Different Types Of Inoculum Research Articles

Microbial inoculum effects on the rumen epithelial transcriptome and rumen epimural metatranscriptome in calves

Manipulation of the rumen microbial ecosystem in early life may affect ruminal fermentation and enhance the productive performance of dairy cows. The objective of this experiment was to evaluate the effects of dosing three different types of microbial inoculum on the rumen epithelium tissue (RE) transcriptome and the rumen epimural metatranscriptome (REM) in dairy calves. For this objective, 15 Holstein bull calves were enrolled in the study at birth and assigned to three different intraruminal inoculum treatments dosed orally once weekly from three to six weeks of age. The inoculum treatments were prepared from rumen contents collected from rumen fistulated lactating cows and were either autoclaved (control; ARF), processed by differential centrifugation to create the bacterial-enriched inoculum (BE), or through gravimetric separation to create the protozoal-enriched inoculum (PE). Calves were fed 2.5 L/d pasteurized waste milk 3x/d from 0 to 7 weeks of age and texturized starter until euthanasia at 9 weeks of age, when the RE tissues were collected for transcriptome and microbial metatranscriptome analyses, from four randomly selected calves from each treatment. The different types of inoculum altered the RE transcriptome and REM. Compared to ARF, 9 genes were upregulated in the RE of BE and 92 in PE, whereas between BE and PE there were 13 genes upregulated in BE and 114 in PE. Gene ontology analysis identified enriched GO terms in biological process category between PE and ARF, with no enrichment between BE and ARF. The RE functional signature showed different KEGG pathways related to BE and ARF, and no specific KEGG pathway for PE. We observed a lower alpha diversity index for RE microbiome in ARF (observed genera and Chao1 (p < 0.05)). Five microbial genera showed a significant correlation with the changes in host gene expression: Roseburia (25 genes), Entamoeba (two genes); Anaerosinus, Lachnospira, and Succiniclasticum were each related to one gene. sPLS-DA analysis showed that RE microbial communities differ among the treatments, although the taxonomic and functional microbial profiles show different distributions. Co-expression Differential Network Analysis indicated that both BE and PE had an impact on the abundance of KEGG modules related to acyl-CoA synthesis, type VI secretion, and methanogenesis, while PE had a significant impact on KEGGs related to ectoine biosynthesis and D-xylose transport. Our study indicated that artificial dosing with different microbial inocula in early life alters not only the RE transcriptome, but also affects the REM and its functions.

Penambahan Inokulum yang Berbeda pada Ampas Tebu Fermentasi Terhadap Kualitas Nutrisi

Sugarcane bagasse is an agricultural waste that could be processed into ruminant alternative feed. Sugarcane bagasse processing was very necessary to improve the nutritional as animal feed using fermentation application which was one way to increase the nutritional of sugarcane bagasse using cow feces inoculum and EM-4 (Effective Microorganism-4). The purpose of this study was to determine the effect nutritional quality of fermented sugarcane bagasse using different types of inoculum. This study used a Completely Randomized Design (CRD) with 4 treatments and 5 replications that are ; P0: sugarcane bagasse without inoculum addition (control), P1: sugarcane bagasse + 5% cattle feces, P2: sugarcane bagasse + EM-4 10%, P3: sugarcane bagasse + 5% cattle feces + E-4 10%. The parameters measured include dry content, crude protein, crude fiber, and crude fat. The data were analyzed using Analysis of Variance (ANOVA) and continued with Duncan’s Multiple Range Test (DMRT). The results showed that a mixture of 5% cow feces and 10% EM-4 had a very significant effect (P &lt;0.01) to increase crude protein ​​and significantly (P &lt;0.05) to reduce crude fiber. The conclusion of this research was the addition of 5% cow feces inoculum and 10% EM-4 (P3 treatment) was the best treatment because it increased crude protein content and decreased crude fiber

Mycorrhizal mixtures affect the growth, nutrition, and physiological responses of soybean to water deficit

