Degradation of mixtures of monochlorophenols and phenol as substrates for free and immobilized cells of Alcaligenes sp. A7-2

Summary The biodegradation of the three isomeric monochlorophenols 2-(2CP), 3- (3CP) and 4-chlorophenol (4CP) and phenol by the constructed strain Alcaligenes sp. A7-2 was investigated. Mineralization took place in the order: phenol >4CP >2CP >3CP, whereas 3CP was mineralized only co-metabolically. In substrate mixtures with phenol, degradation of 4CP was decelerated but degradation of 2CP was accelerated. Free cells in batch culture showed biphasic growth with an equimolar mixture of 2CP and 4CP as substrates, perhaps due to diauxie. Degradation patterns obtained with free cells in batch culture were confirmed with immobilized cells in continuous culture. Immobilized cells of Alcaligenes sp. A7-2 built up a biofilm on the lava that was used as filling material in the packed-bed reactors. The continuous cultures remained stable despite increasing input rates of chlorophenol and phenol mixtures up to 1.16 mMo1.1^–1.h^–1 for several weeks. Correspondence to: H.-J. Rehm     

Biodegradation of the herbicide propanil, and its 3,4-dichloroaniline by-product in a continuously operated biofilm reactor

The persistence of propanil in soil and aquatic environments along with the possible accumulation of toxic degradation products, such as chloroanilines, is of environmental concern. In this work, a continuous small-scale bioprocess to degrade the herbicide propanil, its main catabolic by-product, 3,4-dichloroaniline (3,4-DCA), and the herbicide adjuvants is carried out. A microbial consortium, constituted by nine bacterial genera, was selected. The isolated strains, identified by amplification and sequencing of their 16S rDNA, were: Acidovorax sp., Luteibacter (rhizovicinus), Xanthomonas sp., Flavobacterium sp., Variovorax sp., Acinetobacter (calcoaceticus), Pseudomonas sp., Rhodococcus sp., and Kocuria sp. The ability of the microbial consortium to degrade the herbicide was evaluated in a biofilm reactor at propanil loading rates ranging from 1.9 to 36.8 mg L^?1 h^?1. Complete removal of propanil, 3,4-DCA, chemical oxygen demand and total organic carbon was obtained at propanil loading rates up to 24.9 mg L^?1 h^?1. At higher loading rates, the removal efficiencies decayed. Four of the identified strains could grow individually in propanil, and 3,4-DCA: Pseudomonas sp., Acinetobacter calcoaceticus, Rhodococcus sp., and Xanthomonas sp. The Kokuria strain grew on 3,4-DCA, but not on propanil. The first three bacteria have been related to biodegradation of phenyl urea herbicides or chlorinated anilines. Although some strains of the genera Xanthomonas and Kocuria have a role in the biodegradation of several xenobiotic compounds, as far as we know, there are no reports about degradation of propanil by Xanthomonas or 3,4-DCA by Kocuria species.     

The potential for hydrocarbon biodegradation and production of extracellular polymeric substances by aerobic bacteria isolated from a Brazilian petroleum reservoir

Extracellular polymeric substances (EPS) can contribute to the cellular degradation of hydrocarbons and have a huge potential for application in biotechnological processes, such as bioremediation and microbial enhanced oil recovery (MEOR). Four bacterial strains from a Brazilian petroleum reservoir were investigated for EPS production, emulsification ability and biodegradation activity when hydrocarbons were supplied as substrates for microbial growth. Two strains of Bacillus species had the highest EPS production when phenanthrene and n-octadecane were offered as carbon sources, either individually or in a mixture. While Pseudomonas sp. and Dietzia sp., the other two evaluated strains, had the highest hydrocarbon biodegradation indices, EPS production was not detected. Low EPS production may not necessarily be indicative of an absence of emulsifier activity, as indicated by the results of a surface tension reduction assay and emulsification indices for the strain of Dietzia sp. The combined results gathered in this work suggest that a microbial consortium consisting of bacteria with interdependent metabolisms could thrive in petroleum reservoirs, thus overcoming the limitations imposed on each individual species by the harsh conditions found in such environments.     

