Sole Substrate Research Articles

Influence of contaminant exposure on the development of aerobic ETBE biodegradation potential in microbial communities from a gasoline-impacted aquifer

Aerobic biodegradation of ethyl tert butyl ether (ETBE) in a gasoline-impacted aquifer was investigated in laboratory microcosms containing groundwater and aquifer material from ETBE-impacted and non-impacted locations amended with either ETBE, or ETBE plus methyl tert butyl ether (MTBE). As sole substrate, ETBE was biodegraded (maximum rate of 0.54 day−1) without a lag in ETBE-impacted microcosms but with a lag of up to 66 days in non-impacted microcosms (maximum rate of 0.38 day−1). As co-substrate, ETBE was biodegraded preferentially (maximum rate of 0.25 and 0.99 day−1 in non-impacted and impacted microcosms, respectively) before MTBE (maximum rate of 0.24 and 0.36 day−1 in non-impacted and impacted microcosms, respectively). Further addition of ETBE and MTBE reduced lags and increased biodegradation rates. ethB gene copy numbers increased significantly (>100 fold) after exposure to ETBE, while overall cell numbers remained constant, suggesting that ethB-containing microorganisms come to dominate the microbial communities. Deep sequencing of 16S rRNA genes identified members of the Comamonadaceae family that increased in relative abundance upon exposure to ETBE. This study demonstrates the potential for ETBE biodegradation within the unsaturated and saturated zone, and that ETBE biodegrading capability is rapidly developed and maintained within the aquifer microbial community over extended timescales.

Microbial Community Analysis of Anaerobic Enrichment Cultures Supplemented with Bacterial Peptidoglycan as the Sole Substrate.

Methanogenic microbial communities were enriched from rice paddy soil and anaerobic digester sludge using peptidoglycan purified from gram-negative Escherichia coli or gram-positive Micrococcus luteus as the sole substrate. Methane production data suggested the anaerobic degradation of peptidoglycan and also that peptidoglycan from E. coli had lower degradability. The community structures of enrichment cultures fed peptidoglycan from E. coli or M. luteus were similar, but distinctly different. A number of phylogenetically novel and uncultured bacteria, particularly in the phyla Bacteroidetes, WWE1, Armatimonadetes, and Verrucomicrobia, dominated the enrichment cultures, suggesting their involvement in anaerobic peptidoglycan degradation.

Biomethane production using ultrasound pre-treated maize stalks with subsequent microalgae cultivation

This study utilized a renewable energy source, agricultural waste, in anaerobic digestion (AD) at appropriate conditions to obtain biogas and biomethane as an energy carrier. Maize stalks underwent ultrasound (US) pre-treatment for better accessibility for microorganisms, as lignocelluloses have a stable structure, insoluble in water and resist both mechanical and enzymatic attack. The digestate after an anaerobic digestion process was used for cultivation of algae after adsorption with activated carbon for clarification. Photosynthetic microalgae have industrial and economic perspectives, so their low-cost cultivation has a great potential for many applications. The results showed the impact of US pre-treatment of maize stalks as a sole substrate and co-digested with algal biomass. The total yields were 1116 cm3/L, 1350.5 cm3/L and 1293.25 cm3/L for the untreated, ultrasonically pre-treated and microwaved maize stalks. The possibility of accumulating algal biomass using anaerobic digestate as a medium was demonstrated. US pre-treatment (400 W) showed high efficiency with respect to the extractives obtained per unit of energy input. Addition of 4 g/L of microalgal biomass as a co-substrate led to an increase in the biogas yield compared to native stalks. A small closed circle system, starting from anaerobic digestion of lignocellulosic substrates followed by microalgae cultivation in the digestate and subsequent return of microalgal biomass back in the bioreactor as a co-substrate was realized, encouraging circular economy. The suggested scheme is a simple and low-cost technology, as the substrate used is freely available and renewable, and algae proved to grow in a waste effluent as medium.

Targeting CD38-Dependent NAD+ Metabolism to Mitigate Multiple Organ Fibrosis

Synchronous fibrosis in multiple organs is the defining hallmark of systemic sclerosis (SSc), but underlying mechanisms remain poorly understood. Organismal decline in nicotinamide adenine dinucleotide (NAD+), the sole substrate for enzymes critical for cellular metabolism, is implicated in age-related pathologies, and is due to NAD+ consumption catalyzed by CD38. We now show that CD38 is upregulated in SSc skin biopsies, and its levels associate with molecular fibrosis signatures as well as clinical skin fibrosis scores, while key NAD+ -synthesizing enzyme levels are unaltered. Boosting NAD+ via CD38 targeting or by NAD+ precursor supplementation protected older mice from skin and lung fibrosis. Mechanistically, CD38 reduced NAD+ levels and sirtuin activity to augment fibrotic responses, while inhibition of CD38 had the opposite effect. Thus we identify upregulation of CD38 and resulting disrupted NAD+ homeostasis as a fundamental pathogenic mechanism driving fibrosis in SSc, suggesting that CD38 might represent a target for therapy.