Drought stress has a negative impact on crop growth and productivity worldwide. Plant symbionts such as arbuscular mycorrhizal fungi (AMF) can enhance plant growth and improve plant resistance to drought stress. AMF mixture inocula and plant responses to drought still require further study. The objective of this study was to investigate the effects of non-inoculation (NM) or inoculation with three commercial AMF inocula containing a single or mixtures comprising different numbers of AMF species: M1 (Rhizophagus intraradices), M2 (Rhizophagus clarus, R. intraradices, Septoglomus deserticola, Funneliformis mosseae), and M3 (Rhizophagus intraradices, R. aggregatum, Funneliformis mosseae, Olaroideoglomus etunicatum) on growth, nutritional, and physiological responses of soybean (Glycine max L. cv. Hutcheson) grown in a greenhouse under different water stress levels [WW = well watered (90% FC), MS = medium (60% FC) and SS = severe stressed (30% FC)]. The AMF-inoculated plants had significantly higher plant biomass, chlorophyll content, stomatal conductance, leaf water relations, and mineral contents in comparison to NM plants. Applied mycorrhizal inocula differed in their response to water-deficit conditions. M2 inoculant generally supported greater plant biomass, stomatal conductance, leaf water content, and leaf N, P, K, S, Mn, and Cu contents than M1 and M3 inocula, especially under MS and SS treatments. These results indicated that all mycorrhizal inocula supported plant growth both generally and with soil water deficit; however, M2-inoculated plants performed better than M1 and M3 under drought stress. Therefore, mycorrhizal inocula are effective for supporting soybean growth and offsetting the effects of drought and AMF technology that can support sustainable crop cultivation under soil water-deficit conditions. Different types of inocula have different effects, however, and thus require testing for individual crops.

EVALUATION OF COMBINED TREATMENT OF LEACHATE FROM SANITARY LANDFILL AND SANITARY SEWAGE USING OZONE ON UP FLOW OXIDATION REACTOR

This work aimed at monitoring the formation of aerobic granular sludge in a SBR prototype and at evaluating its performance. The SBR was operated in two different phases (A and B), both fed with real domestic sewage and operated with 6-h cycles, but using different types of inocula: biological sludge from an extended aeration activated sludge system (in Phase A) and biological sludge from a conventional activated sludge system (in Phase B). During This study aimed to evaluate the combined treatment of leachate from landfill and sanitary sewage using ozone on upward flow oxidation reactor. The tests were conducted in batches, taking five and two hours of ozonation with 8.9; 9.6 and 10.5 g O 3 .h -1 , applied to the mixture of 2% of leachate from sanitary landfill and 98% of sanitary sewage (v/v). The test was performed in triplicate with monitoring of COD, BOD, color, turbidity and pH. The results showed that ozone is a viable alternative for the pre-treatment of the mixture containing landfill leachate and sewage, facilitating the post-treatment in a biological process. It was observed removals of COD, BOD, apparent and true color and turbidity of 46%, 51%, 86%, 86% and 81% respectively in 5 hours of test, and average removals of 23%, 48%, 78%, 76% and 58% respectively for 2 hours of test.

Impact of Inoculum Type on the Microbial Community and Power Performance of Urine-Fed Microbial Fuel Cells.

Bacteria are the driving force of the microbial fuel cell (MFC) technology, which benefits from their natural ability to degrade organic matter and generate electricity. The development of an efficient anodic biofilm has a significant impact on the power performance of this technology so it is essential to understand the effects of the inoculum nature on the anodic bacterial diversity and establish its relationship with the power performance of the system. Thus, this work aims at analysing the impact of 3 different types of inoculum: (i) stored urine, (ii) sludge and (iii) effluent from a working MFC, on the microbial community of the anodic biofilm and therefore on the power performance of urine-fed ceramic MFCs. The results showed that MFCs inoculated with sludge outperformed the rest and reached a maximum power output of 40.38 mW·m−2anode (1.21 mW). The power performance of these systems increased over time whereas the power output by MFCs inoculated either with stored urine or effluent decreased after day 30. These results are directly related to the establishment and adaptation of the microbial community on the anode during the assay. Results showed the direct relationship between the bacterial community composition, originating from the different inocula, and power generation within the MFCs.