Ecology of rotifers of Surinsar,a subtropical,fresh water lake in Jamme (J & K), India

17 species of rotifers have been recorded from Lake Surinsar, Jammu (J & K), India of which some are either exclusively limnetic (Brachionus angularis, Hexarthra sp., Filinia opliensis), or littoral (Brachionus patulus, M. ventralis, Trichotoria sp., Platyias quadricornis, Lecane (Monostyla) decipiens, L (M), bulla and Lecane sp.) and others (Keratella tropica, Anuraeopsis fissa, Brachionus quadridentatus, B. calyciflorus, Trichocera sp., T. similis, and Polyarthra sp.) seem to be wandering species. Seasonal maxima for both littoral and limnetic zones are reported. Most population maxima are contributed mainly by one or at best two species.Physico-chemical factors like temperature, pH, dissolved oxygen, free carbon dioxide, calcium, magnesium, and total alkalinity have been studied and their infuence on these rotifer species are discussed. On their thermal responses, the available rotifer species have been classified as warm stenothermal, cold stenothermal or eurythermal. The importance of Mytilina ventralis as a biological indicator for dissolved oxygen in this lake has been pointed out.     

BIODEGRADABILITY OF HYDROCARBONS BY CYANOBACTERIA1

Five cyanobacterial species (Phormidium sp., Nostoc sp., Anabaena sp. Aphanothece conferta, and Synechocystis aquatilis) isolated from the Suez Canal coast at the city of Ismailia (Egypt) were tested for biodegradation of four hydrocarbon (HC) compounds: two aliphatic compounds (n‐octadecane and pristine) and two aromatic compounds (phenanthrene and dibenzothiophene). High degradation efficiencies for the two aliphatic compounds were measured for A. conferta (64% for n‐octadecane and 78% for pristine) and S. aquatilis (85% for n‐octadecane and 90% for pristane). However, the other biodegradation percentages ranged between weak and moderate percentages.     

Biodegradation of Dichloromethane in an Estuarine Environment

Dichloromethane (DCM) is a toxic pollutant showing prolonged persistence in water. So far, biodegradation of DCM has only been reported in soils and freshwater systems. Herein, we studied whether or not biodegradation of DCM could occur in estuarine waters. Results showed over 90% mineralization of DCM in natural estuarine waters supplemented with DCM. Biodegradation of DCM in estuarine waters occurred by association of different bacterial species. Generally, two bacterial species participated in DCM degradation. Two bacterial consortia were obtained. Consortia were able to degrade around 80% of DCM in about 6 days. The species involved in the process were identified by 16S rRNA gene sequencing; a consortium was constituted by Pseudomonas sp. and Brevundimonas sp. and a second consortium was formed by Pseudomonas sp. and an Acinetobacter sp. Our results showed that DCM can be readily biodegraded in estuarine waters.     

Microbial degradation of pentachlorophenol

Pentachlorophenol (PCP) was the most prevalent wood preservative for many years worldwide. Its widespread use had led to contamination of various environments. Traditional methods of PCP clean-up include storage in land-fill sites, incineration and abiotic degradation processes such as photodecomposition. Some aerobic and anaerobic microorganisms can degrade PCP under a variety of conditions. Axenic bacterial cultures, Flavobacterium sp., Rhodococcus sp., Arthrobacter sp., Pseudomonas sp., Sphingomonas sp., and Mycobacterium sp., and fungal cultures, Phanerochaete sp. and Trametes sp. exhibit varying rates and extent of PCP degradation. This paper provides some general information on properties of PCP and reviews the influence of nutrient amendment, temperature and pH on PCP degradation by various aerobic and anaerobic microorganisms. Where information is available, proposed degradation pathways, intermediates and enzymes are reviewed.     

Microbial Metabolism of Quinoline by Comamonas sp.

An aerobic bacterial strain which can use quinoline as the sole carbon and energy source has been isolated from activated sludge and identified as Comamonas sp. The microbial metabolism of quinoline by this strain has been investigated. A pH 8 and a temperature of 30 °C were the optimum degradation conditions of quinoline. Five intermediates including 2-oxo-1,2-dihydroquinoline, 5-hydroxy-6-(2-carboxyethenyl)-1H-2-pyridone, 6-hydroxy-2-oxo-1,2-dihydroquinoline, 5,6-dihydroxy-2-oxo-1,2-dihydroquinoline, and 8-hydroxy-2-oxo-1,2-dihydroquinoline were found during quinoline biodegradation. The presence of these intermediates suggested that at least two pathways were involved for quinoline degradation by Comamonas sp. and a reasonable degradation route was proposed to account for the intermediates observed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Lignin biodegradation and ligninolytic enzyme studies during biopulping of Acacia mangium wood chips by tropical white rot fungi

