. Many unknown filamentous bacteria were observed in about 80 screened activated sludge samples from different industries with sometimes severe bulking sludge problems. A special focus was paid to filaments which resembled "Nostocoida limicola", a filamentous bacterium which was found to be present in many WWTPs. These filamentous bacteria are hardly cultivable and only one strain was obtained and maintained in co-culture with a yeast. The 16S rRNA sequences of several other "Nostocoida limicola"-like filamentous bacteria from different sludge samples were obtained by micromanipulation and different molecular-biological methods. The sequences were phylogenetically analyzed and specific molecular probes were developed and applied. The results clearly demonstrate that "Nostocoida limicola"-like filaments from industrial WWTPs are different from all other "Nostocoida limicola" types investigated so far. Our strains are affiliated to the alpha-subclass of Proteobacteria.

DNA Primers↗

PubMed2001

Synthesis of intracellular storage polymers by Amaricoccus kaplicensis, a tetrad forming bacterium present in activated sludge.

AIMS: The study investigated the physiology of Amaricoccus kaplicensis to determine whether it could outcompete polyphosphate accumulating bacteria in activated sludge systems removing phosphorus, by preferentially assimilating substrates in the anaerobic stages of these processes. METHODS AND RESULTS: The storage processes were investigated under anaerobic, anoxic and aerobic conditions in both batch and periodically fed cultures in an aerobic sequencing batch reactor (SBR). Amaricoccus kaplicensis showed a high capacity for storing aerobically large amounts of acetate as poly beta-hydroxybutyrate (PHB) at high rates. However, no acetate assimilation under anaerobic conditions and very slow assimilation under anoxic conditions could be detected. CONCLUSION: Amaricoccus kaplicensis in pure culture does not behave as polyphosphate accumulating bacteria competitor; therefore it is difficult to understand why anaerobic/aerobic systems often contain such large numbers of Amaricoccus cells. SIGNIFICANCE AND IMPACT OF THE STUDY: Amaricoccus kaplicensis is probably not responsible for the failure of activated sludge systems removing phosphorus, and other organisms capable of anaerobic substrate assimilation should be sought.

Acetates↗

PubMed2000

Microbiology of the 'G-bacteria' in activated sludge.

This review discusses a group of bacteria, the 'G-bacteria', which have a distinctive morphology of cocci in tetrads, sheets or clusters, that are seen in large numbers in many activated sludge biomass samples. Isolates of 'G-bacteria' that have been grown axenically are phylogenetically diverse. The Gram-negative members include several alpha- and beta-proteobacteria, among which is the genus Amaricoccus, while the Gram-positive 'G-bacteria' contain several members of the actinobacteria. It is probable that other, as yet uncharacterized, 'G-bacteria' exist in activated sludge. The hypothesis that these 'G-bacteria' are detrimental to the process of enhanced biological phosphate removal by competing for substrates anaerobically with the phosphate-accumulating bacteria in such systems, based as it is largely on mixed-culture studies, receives little support from studies using those available in pure culture. The evidence on which these conclusions are founded is discussed, as are the arguments used to explain why these 'G-bacteria' all appear to thrive under conditions found in certain activated sludge systems.

Actinobacteria↗

PubMed2000

'Candidatus Nostocoida limicola', a filamentous bacterium from activated sludge.

Five strains of 'Candidatus Nostocoida limicola' were isolated by micromanipulation from two activated sludge plants. Two (Ben17 and Ben18) were from Sunbury, Victoria, Australia, and three (Ben67, Ver1 and Ver2) were from Verona, Italy. The near complete 16S rDNA sequences were determined for five strains and the phylogenetic location of this important bulking filament in the actinomycete subphylum is reported for the first time. Phylogenetically, the Ben strains formed one group with 99.4% 16S rDNA similarity, and the Ver strains formed another with 99.9% 16S rDNA similarity. The mean similarity between the two groups was 97.4%. By 16S rDNA comparison, the closest relative to all strains was Terrabacter sp. strain DPO1361 (95.0-95.5% identical). On R2A medium, all strains generally grew as short filaments or clumps of cocci, whereas on glucose sulfide (GS) medium, all grew as irregular twisting filaments comprising Gram-positive and Gram-negative cells, which is close to their in situ morphology. Polyphosphate was stored either as granules (R2A) or throughout the trichomes (GS). None of the strains could grow without added nitrogen, reduce nitrate to nitrogen gas or grow anaerobically, whereas all could grow at 15-30 degrees C, produce catalase and reduce nitrate to nitrite. All were inactive in the Hugh & Leifson test. This paper describes 'Candidatus Nostocoida limicola'.