Enhanced production of propionic acid through acidic hydrolysis by choice of inoculum

AbstractBACKGROUNDIn this study, the enhancement of propionic acid production from a model feedstock mimicking kitchen waste was investigated. For that purpose, two operational runs of a semicontinuous anaerobic hydrolysis reactor were carried out at pH 6.0 ± 0.1 and mesophilic (30 °C) temperature. Two different types of inocula, a mixed microbial culture selected over 24 months for growth on cellulose and a culture contained in goat cheese were compared.RESULTSThe results show that the goat cheese inoculum was significantly more efficient for propionic acid (PA) production. The highest propionic acid concentration achieved amounted to 139 mmol L−1 at a yield of 23.3 mg g−1 volatile solids (VS), which was 55% greater than what was achieved with the mixed culture. Furthermore, it was observed that propionic acid production was enhanced by a combination of high hydraulic retention time (HRT) with low organic loading rate (OLR), ensuring sufficient time for complete processing of the complex organic substrates. The fermentation could be kept in a stable process of propionic acid production at HRT of 20 days and a rather low OLR of 11.1 g L−1 day−1 VS.CONCLUSIONOur results give a better understanding of PA production in semicontinuous mode, applying optimized process parameters and selecting the adequate microbial community for inoculation. This study provides important information for the improvement of PA production from complex substrates for future industrial application. © 2020 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry (SCI).

Obtención de alcohol etílico a partir de dos variedades de cabuya: alternativa para su industrialización

Este proyecto de investigación estudia la utilización de plantas nativas de Furcraea cabuya var. integra y Furcraea cabuya var. cabuya del litoral ecuatoriano, cosechadas en los poblados de: Ayampe, Montecristi, Tosagua, Portoviejo, con el objetivo principal de obtener alcohol etílico mediante la fermentación, destilación y filtración y de esta forma conseguir una bebida alcohólica apta para el consumo humano. En el acondicionamiento y desarrollo experimental se consideran los diferentes parámetros como los diferentes tiempos y temperaturas de cocción, las pruebas con diferentes tipos de inóculos y concentraciones de levaduras, además de diferentes suplementaciones nutritivas (con especial atención a la fuente de nitrógeno). Estableciendo como temperatura óptima para la hidrólisis de la inulina 117 °C durante 4 horas y el proceso fermentativo óptimo utilizando levadura seca activa comercial al 1% p/v con respecto al mosto y una suplementación con sulfato de amonio de 0,15 g/100mL de mosto. El mosto de cabuya rectificado genera una bebida con exquisito sabor a Tequila, la cual luego de ser evaluada sensorialmente demostró que el licor producido se encuentra dentro de los parámetros de aceptación de los consumidores. Palabras clave: etanol, cabuya, destilación, fermentación, mosto, tequila.

Inoculation and habitat amelioration efforts in biological soil crust recovery vary by desert and soil texture

As dryland degradation continues, it is increasingly important to understand how to effectively restore biocrust communities. Potential techniques include the addition of biocrust inoculum to accelerate biocrust recovery. Enhanced erosion typical of degraded environments creates a challenge for these approaches, due to loss by wind or water and burial by saltating particles. To retain and protect added inoculum, the inclusion of habitat‐amelioration techniques can improve recovery rates. This study tested three different types of inoculum (field‐collected, greenhouse‐cultivated, and laboratory‐cultivated biocrust) coupled with two treatments to augment soil stability and ameliorate habitat limitations: soil surface polyacrylamide additions and installation of straw barriers. This was done across two deserts (Great Basin and Chihuahuan) and separated into generally coarse‐ or finer‐textured soils in each desert, with results monitored for 3 years (2015, 2016, 2017). While the inoculum type, coupled with habitat ameliorations, occasionally enhanced biocrust growth across years and treatments, in other cases, it made no difference compared to natural recovery rates. Rather, the desert location and soil texture groupings were the most prominent factors in determining recovery trajectories. Recovery proportions were similar in the finer‐textured sites in both the Great Basin and the Chihuahuan deserts, while the coarser‐textured site in the Great Basin did show some recovery over time and the Chihuahuan coarser‐textured site did not. This study demonstrates the importance of understanding site potential and identifying key limitations to biocrust recovery for successful restoration projects.