White rot fungi are good lignin degraders and have the potential to be used in industry. In the present work, Phellinus sp., Daedalea sp., Trametes versicolor and Pycnoporus coccineus were selected due to their relatively high ligninolytic enzyme activity, and grown on Acacia mangium wood chips under solid state fermentation. Results obtained showed that manganese peroxidase produced is far more compared to lignin peroxidase, suggesting that MnP might be the predominating enzymes causing lignin degradation in Acacia mangium wood chips. Cellulase enzyme assays showed that no significant cellulase activity was detected in the enzyme preparation of T. versicolor and Phellinus sp. This low cellulolytic activity further suggests that these two white rot strains are of more interest in lignin degradation. The results on lignin losses showed 20–30% of lignin breakdown at 60 days of biodegradation. The highest lignin loss was found in Acacia mangium biotreated with T. versicolor after 60 days and recorded 26.9%, corresponding to the percentage of their wood weight loss recorded followed by P. coccineus. In general, lignin degradation was only significant from 20 days onwards. The overall percentage of lignin weight loss was within the range of 1.02–26.90% over the biodegradation periods. Microscopic observations conducted using scanning electron microscope showed that T. versicolor, P. coccineus, Daedalea sp. and Phellinus sp. had caused lignin degradation in Acacia mangium wood chips.     

Biodegradation of wood in crude oil-polluted soil

A field investigation (April–November) in Nigeria showed that biodegradation of obeche (Triplochiton scleroxylon) wood blocks was initially retarded in crude oil-contaminated soil but later became enhanced as indicated by loss of compression resistance. Further indication of this pattern was the detection of soft-rot cavities and basidiomycete fungi after 2–3 months exposure when compared to control blocks in uncontaminated soil. Laboratory tests with Pleurotus sp., Trametes sp., Gloeophyllum sp. (basidiomycetes) and Chaetomium sp. (soft-rot fungus) confirmed that degradation of crude oil-coated obeche blocks was markedly retarded without the presence of hydrocarbon-degrading bacteria. The filtrate of hydrocarbon-degrading Pseudomonas sp. grown in mineral salt/crude oil medium for 3–4 weeks supported growth of the test fungi better than in carboxymethyl cellulose medium but less than in potato dextrose broth. Similarly, wood blocks immersed in the filtrate became significantly more susceptible to fungal degradation. Pseudomonas sp. from stationary phase growth in crude oil medium depleted residual sugar in basidiomycete-degraded sawdust with a concomitant marked increase in its population. It may be concluded that readily metabolizable products of crude oil degradation by soil organisms and the removal of residual sugar which may have prevented catabolite repression of cellulases, culminated in increased attack on the wood by soil-borne wood-decomposing organisms.     

Biochemistry of microbial polyvinyl alcohol degradation

Effect of minor chemical structures such as 1,2-diol content, ethylene content, tacticity, a degree of polymerization, and a degree of saponification of the main chain on biodegradability of polyvinyl alcohol (PVA) is summarized. Most PVA-degraders are Gram-negative bacteria belonging to the Pseudomonads and Sphingomonads, but Gram-positive bacteria also have PVA-degrading abilities. Several examples show symbiotic degradation of PVA by different mechanisms. Penicillium sp. is the only reported eukaryotic degrader. A vinyl alcohol oligomer-utilizing fungus, Geotrichum fermentans WF9101, has also been reported. Lignolytic fungi have displayed non-specific degradation of PVA. Extensive published studies have established a two-step process for the biodegradation of PVA. Some bacteria excrete extracellular PVA oxidase to yield oxidized PVA, which is partly under spontaneous depolymerization and is further metabolized by the second step enzyme (hydrolase). On the other hand, PVA (whole and depolymerized to some extent) must be taken up into the periplasmic space of some Gram-negative bacteria, where PVA is oxidized by PVA dehydrogenase, coupled to a respiratory chain. The complete pva operon was identified in Sphingopyxis sp. 113P3. Anaerobic biodegradability of PVA has also been suggested.     

Multisubstrate monod kinetic model for simultaneous degradation of chlorophenol mixtures

Chlorophenols (CPs) are persistent and highly toxic compounds rated as priority pollutants by the Environmental Protection Agency (EPA). Frequently, these compounds are present as mixtures of CPs in industrial wastewaters. Therefore the study of biodegradation on mixed pollutants is an important aspect of biodegradation and wastewater treatment. In this work, we studied the multisubstrate degradation of CPs by a mixed culture of Pseudomonas aeruginosa and a novel Acromobacter sp. capable of using pentachlorophenol (PCP), 2,4,6 trichlorophenol (2,4,6 TCP) and 2,3,5,6 tetrachlorophenol (2,3,5,6 TeCP) as the sole sources of carbon and energy. The main objective of this work was to evaluate the effect of substrate mixtures on the degradation kinetics of PCP. Batch experiments were conducted with each CP separately and in mixtures of PCP + 2,4,6 TCP, PCP + 2,3,5,6 TeCP, and PCP + 2,4,6 TCP + 2,3,5,6 TeCP. Based upon our results we have concluded that the simultaneous degradation of CPs is a key factor contributing to the improvement of PCP degradation. The kinetic parameters for PCP and 2,4,6 TCP were obtained by fitting the data to a Monod kinetics model. Using such parameters, the model was able to predict simultaneous multisubstrate degradation of PCP with others CPs.     