Removals of Gentamicin and Benzo[a]Pyrene in an Anaerobic Multichamber Bed Reactor

The petrochemical industry wastewaters were not treated effectively due to high concentrations of Polycyclic aromatic hydrocarbon (PAH) benzo [a] pyren (BaP) and an aminoglucoside antibiotic gentamicin (GNT) in an aerobic treatment plant in Turkey. The high GNT concentration in this industry wastewater mainly originated from the toilets of the working people and from the medical care facilities since an intestinal epidemic occurrred for a period of approximately 1.5 years. The High BaP concentrations release into the wastewater originated from the high BaP production in this industry. In order to improve the biodegradability of petrochemical industry wastewaters containing excess BaP and GNT, different mixtures of BaP and GNT were biodegraded in a high rate anaerobic multichamber bed (AMCBR) reactor. The maximum anaerobic yields for 10 mg/L BaP and 1 mg/ L GNT alone were 45% and 12%, respectively. The addition of primary susbstrate increased the 200 mg/L BaP and 50 mg/ L GNT removals to 97% and 89%, respectively. BaP was biodegraded at short operation times compared to GNT. At low BaP (10-200 mg/ L) and GNT (10-35 mg/ L) concentrations, a non-competitive inhibition does not affect the binding of the substrate and KS were not affected. At high BaP (500-900 mg/ L) and GNT (75-100 mg/ L) concentrations, the BaP and GNT were biodegraded according to competitive inhibition with increased KS. BaP and GNT were biodegraded according to Haldane equations at high concentrations where they were used as the sole substrate.

Tracing the mass flow from glucose and phenylalanine to pinoresinol and its glycosides in Phomopsis sp. XP-8 using stable isotope assisted TOF-MS

Phomopsis sp. XP-8, an endophytic fungus from the bark of Tu-Chung (Eucommia ulmoides Oliv) showed capability to biosynthesize pinoresinol (Pin) and pinoresinol diglucoside (PDG) from glucose (glu) and phenylalanine (Phe). To verify the mass flow in the biosynthesis pathway, [13C6]-labeled glu and [13C6]-labeled Phe were separately fed to the strain as sole substrates and [13C6]-labeled products were detected by ultra-high-performance liquid chromatography-quadrupole time of flight mass spectrometry. As results, [13C6]-labeled Phe was incorporated into [13C6]-cinnamylic acid (Ca) and p-coumaric acid (p-Co), and [13C12]-labeled Pin, which revealed that the Pin benzene ring came from Phe via the phenylpropane pathway. [13C6]-Labeled Ca and p-Co, [13C12]-labeled Pin, [13C18]-labeled pinoresinol monoglucoside (PMG), and [13C18]-labeled PDG products were found when [13C6]-labeled glu was used, demonstrating that the benzene ring and glucoside of PDG originated from glu. It was also determined that PMG was not the direct precursor of PDG in the biosynthetic pathway. The study identified the occurrence of phenylalanine- lignan biosynthesis pathway in fungi at the level of mass flow.

Profiling of Protein Degraders in Cultures of Human Gut Microbiota.

Unabsorbed proteins reach the colon and are fermented by the microbiota, yielding a variety of harmful metabolites. In the present study, a 16S rRNA gene survey identified the bacterial taxa flourishing in 11 batch fermentations with proteins and peptones as the sole fermentable substrates, inoculated with the feces of six healthy adults. Organic acids, ammonia, and indole resulting from protein breakdown and fermentation accumulated in all of the cultures. Analysis of differential abundances among time-points identified Enterobacteriaceae, Burkholderiaceae, and Desulfovibrionaceae (including Esherichia-Shigella, Sutterella, Parasutterella, and Bilophila) among the bacteria that especially in the cultures with low inoculation load. Lachnospiraceae and Ruminococcaceae also encompassed many taxa that significantly expanded, mainly in cultures inoculated with high inoculation load, and showed the strongest correlation with the production of ammonium, indole, and p-cresol. Anaerotruncus, Dorea, Oscillibacter, Eubacterium oxidoreducens, Lachnoclostridium, Paeniclostridium, and Rombutsia were among them. Other Firmicutes (e.g., Roseburia, Ruminococcus, Lachnospira, Dialister, Erysipelotrichaceae, and Streptococcaceae) and many Bacteroidetes (e.g., Barnesiellaceae, Prevotellaceae, and Rickenelliaceae) decreased. Sequences attributed to Bacteroides, unresolved at the level of species, presented opposite contributions, resulting in no significant changes in the genus. This study sheds light on the multitude of bacterial taxa putatively participating in protein catabolism in the colon. Protein fermentation was confirmed as unfavorable to health, due to both the production of toxic metabolites and the blooming of opportunistic pathogens and pro-inflammatory bacteria.