Nicotiana attenuata's capacity to interact with arbuscular mycorrhiza alters its competitive ability and elicits major changes in the leaf transcriptome.

To study the local and systemic effects of arbuscular mycorrhizal fungal (AMF) colonization, Nicotiana attenuata plants impaired in their interactions with AMF due to silencing of a calcium- and calmodulin dependent protein kinase (inverted repreat (ir)CCaMK) were grown competitively in pairs with empty vector (EV) plants, with and without two different types of inoculum. When inoculated, EV plants strongly outperformed irCCaMK plants. Foliar transcript profiling revealed that AMF colonization significantly changed gene expression of P-starvation and -transporter genes in irCCaMK plants. The Pht1 family phosphate transporter NaPT5 was not only specifically induced in roots after AMF colonization, but also in leaves of AMF-colonized irCCaMK plants, and in plants grown under low Pi conditions in the absence of AMF. The P-starvation signature of inoculated irCCaMK plants corresponded with increases in selected amino acids and phenolic compounds in leaves. We also found a strong AMF-induced increase in amino acids and phenolic metabolites in roots. Plants impaired in their interactions with AMF clearly have a fitness disadvantage when competing for limited soil nutrients with a fully functional isogenic line. The additional role of the AMF-induced Pht1 family transporter NaPT5 in leaves under P-starvation conditions will require further experiments to fully resolve.

Influence of different sugar sources, nitrogen sources and inocula on the quality characteristics of apple tea wine

An infusion of tea leaves was prepared using 4 g tea/100 mL of the apple juice, ameliorated with different sugar sources, supplemented with different nitrogen sources and inoculated with 5% incola (Saccharomyces cerevisiae var. ellipsoideus, consortia 1 and consortia 2). The highest rate of fermentation and ethanol were found in the apple tea wine having sucrose as a sugar source, while apple juice concentrate as a sugar source gave the highest total phenols, caffeine content and overall acceptability. Higher alcohols, volatile acidity and antioxidant activity were the highest in honey as a sugar source. Apple tea wine having DAHP as a nitrogen source documented the highest ethanol, caffeine content and overall acceptability, lowest higher alcohols, whereas peptone as a nitrogen source had the highest total phenols. Among the different types of inocula, for most of the parameters there were non-significant differences. However, must inoculated with S. cerevisiae var. ellipsoideus for the preparation of apple tea wine resulted in the highest fermentation efficiency, ethanol and overall acceptability but the lowest volatile acidity. Apple tea wine prepared by ameliorating the apple tea must with apple juice concentrate, DAHP and inoculated with S. cerevisiae var. ellipsoideus was rated as the best. Copyright © 2017 The Institute of Brewing & Distilling

BIOMETHANATION OF PINEAPPLE WASTES USING POTENT ANAEROBIC CONSORTIA SUBSTITUTING COW MANURE

The present study deals with the production of biogas from post-harvest wastes of pineapple such as peels, leaves, mixture of peels and leaves with the two different types of inoculum viz., Cow Manure (CM) and Novel microbial Consortia (NC). The results between the two types of inoculum were compared to find out their efficiency. Among the different substrate-inoculum combinations, the biogas production potential was evaluated which resulted that NC was more efficient compared to CM. All assays were conducted till cessation of biogas production which completed on 80th day. Pineapple leaves with NC proven to be best substrate-inoculum combination with maximum biogas yield of 208.28 L/kg Total Solid (TS) comprising of 72.45% methane, whereas same substrate with CM yielded 35.96 L/kg TS with 34.7% methane. Co-digestion mixture of peels and leaves yielded 187.19 l /kg TS with 56.61% methane with NC which was 2.2 fold higher when compared with CM having a yield of