Effect of a synthetic surfactant on phenanthrene and n-eicosane utilization by two pure marine strains grown separately in batch cultures with or without sand particles

The effect of Tween 80, a nonionic surfactant, on the extent of biodegradation of phenanthrene by Sphingomonas sp. 2MPII and n-eicosane by Corynebacterium sp. 8 was investigated. This surfactant was beneficial only for phenanthrene biodegradation, where it increased the extent of degradation from 54 to 74%. It appears to be used as carbon source by Corynebacterium sp. 8 but the extent of biodegradation decreases from 43 to 20%. In sand-containing cultures, the phenanthrene sorption observed only in the presence of Tween reduced the biodegradation extent to 35%. On the other hand, for n-eicosane, which remains in the aqueous phase, the biodegradation extent was markedly enhanced to 74%.     

Bioactive compounds in seaweed: functional food applications and legislation

Seaweed is more than the wrap that keeps rice together in sushi. Seaweed biomass is already used for a wide range of other products in food, including stabilising agents. Biorefineries with seaweed as feedstock are attracting worldwide interest and include low-volume, high value-added products and vice versa. Scientific research on bioactive compounds in seaweed usually takes place on just a few species and compounds. This paper reviews worldwide research on bioactive compounds, mainly of nine genera or species of seaweed, which are also available in European temperate Atlantic waters, i.e. Laminaria sp., Fucus sp., Ascophyllum nodosum, Chondrus crispus, Porphyra sp., Ulva sp., Sargassum sp., Gracilaria sp. and Palmaria palmata. In addition, Undaria pinnatifida is included in this review as this is globally one of the most commonly produced, investigated and available species. Fewer examples of other species abundant worldwide have also been included. This review will supply fundamental information for biorefineries in Atlantic Europe using seaweed as feedstock. Preliminary selection of one or several candidate seaweed species will be possible based on the summary tables and previous research described in this review. This applies either to the choice of high value-added bioactive products to be exploited in an available species or to the choice of seaweed species when a bioactive compound is desired. Data are presented in tables with species, effect and test organism (if present) with examples of uses to enhance comparisons. In addition, scientific experiments performed on seaweed used as animal feed are presented, and EU, US and Japanese legislation on functional foods is reviewed.     

Morphological and Molecular Diversity of the Neglected Genus Rhizomastix Alexeieff, 1911 (Amoebozoa: Archamoebae) with Description of Five New Species

The genus Rhizomastix is a poorly known group of amoeboid heterotrophic flagellates living as intestinal commensals of insects, amphibians or reptiles, and as inhabitants of organic freshwater sediments. Eleven Rhizomastix species have been described so far, but DNA sequences from only a single species have been published. Recently, phylogenetic analyses confirmed a previous hypothesis that the genus belongs to the Archamoebae; however, its exact position therein remains unclear. In this study we cultured nine strains of Rhizomastix, both endobiotic and free‐living. According to their light‐microscopic morphology and SSU rRNA and actin gene analyses, the strains represent five species, of which four are newly described here: R. bicoronata sp. nov., R. elongata sp. nov., R. vacuolata sp. nov. and R. varia sp. nov. In addition, R. tipulae sp. nov., living in the intestine of crane flies, is separated from the type species, R. gracilis. We also examined the ultrastructure of R. elongata sp. nov., which revealed that it is more complicated than the previously described R. libera. Our data show that either the endobiotic lifestyle of some Rhizomastix species has arisen independently from other endobiotic archamoebae, or the free‐living members of this genus represent a secondary switch from the endobiotic lifestyle.     