Combined 'moth-eye' structured and graded index-layer anti-reflecting coating for high index glasses.

We present a hybrid antireflective coating (ARC) providing a complete continuous graded refractive index (GRIN) transition from a high-index substrate down to ambient air. The ARC comprises a first GRIN layer of dense silicon-oxy-nitride with a varying, height adjusted material composition. Secondly, a layer of quasi-periodic nanopillars imitating AR-"moth-eye structure" is added to the dense GRIN layer. Demonstrated on a high index glass with a refractive index of ne=1.73 the hybrid GRIN-ARC is applicable to a broad material selection and allows to eliminate any step-like transition up to a refractive index of the substrate of ∼2.0. The ARC offers antireflective properties for large incidence angles and over an extremely broad spectrum ranging from 400 nm up to 2.5 µm. Compared to the sole substrate, the hybrid GRIN-ARC results in an increase of transmittance of more than 10% in the maximum, and more than 6% in the peripheral regions of the spectrum.

Characterisation and microbial community analysis of lipid utilising microorganisms for biogas formation.

In the anaerobic process, fat-oil-grease (FOG) is hydrolysed to long-chain fatty acids (LCFAs) and glycerol (GLYC), which are then used as substrates to produce biogas. The increase in FOG and LCFAs inhibits methanogenesis, and so far, most work investigating this inhibition has been carried out when FOG or LCFAs were used as co-substrates. In the current work, the inhibition of methanogenesis by FOG, LCFAs and GLYC was investigated when used as sole substrates. To gain more insight on the dynamics of this process, the change of microbial community was analysed using 16S rRNA gene amplicon sequencing. The results indicate that, as the concentrations of cooking olive oil (CO, which represents FOG) and LCFAs increase, methanogenesis is inhibited. For instance, at 0.01 g. L-1 of FOG, the rate of biogas formation was around 8 ml.L-1.day-1, and this decreased to <4 ml.L-1.day-1 at 40 g.L-1. Similar results were observed with the use of LCFAs. However, GLYC concentrations up to 100g.L-1 did not affect the rate of biogas formation. Acidic pH, temperature > = 45°C and NaCl > 3% led to a significant decrease in the rate of biogas formation. Microbial community analyses were carried out from samples from 3 different bioreactors (CO, OLEI and GLYC), on day 1, 5 and 15. In each bioreactor, microbial communities were dominated by Proteobacteria, Firmicutes and Bacteroidetes phyla. The most important families were Enterobacteriaceae, Pseudomonadaceae and Shewanellaceae (Proteobacteria phylum), Clostridiacea and Ruminococcaceae (Firmicutes) and Porphyromonadaceae and Bacteroidaceae (Bacteroidetes). In CO bioreactor, Proteobacteria bacteria decreased over time, while those of OLEI and GLYC bioreactors increased. A more pronounced increase in Bacteroidetes and Firmicutes were observed in CO bioreactor. The methanogenic archaea Methanobacteriaceae and Methanocorpusculaceae were identified. This analysis has shown that a set of microbial population is selected as a function of the substrate.

Biodegradation kinetics of dichlorvos and chlorpyrifos by enriched bacterial cultures from an agricultural soil

The study focuses on the biodegradation kinetics of organophosphate pesticides (OPs), chlorpyrifos and dichlorvos by enriched cultures and its application in pesticide transport models. Pseudomonas aeruginosa and Taonella mepensis were the species identified in dichlorvos enriched culture (DEC) while Pseudomonas aeruginosa and Methylobacterium zatmanii were present in chlorpyrifos enriched culture (CPEC). DEC readily degraded dichlorvos as the sole carbon source at higher concentrations up to 1000 mg/L while CPEC rapidly degraded chlorpyrifos up to 100 mg/L. On addition of 1 g/L C of dextrose, dichlorvos degradation efficiency significantly increased only at higher pesticide concentrations while there was no effect on chlorpyrifos degradation. Cross-feed and mixed-feed studies highlighted that, CPEC degraded dichlorvos as a sole substrate and a mixture of both the pesticides effectively when compared to DEC. Edward inhibition and Haldane inhibition models satisfactorily simulated the biodegradation kinetics of dichlorvos and chlorpyrifos by DEC and CPEC respectively. The biokinetic parameters; maximum specific growth rate (µmax), half saturation constant (KC), yield coefficient (Y) and inhibition concentration (Ki) for the selected pesticides were thus estimated from the best fit biokinetic models. Further, batch determined biokinetic parameters were successfully applied to pesticide transport model and used to simulate breakthrough curves (BTCs) from flow-through pesticide soil column studies. The results indicated that the enriched microbes are promising candidates for insitu bioremediation of contaminated waters and soils. In addition, the estimated biokinetic constants can be used to assess the biodegradation capabilities of the enriched cultures and act as input parameters for transport models.