Effect of pH on lactic acid production from acidogenic fermentation of food waste with different types of inocula

Effect of acidic pH (4, 5, 6 and uncontrolled) on lactic acid (LA) fermentation from food waste was investigated by batch fermentation experiments using methanogenic sludge, fresh food waste and anaerobic activated sludge as inocula. Results showed that due to the increase of hydrolysis, substrate degradation rate and enzyme activity, the optimal LA concentration and yield were obtained at pH 5, regardless of the inoculum used. The highest LA concentration (28.4g/L) and yield (0.46g/g-TS) were obtained with fresh food waste as inoculum. Moreover, after the substrate was completely utilized, the lactic acid bacteria population sharply decreased, and the LA produced was converted to volatile fatty acids (VFAs) at pH 6 within a short period. The VFA components varied with the inoculum supplied. Microbial community analysis using high-throughput pyrosequencing revealed that diversity decreased and a high abundance of Lactobacillus (83.4–98.5%) accumulated during fermentation with all inocula.

Influence of the Inoculum Source on the Cariogenicity of in vitro Microcosm Biofilms

This study investigated the cariogenic potential of biofilms originating from different types of inoculum (saliva and dental plaque) from caries-active and caries-free individuals. Ten volunteers were selected from each caries condition for the paired collection of saliva and dental plaque. Microcosm biofilms were grown in triplicate from each inoculum on enamel specimens in 24-well plates under cariogenic challenge. After 10 days, the biofilms were collected for analysis of outcome variables: percentage of surface hardness change (%SHC) and microbiological composition of biofilms. Statistical analysis was performed using the t test, the linear multivariate analysis model and Pearson's correlation coefficients (α = 0.05). A comparative analysis between microbiological baseline data showed higher counts of mutans streptococci in plaque samples within caries-active individuals; a comparative analysis of colony-forming unit (CFU) counts between individuals with different caries status showed higher counts of acid-tolerant microorganisms and mutans streptococci in dental plaque and of acid-tolerant microorganisms in saliva. After 10 days of biofilm growth, the CFU values for total microorganisms, lactobacilli, mutans streptococci and acid-tolerant bacteria, as well as for SHC, were not statistically significant, considering the type of inoculum and caries condition (p > 0.05). A positive correlation was found for %SHC and CFU counts of acid-tolerant bacteria (r = 0.406) and lactobacilli (r = 0.379). Under the limits of this study, the cariogenic potential of biofilms, formed under identical conditions in vitro, is similar, regardless of baseline differences between the source and type of inoculum.

EFFECT OF INOCULUM OF VIABILITY OF NONCULTURABLE CELLS OF BACTERIOCIN-PRODUCING Lactococcus lactis ssp. lactis Strains

The comparative studies on obtaining viable but nonculturable cells (VBNC) of two bacteriocin-producing strains of Lactococcus lactis ssp. lactis of different origins and activity levels under carbohydrate starvation stress have been performed. Two different types of inoculum were applied: P1, unwashed from culture liquid cells, and P2, twice washed with normal 0.9% saline cells. The P1 inoculum shifted to non-culturability faster than P2. During the whole experiment we studied changes in such strain population characteristics as total number of cells, total number of viable cells, number of colony-forming units, number of VBNC (from the nisin-producing activity), and ratio of viable to dead cells in population (using Live/Dead® (Baclight™) staining kit). After 1 year of incubation culturability decreased by 3—6 orders of magnitude in either of populations, and P1 inoculum VBNC demonstrated considerable reduction of cell size. After a year of culturing, the bacteriocin activity of P2 cells was up to 19 times higher than of P1 cells.

Valorisation of biodiesel production wastes: Anaerobic digestion of residual Tetraselmis suecica biomass and co-digestion with glycerol.

