Blanca Pérez-Uz

Dynamics of protozoan and metazoan communities in a full scale wastewater treatment plant by rotating biological contactors

Performance of a full-scale wastewater treatment plant by rotating biological contactors (RBC) system was monitored during a year by physico-chemical and microbial characterisation. Six points along wastewater treatment were selected in the plant: three points along the water line (influent, sedimentation tank and effluent) and three points along RBC system (RBC1, RBC2 and RBC3). Although a large seasonal change in the values of physico-chemical parameters was observed, operation of the plant was optimal during all year (90% of removal in BOD5 and SS influent content). Microbial characterisation was approached by determining the structure and dynamics of protozoan and metazoan communities. Protozoa were the most abundant in all stages in the plant, heterotrophic flagellates being the most representative group in the water line and ciliates in the RBC system. The same seasonal preference was only observed for heterotrophic flagellates in the water line and green flagellates in the RBC system, both groups having highest abundances in summer and spring, respectively. Identification of ciliated protozoa populations rendered 58 species of ciliates in the plant. Most of these species are typical of aerobic wastewater treatment systems except three of them, which are cited for the first time in this type of ecosystems: Chaenea stricta, Holosticha mancoidea and Oxytricha lanceolata. Along the water line 34 species were identified, and half of them only appeared occasionally (once in all the study), while along the RBC system biofilms 55 species were observed, and the majority appeared permanently in this system. Our results indicate that the type of habitat, rather than the physico-chemical water parameters, was the primary factor in determining the different distribution of protozoan and metazoan communities in the plant. In RBC biofilms, the structure of ciliate protozoa community was found to be quite sensitive to changes in physico-chemical parameters, mainly to organic loading (BOD5) variations.

Assessment of plausible bioindicators for plant performance in advanced wastewater treatment systems

Three full-scale advanced biological systems for nitrogen removal showing different efficiencies were assessed during one year, to investigate the protist communities supported in these wastewater treatment plants (WWTP). The main goal of this research was to explore the differences of these communities from those observed in conventional activated sludge systems. The final objective was to provide background support for the proposal of bioindicators in this type of biological systems, where scarce information was available until now, since only conventional systems had been previously studied from this point of view. Results obtained indicate that, in fact, protist population density and diversity in advanced systems for N-elimination are quite different from other wastewater systems studied before. A statistical approach through multivariate analysis was developed to search for association between protist species and physical-chemical system performance, and specifically N-removal efficiencies. The original hypothesis proposing that previous indicators from conventional systems are not adequate in advanced N-removal mechanisms was proved to be correct. Efficient processes on N-removal, despite what it had been usually found in conventional systems, show important flagellate and amoeba populations and these populations tend to reduce their abundances as nitrogen removal performance decreases (moderate to low). Ciliates are however less abundant in these N-removal efficient systems. Certain groups and genera of protist such as flagellates and small amoebae are thus proposed as indicative of high performance N-removal, while in this case the appearance of certain ciliates were indicative of low performance on N- or high organic matter removal (as COD) efficiencies.

Beyond the “Code”: A Guide to the Description and Documentation of Biodiversity in Ciliated Protists (Alveolata, Ciliophora)

Recent advances in molecular technology have revolutionized research on all aspects of the biology of organisms, including ciliates, and created unprecedented opportunities for pursuing a more integrative approach to investigations of biodiversity. However, this goal is complicated by large gaps and inconsistencies that still exist in the foundation of basic information about biodiversity of ciliates. The present paper reviews issues relating to the taxonomy of ciliates and presents specific recommendations for best practice in the observation and documentation of their biodiversity. This effort stems from a workshop that explored ways to implement six Grand Challenges proposed by the International Research Coordination Network for Biodiversity of Ciliates (IRCN‐BC). As part of its commitment to strengthening the knowledge base that supports research on biodiversity of ciliates, the IRCN‐BC proposes to populate The Ciliate Guide, an online database, with biodiversity‐related data and metadata to create a resource that will facilitate accurate taxonomic identifications and promote sharing of data.

Ciliate communities of rotating biological contactor biofilms: a multivariate approach.

Physical-chemical monitoring and characterization of ciliate communities from a full-scale rotating biological system (RBC) have been carried out for a year. RBC system operated efficiently in removing the organic matter, as the decrease of the BOD5 loading along the successive RBC units revealed. 55 species of ciliated protozoa were identified in the RBC biofilms. Differences in abundance, occurrence and type of species were found along the different units of the RBC system; the last RBC held a more stable and diverse ciliate community. The complexity of interspecific relationships among the ciliates has been outlined using multivariate methods (Cluster and Correspondence analysis). Correlation between ciliate species and physical-chemical conditions were obtained by regression analysis. Results show that 12 species of ciliates were related to an optimal efficiency in organic matter removal, Litonotus crystallinus being the most sensitive species. The presence and abundance of Litonotus crystallinus and Acineria uncinata was associated with a decrease in the organic factor. Metopus es was the only species related to a decrease in process efficiency due to its association with an increase in organic factor. The results provide statistical evidence of the use of certain ciliate species as reliable bioindicators in full-scale RBC wastewater treatment plants.

