Almudena Guinea

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.

Direct Visualization of the Microtubular Cytoskeleton of Ciliated Protozoa with a Fluorescent Taxoid

Abstract Visualization of the infraciliature, which is an essential tool for the identification of ciliate species, has traditionally been obtained with silver proteinate methods. Since infraciliature is mainly composed of microtubules, we used the synthetic fluorescent taxoid FLUTAX as a method for ciliate identification. The main advantages of this method are the facility and rapidity of its application and the fact that no previous fixation and permeabilization processes are required. FLUTAX may also be used as a probe to follow morphogenetical changes in the microtubular cytoskeleton during the ciliate life cycle.

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.

Influence of environmental characteristics on the distribution of ciliates in the River Henares (Central Spain)

We studied the composition, distribution and dynamics of ciliated protozoan communities as well as their relationships with the physical-chemical characteristics of their environment in the River Henares (Central Spain).A total of 67 species belonging to 54 genera were identified. Thirty-four species were subjected to statistical treatment using absence-presence data. Principal component analysis reduced the number of variables to two factors which accounted for 84.73% of total variance. The first axis grouped non-conservative variables, which strongly depended on biological activity. This axis was identified with ‘nutrient status and pollution level’. In contrast, the second factor included conservative variables, poorly influenced by the activity of organisms. This axis was identified with the ‘water mineral content’. From the arrangement of different species of ciliates with regard to these two factors, and using non-hierarchic cluster analysis, we established three different groups with respect to each factor.The saprobiological characterization of the different sampling points indicated that three different stretches can be distinguished in all seasons, and we propose some tentative relationshps between chemical and biological variables which characterize the different levels of saprobity in this river.

Morphology, ultrastructure, and small subunit rDNA phylogeny of the marine heterotrophic flagellate Goniomonas aff. amphinema.

ABSTRACT. Marine goniomonads have a worldwide distribution but ultrastructural information has not been available so far. An isolate of the heterotrophic marine nanoflagellate Goniomonas (G. aff. amphinema) from North Wales (UK) has been studied, providing information on its morphology and cellular structure using video, electron, laser scanning confocal microscopy (LSCM), and atomic force microscopy. Here, we describe a new feature, a granular area, potentially involved in particle capture and feeding. The binding of the lectin wheat germ agglutinin to the granular area of cells with discharged ejectisomes indicates the adhesive nature of this novel feature. The presence of a microtubular intracellular cytopharynx, apparently also used for feeding, has been revealed by LSCM. The small subunit rRNA gene of the isolate has been sequenced (1,788 bp). Phylogenetic results corroborate significant genetic divergence within the marine members of Goniomonas. This work highlights the need for integrated morphological, ultrastructural, and molecular investigation when describing and studying heterotrophic nanoflagellates.

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.

Occurrence of Acineria uncinata in activated sludge plants: morphology and relationship with physico-chemical plant parameters

Summary Acineria uncinata is a common species in the protozoan communities of the activated sludge plants from Madrid Community (Spain). It appears on the floc surface as a small lanceolate ciliate with a characteristic overlapping at the anterior area of the cell. The infraciliature of this species, investigated by silver impregnation and scanning electron microscopy, is composed of seven kineties with different arrangement at both sides of the cell, and a dorsal kinetal segment. The abundance of A. uncinata has been related with the physico-chemical and operational parameters. Correlation analysis showed that A. uncinata can be considered as an indicator of deficient sludge settlement conditions

Microtubular Elements of the Marine Antarctic Ciliate Euplotes focardii (Ciliophora, Hypotrichia)

Summary: Microtubules are the major cytoskeletal component in Euplotes focardii . The spatial organization of the microtubular system of this marine antarctic ciliate is described. Three different methods were employed: immunofluorescence using antitubulin antibodies, scanning electron microscopy, and transmission electron microscopy. The general arrangement of the cytoskeletal microtubular system is similar to that described for temperate species of Euplotes . Basal bodies, microtubular derivatives associated with the kinetosomes and superficial microtubular networks in both dorsal and ventral sides are stable at the low temperatures this species must bear. Slight differences are reported in the disposition of the microtubules on the somatic cortex, As for the oral cytoskeleton the left side infraciliature is reinforced by a complex microtubular system: on the one hand, a developed microtubular network spreading under and among the paramembranelles, and on the other hand microtubules reinforcing the oral crests.

An investigation of the fine structure, cell surface carbohydrates, and appeal of the diatom Extubocellulus sp. as prey for small flagellates

Summary.The fine structure and surface exopolymers of a coastal planktonic nanodiatom of the sparsely reported genus Extubocellulus were studied respectively by scanning electron microscopy and confocal microscopy in conjunction with fluorescent lectins. Monitoring the suitability of the species as prey food for other protists was also investigated by video microscopy coupled with digital film. Cells are rectangular in girdle view, with a pervalvar axis longer than the apical axis. Valves are almost circular with a diameter of 2.8 to 3.6 µm. The valve face bears randomly distributed areolae (ca. 50 in 10 µm), which may be either open or occluded. Two small raised ocelluli occur at the apices, with a rim devoid of perforations and about 6–7 porelli. Glucose and N-acetyl-glucosamine moieties present on the surface of the live diatom were labelled with fluorescent lectins, and a differential pattern of distribution for both carbohydrates was observed. The potential role of fluorescent lectins as cellular probes of taxonomic value in small diatoms is compared with that of nucleotide and antibody probes. We provide the first illustrative evidence of the presence of Extubocellulus sp. in the cytoplasm of the nanoflagellate Goniomonas amphinema and of the egestion of diatom frustules. Results obtained are discussed in the light of the present knowledge of the role of carbohydrate–protein interactions in phagocytosis of prey by free-living protozoa.

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.