One of the principal opportunity areas in the development of the microalgal biodiesel industry is the energy recovery from the solid microalgal biomass residues to optimise the fuel production. This work reports the cumulative methane yields reached from the anaerobic digestion of the solid microalgal biomass residues using different types of inocula, reporting also the improvement of biogas production using the co-digestion of microalgal biomass with glycerol. Results demonstrate that the solid microalgal biomass residues showed better biogas production using a mesophilic inoculum, reaching almost two-fold higher methane production than under thermophilic conditions. Furthermore, the solid microalgal biomass residues methane production rate showed an increase from 173.78 ± 9.57 to 438.46 ± 40.50 mL of methane per gram of volatile solids, when the co-digestion with glycerol was performed. These results are crucial to improve the energy balance of the biodiesel production from Tetraselmis suecica, as well as proposing an alternative way to treat the wastes derived from the microalgae biodiesel production.

Non-culturability and Nisin Production of Lactococcus lactis

We studied formation of non-culturable forms of three bacteriocin (nisin) producing strains of Lactococcus lactis sub sp. lactis: MSU, 729 and F-116 under carbohydrate starvation stress. Two different types of inoculum were applied: A) unwashed cells with culture liquid, B) cells washed twice with normal 0,9%saline. Resulting total numbers of cells were 0.6 1.0×108 cells/ml for both types of inoculum. Population obtained using type A inoculum demonstrated active growth phase within first 1-5 days of incubation (up to 2.4×109 cells/ml) while those obtained using type B inoculum did not grow within that period. Type B population of strain MSU showed phenotypic dissociation that resulted in appearance of micro colonies. After that, we observed active growth phase (up to 5.2×109 cells/ml). Type B cultures of strains 729 and F-116 did not grow during the whole experiment. It was shown that type A population shifted into non-culturability faster than type B. This is due to differences in metabolic strategies and stress sensitivity of these types of population. After 1 year of incubation (383 days) culturability decreased by 3 orders of magnitude for type B (5 orders for type B population of strain MSU) and by 6 orders of magnitude for type A population. We also observed considerable reduction of cell size for type A population of strains 729 and F-116. Studies of bacteriocin activity showed that in type B population cells were up to 78 times more productive compared to those of type A cultures. This phenomenon can be explained by differences in survival strategies of population that use antibacterial potential of bacteriocins for their benefit.

Relative importance of different types of inoculum to the establishment of Mycosphaerella graminicola in wheat crops in north‐west Europe

The contribution of wheat debris to the early stages of septoria leaf blotch epidemics was assessed in a 3‐year field experiment. First lesions were detected very early (December) in the case of an early sowing (mid‐October), showing that the first contamination could occur as soon as the seedlings emerge. The tested debris management options (chopped debris, removal of debris followed by tillage, or tillage in absence of debris) had a strong effect, although transient, on the epidemic dynamic: the more debris present on the soil surface, the more severe initial disease was. The magnitude of differences between treatments differed substantially between years. The relative production of pycnidiospores and ascospores was measured on the chopped debris. Peaks in pycnidiospore and ascospore production coincided in October–November. Both types of spores can be involved as primary inoculum in north‐west European conditions. The local amount of pycnidiospores available on debris in the field, estimated per square metre, was 1000‐fold the local ascospore production. Moreover, inoculum production was quantified on debris exposed to different environmental conditions. Autumnal conditions, characterized by moderate temperature with alternating wet and dry periods, were favourable for the production of both pycnidiospores and ascospores, as shown by the high inoculum production on debris exposed to field or outdoor conditions. By late autumn, the canopy became the most important source of pycnidiospores, and this period, characterized by the decreasing role of debris as a local source of inoculum compared to distant potential sources, can be considered as the end of the early epidemic stages.