Enhanced remediation of chlorpyrifos by ryegrass (Lolium multiflorum) and a chlorpyrifos degrading bacterial endophyte Mezorhizobium sp. HN3

For effective remediation of contaminants, plant-endophyte partnership is a promising field to be explored. Generally endophytic bacteria assist their host plant by withstanding the stress induced by the contaminants. The objective of this study was to explore the suitability of plant-bacterial partnership for chlorpyrifos (CP) remediation using ryegrass and a CP degrading endophyte, Mesorhizobium sp. HN3 which belongs to plant growth promoting rhizobia. The inoculated yfp-tagged Mesorhizobium sp. HN3 efficiently colonized in the rhizosphere, enhanced plant growth and degradation of CP and its metabolite 3,5,6 trichloro-2-pyridinol (TCP). Significantly lower CP residues were observed in the roots and shoots of plants vegetated in inoculated soil which might be attributed to the efficient root colonization of HN3yfp. These results suggest the involvement of Mesorhizobium sp. HN3yfp in CP degradation inside the roots and rhizosphere of plants and further emphasize on the effectiveness of endophytic bacteria in stimulating the remediation of pesticide contaminants. This is the first report which demonstrates the efficacy of bacterial endophyte for degradation of CP residues taken up by the plant and enhanced remediation of chlorpyrifos contaminated soil.     

Morphological and Molecular Description of Three New Species of the Cyrtophorid Genus Chlamydodon (Ciliophora,Cyrtophoria)

This study investigates the morphology and molecular characteristics of three new cyrtophorid ciliates isolated from China seas: Chlamydodon salinus n. sp., Chlamydodon caudatus n. sp., and Chlamydodon paramnemosyne n. sp. Of these, C. salinus n. sp. differs from its congeners through a combination of body size, a cross‐striated band that is not continuous, the presence of 30–34 somatic kineties, 11–15 nematodesmal rods, and 13 contractile vacuoles. Chlamydodon caudatus n. sp., meanwhile, is characterized by having a conspicuous tail, a continuous cross‐striated band, 34–40 somatic kineties, about 15 contractile vacuoles, and 20–24 nematodesmal rods. Compared with other Chlamydodon species, the third new one, C. paramnemosyne n. sp., could be identified by its continuous cross‐striated band, 16–18 somatic kineties, 5 contractile vacuoles, and 9–12 nematodesmal rods. Based on the sequence of the small subunit (SSU) rRNA gene, the phylogeny of these three new species was analyzed, indicating that they all clustered with other congeners to form a monophyletic assemblage. Based on previous studies and the present work, a brief revision of the genus Chlamydodon is supplied, and a key to aid the identification of Chlamydodon species is given.     

Utilization of immobilized benthic algal species for N and P removal

Laboratory experiments were performed to study the growth rate and phosphorus (P) and nitrogen (N) uptakes of eight benthic microalgae species isolated from different sources of pig manure. Cells immobilized in calcium alginate beads were cultured with three replicates for each species. P removal rates obtained for the unicellular self-aggregating benthic species (Palmellopsis gelatinosa, Chlorosarcinopsis sp., and Macrochloris sp.) were markedly higher than those obtained in previous published experiments. N removal rates were highest for Macrochloris sp., Chlorosarcinopsis sp., and Euglena sp. 2 and comparable to the maximum rates obtained by other authors. Our results show an excellent efficiency of autochthonous benthic species for nutrient removal, especially for P, and call attention to their use for wastewater treatment.     

Revision of the Cales noacki species complex (Hymenoptera,Chalcidoidea, Aphelinidae)

The genus Cales (Hymenoptera: Aphelinidae) includes 13 species worldwide, of which 10 form a highly morphologically uniform species complex with a native range in the Neotropical region. We recognize ten species previously attributed to a single Neotropical species, Cales noacki Howard, which in the strict sense is a species broadly disseminated to control woolly whitefly. A neotype is designated for C. noacki, and it is redescribed based on specimens molecularly determined to be conspecific with the neotype. Newly described species include: C. bicolor Mottern, n.sp ., C. breviclava Mottern, n.sp ., C. brevisensillum Mottern n.sp ., C. curvigladius Mottern, n.sp ., C. longiseta Mottern, n.sp ., C. multisensillum Mottern n.sp ., C. noyesi Mottern, n.sp ., C. parvigladius Mottern, n.sp . and C. rosei Mottern, n.sp . Species are delimited based on a combination of morphological and molecular data (28S‐D2 rDNA and COI). Additional specimens are included in the phylogenetic analyses and although these likely represent several new species, we lack sufficient specimen sampling to describe them at this time. Cales are highly morphologically conserved and character‐poor, resulting in several cryptic species. A molecular phylogeny of the known Neotropical species based on 28S‐D2–5 rDNA and a 390‐bp segment of COI is included, and identification keys to males and females are provided. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:7FEB0479‐9B2E‐48E8‐8603‐4B7C2759D4EC .