Involvement of Crawling and Attached Ciliates in the Aggregation of Particles in Wastewater Treatment Plants

The biological community in activated sludge wastewater plants is organized within this ecosystem as bioaggregates or flocs, in which the biotic component is embedded in a complex matrix comprised of extracellular polymeric substances mainly of microbial origin. The aim of this work is to study the role of different floc-associated ciliates commonly reported in wastewater treatment plants-crawling Euplotes and sessile Vorticella- in the formation of aggregates. Flocs, in experiments with ciliates and latex beads, showed more compactation and cohesion among particles than those in the absence of ciliates. Ciliates have been shown to contribute to floc formation through different mechanisms such as the active secretion of polymeric substances (extrusomes), their biological activities (movement and feeding strategies), or the cysts formation capacity of some species. Staining with lectins coupled to fluorescein showed that carbohydrate of the matrix contained glucose, manose, N-acetyl-glucosamine and galactose. Protein fraction revealed over the latex beads surfaces could probably be of bacterial origin, but nucleic acids represented an important fraction of the extracellular polymeric substances of ciliate origin.

Morphology and Infraciliature of a Marine Scuticociliate with a Polymorphic Life Cycle: Urocryptum tortum n. gen., n. comb.

Abstract A new genus and species combination are proposed for Urocryptum tortum n. gen., n. comb., a scuticociliate with a polymorphic life cycle. This marine ciliate was isolated from a sample taken at Gokasho Bay in Mie Prefecture (Japan). Specimens from different phases of the growth cycle were examined in vivo and with two silver staining techniques. Three life-history stages were observed: an exponential growth phase stage (trophont), a stationary phase stage (tomite), and finally a resting stage (cyst). The exponential growth form is laterally flattened and ovoid; it has 20–24 somatic kineties (SK) and a typical complement of scuticociliate oral structures. Polykinetid 1 (Pk1) has two longitudinal files of 6 kinetosomes (Ks); sometimes one or two additional kinetosomes are located anteriorly. Polykinetid 2 (Pk2) has two files of 6 or 7 Ks; a third file of three widely spaced kinetosomes is located on its right side, as well as a small curved row of 5 Ks positioned on the right hand side of the posterior end of Pk2. Polykinetid 3 (Pk3) has 3 rows of 4, 5, and 7 Kss perpendicular to the haplokinety (Hk) or paroral membrane. The stationary growth phase cell is spindle-shaped and has a similar number of SK that are much more closely spaced than in exponentially growing specimens. Oral infraciliary structures are reduced in size, having fewer kinetosomes and being positioned more anteriorly in the cell. Pk1 is composed of two files of 5–6 Ks, Pk2 has only two files of 6–7 Ks, and Pk3 has two to three rows of 3–4 Ks. The Hk is displaced anteriorly and becomes straight, losing the shape typical of exponential growth phase cells. Cysts are pyriform with a wide cyst wall; no infraciliary structures were visible.

Morphogenetic processes in division of Uronema filificum Kahl 1931 (Ciliophora: Scuticociliatida) and implications for its systematic position in the family uronematidae

Summary Stomatogenesis in Uronema filificum was studied with pyridinated silver carbonate. Fourteen morphogenetic stages are described. The ontogenetic sequence develops for the proter: haplokinety → haplokinety and scutica; for the opisthe: haplokinety → haplokinety, Ml, M2 and scutica, and scutica → M3. This stomatogenetic pattern is similar to that described for other genera in the same family, but the anlage morphogenetic sequence differs slightly from previous descriptions. The systematic position of Uronema filificum is discussed in the light of the new morphogenetic data reported.

A New Species of the Genus Metacystis (Ciliophora, Prostomatida, Metacystidae) from a Wastewater Treatment Plant

ABSTRACT. Unusual prostomatid specimens were found in the biological reactor of a wastewater treatment plant in a health resort in Valencia, Spain. These ciliates were attached to flocs unlike other free‐swimming prostomatid ciliates described to date in the mixed liquor of activated sludge plants. The morphological study of this species led to a typically different combination of characteristics: elongated cell shape, 20–30 somatic kineties, 2 perioral kineties, and 1 circumoral kinety, 1 large vacuole protruding at the terminal end, a lorica tapered toward the aperture with a smooth neck, and 11–16 annular ridges. These characteristics place this representative as a new species of the genus Metacystis—Metacystis galiani n. sp. This species became the dominant population within the biological reactor when high values of conductivity (4,244 mS/cm) and temperature (26.8 °C) were recorded.

Influencia de la temperatura sobre la asimetría de pilancones en ambiente granítico. Aplicación de un modelo de regresión lineal

Las pilas representan un tipo de forma presente en casi todos los ambientes climaticos. El trabajo estudia el papel de los ciclos termicos como un agente importante del modelado y asimetria que presentan las paredes de las pilas en un clima Mediterra- neo templado - frio. El estudio se ha realizado en el macizo granitico de la Pedriza de Manzanares, zona protegida de gran valor ambiental, incluida en el Parque Nacional de la Sierra de Guadarrama (Madrid, Espana). El analisis de la variabilidad termica mediante modelos de regresion perio- dica multiple, pone de manifiesto la influencia de los ciclos diario y anual en funcion de las orientaciones norte y sur de las paredes de las pilas. Un modelo matematico de regresion lineal muestra como la variabilidad termica diaria influye en la alteracion de las paredes de las pilas, generando superficies planas o de concavidad mas o menos pronunciada. El trabajo tambien establece relaciones entre el grado de alteracion de las diferentes partes de las pilas, con la presencia de liquenes y dureza relativa de la roca. Los resultados avalan la hipotesis de relacion causal entre la variabilidad termica y alteracion de las paredes de las pilas segun su orientacion norte o sur.