Implications of reactor type and conditions on first-order hydrolysis rate assessment of maize silage

The biodegradability and first-order hydrolysis coefficient of maize silage have been assessed from batch experiments using different types of inoculum and substrate to inocula (S/I) ratios, and from CSTRs working at different hydraulic retention times (HRTs). In the batch experiments, the assessed maximum biodegradability of the maize silage was 68 (+/-2.7)% and 73(+/-2.9)% while the first order hydrolysis was 0.26 (+/-0.01) and 0.27(+/-0.02) d(-1), using granular and a mixture of granular and suspended inoculum, respectively. In the CSTR experiment biodegradability ranged from 41-65% depending on the HRT applied whereas the calculated first order hydrolysis coefficient was 0.32 d(-1). It is concluded that batch experiments can be used to assess first order hydrolysis constants and biodegradability provided that a well balanced inoculum is guaranteed. Further, it is shown that CSTR reactors digesting maize silage and operating at HRTs as low as 20 days can attain 88% of maximum biodegradability as long as pH fluctuations are minimized. 2 mmol NaHCO3 per gram maize silage was calculated to suffice for the purpose.

Assessment of the biodegradability of a monosulfonated azo dye and aromatic amines

Biodecolourisation of an azo dye by anaerobic cultures using a liposomal textile levelling agent as primary substrate was assessed. Liposomes seem to facilitate the uptake of the dye (Acid Orange 7) by anaerobic biomass, leading to a fast decolourisation (colour removal of 96% was achieved in the first sample port of the reactor profiles). On the other hand, the presence of dye (60–300 mg l −1) caused a decrease in the chemical oxygen demand (COD) degradation rate (4.1–2.5 g COD removed l −1 d −1 for 60 and 300 mg l −1 of dye, respectively), suggesting inhibitory effects. Aerobic degradation of aromatic amines was investigated in aerobic respirometric assays with different types of inocula. Sulfanilic acid and aniline were mineralised by inocula with a significant microbiological diversity, even with domestic effluent. These results were confirmed by a significant reduction of COD, total organic carbon (TOC) and a high oxygen consumption (biochemical oxygen demand/theoretical oxygen demand), 92±4%. Kinetic analysis showed that a sigmoid function describes quite well the experimental data, even better than the exponential model. Orthanilic and metanilic acids and 1-amino-2-naphtol were persistent under the tested conditions.

Primary biodegradation of ionic liquid cations, identification of degradation products of 1-methyl-3-octylimidazolium chloride and electrochemical wastewater treatment of poorly biodegradable compounds

We investigated the primary biodegradation of different N-imidazoles, imidazolium, pyridinium and 4-(dimethylamino)pyridinium compounds substituted with various alkyl side chains and their analogues containing functional groups principally based on OECD guideline 301 D. For the experiments we used two different types of inocula, a freeze-dried mix of bacteria and activated sludge microorganisms from a wastewater treatment plant. The aim of this study was to improve the knowledge base for the structural design of ionic liquids with respect to an increased biodegradability combined with a reduced (eco)toxicological hazard potential. We found a significant primary biodegradation for (eco)toxicologically unfavourable compounds carrying long alkyl side chains (C6 and C8). In contrast for (eco)toxicologically more recommendable imidazolium ionic liquids with short alkyl (⩽C6) and short functionalised side chains, no biological degradation could be found. The introduction of different functional groups into the side chain moiety thus offering a higher chemical reactivity did not lead to the expected improvement of the biological degradation. After an incubation period of 24 days for the 1-methyl-3-octylimidazolium cation we identified different biological transformation products carrying hydroxyl, carbonyl and carboxyl groups. Furthermore, shortened side chain moieties were identified indicating the degradation of the octyl side chain via β-oxidation. Moreover, we propose an electrochemical wastewater treatment as part of an alternative disposal strategy for non-biodegradable ionic liquids. We show for the first time that the 1-butyl-3-methylimidazolium cation was completely destroyed within four hours using an electrolysis double-cell (volume = 1.2 L) equipped with electrodes made of iridium oxide (anode), stainless steel (cathode), and a boron-doped diamond-coated bipolar electrode. The products formed electrochemically were easily accessible to biological degradation.