Actinomycetales↗

PubMed1997

Phenotypic and phylogenetic description of an Italian isolate of "Microthrix parvicella".

"Microthrix parvicella" strain RN1 was isolated from an activated sludge treatment plant in Italy using micromanipulation techniques. The strain grows as thin unbranchedfilaments which are Gram-positive with Neisser-positive granules. The isolate was characterized by analysis of the 16S rDNA which was amplified directly from cell biomass by the polymerase chain reaction and sequenced. "Microthrix parvicella" strain RN1 presents a very high similarity (100%) with another "M. parvicella" strain recently isolated in Australia, suggesting that this micro-organism, a novel, deep branching member of the actinomycetes subphylum, is the same causing the common events of bulking and foaming phenomena in activated sludge treatment plants throughout the world.

DNA, Bacterial↗

PubMed1997

The characterization and description of representatives of 'G' bacteria from activated sludge plants.

The name Tetracoccus cechii is proposed for two strains of the tetrad arranged cocci, previously known as 'G' bacteria, which were isolated from laboratory scale activated sludge plants in the Czech Republic and in Italy. They were morphologically, phenotypically and phylogenetically characterized and found to comprise a novel lineage in the alpha-3 group of the proteobacterial phylum in the domain Bacteria. The strains are Gram-negative and produce intracellular inclusions of poly-beta-hydroxybutyrate. Although commonly seen in activated sludge mixed liquor as cocci 1-2 microns in diameter, arranged in tetrads, in pure culture they can also grow in amorphous aggregations and the cells are generally more variable in their size and shape with coccobacilli as well as cocci being present. They are not able to grow phototrophically, nor can they reduce nitrate beyond nitrite nor grow anaerobically. The closest phylogenetic neighbours of T. cechii are Rhodobacter sphaeroides and R. capsulatus which are 93% similar by 16S rDNA comparison. Tetracoccus cechii is oxidase- and catalase-positive, non-motile and has an optimal growth temperature between 25 degrees and 35 degrees C. The 16S rRNA of T. cechii has a 21 nucleotide deletion in the V9 region (Escherichia coli positions 1258-1278) and this feature is a unique molecular synapomorphy in the alpha-3 group.

Base Sequence↗

PubMed1995

Characterization of an H2-utilizing enrichment culture that reductively dechlorinates tetrachloroethene to vinyl chloride and ethene in the absence of methanogenesis and acetogenesis.

We have been studying an anaerobic enrichment culture which, by using methanol as an electron donor, dechlorinates tetrachloroethene (PCE) to vinyl chloride and ethene. Our previous results indicated that H2 was the direct electron donor for rductive dechlorination of PCE by the methanol-PCE culture. Most-probable-number counts performed on this culture indicated low numbers (< or equal to 10(4)/ml)) of methanogens and PCE dechlorinators using methanol and high numbers (> or equal to 10(6)/ml)) of sulfidogens, methanol-utilizing acetogens, fermentative heterotrophs, and PCE dechlorinators using H2. An anaerobic H2-PCE enrichment culture was derived from a 10(-6) dilution of the methanol-PCE culture. This H2-PCE culture used PCE at increasing rates over time when transferred to fresh medium and could be transferred indefinitely with H2 as the electron donor for the PCE dechlorination, indicating that H2-PCE can serve as an electron donor-acceptor pair for energy conservation and growth. Sustained PCE dechlorination by this culture was supported by supplementation with 0.05 mg of vitamin B12 per liter, 25% (vol/vol) anaerobic digestor sludge supernatant, and 2 mM acetate, which presumably served as a carbon source. Neither methanol nor acetate could serve as an electron donor for dechlorination by the H2-PCE culture, and it did not produce CH4 or acetate from H2-CO2 or methanol, indicating the absence of methanogenic and acetogenic bacteria. Microscopic observatios of the pruified H2-PCE culture showed only two major morphotypes: irregular cocci and small rods.

Acetates↗

PubMed1971

[Not Available].

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History, Ancient↗