P3476High-resolution respirometry reveals enhanced myocardial mitochondrial ketone oxidation after fasting and ventricular unloading

Abstract Background Impairment of myocardial mitochondrial function is regarded as an established pathomechanism in heart failure. Enhanced oxidation of ketone bodies may potentially exert protective effects on myocardial function. High-resolution respirometry (HRR) resembles a gold-standard methodology to determine myocardial mitochondrial metabolism and oxidative function but has not been validated for ketone substrates yet. Purpose We hypothesized that (1) quantification of ketone body oxidative capacity (OC) in myocardium utilizing ex-vivo HRR is feasible and that (2) ketone-associated OC is elevated after fasting and under conditions of chronic mechanical ventricular unloading. Methods We established new HRR (Oxygraph-2k) protocols, measuring oxygen flux generated by oxidation of the ketone substrates beta-hydroxybutyrate (HBA) and acetoacetate (ACA). Ketone protocols were then applied to twelve C57BL/6 mice' (of which six were fasted for 16h) left ventricular and right liver lobe tissue, as well as to eleven terminal heart failure patients' left ventricular tissue, harvested at heart transplantation. Heart transplant recipients were subdivided into patients with left ventricular assist device prior to transplantation (LVAD group, n=6) or no unloading prior to transplantation (HTX group, n=5). Results In non-fasted rodent hearts, HBA yielded an OC of 25±4 pmol/(s*mg tissue) above basal respiration, when applied as sole substrate (21±11 pmol/(s*mg) in liver). ACA alone did not induce oxygen flux, but ACA+succinate yielded 229% higher oxygen flux than succinate alone in state III (146±32 vs 44±12 pmol/(s*mg); p=0.0003). When titrated after succinate, ACA increased OC by 93±25 pmol/(s*mg) (p=0.0003). In 16h-fasted rodent hearts, HBA-supported OC was 27% higher (41±3 vs 52±9 pmol/(s*mg); p=0.04), while OC with ACA+succinate was unchanged (p=0.60). In rodent liver, no oxygen flux was induced by ACA, reflecting absence of 3-oxoacid CoA-transferase. However, HBA-supported OC was 118% higher in fasted liver (37±13 vs 57±13 pmol/(s*mg); p=0.03). In humans, left ventricular unloading was not associated with altered myocardial OC for fatty acids and glycolytic substrates (standard protocol, p=0.13), but HBA-supported OC was 39% higher in the LVAD group compared to the HTX group (54±12 vs 39±9 pmol/(s*mg), p=0.04). Conclusion Quantification of ketone body OC with HRR is feasible in permeabilized myocardial fibers. Applying this novel method revealed increased HBA-supported myocardial mitochondrial respiration after fasting and chronic left ventricular unloading. These data support a concept of enhanced ketone oxidation following ventricular unloading in myocardial mitochondria. Our findings facilitate new studies on myocardial ketone turnover and the interaction of mitochondrial ketone metabolism with cardiac performance. Acknowledgement/Funding CRC 1116, Research commission of the University Hospital Düsseldorf

Ir-Catalyzed Regiocontrolled Allylic Amination of Di-/Trienyl Allylic Alcohols with Secondary Amines.

An unprecedented regio-controllable allylic amination of unactivated dienyl and trienyl allylic alcohols has been developed, providing an efficient approach toward the site-selective formation of C1-, C3-, and C5-/C7-amination products from the sole substrates. Key to this protocol is the use of secondary amines as the amination reagents, as well as the presence of an iridium catalyst and scandium triflate.

Compatibility of utilising nitrogen-rich oil palm trunk sap for succinic acid fermentation by Actinobacillus succinogenes 130Z

In this study, the potential of oil palm trunk (OPT) sap as a sole substrate for succinic acid (SA) production was evaluated using Actinobacillus succinogenes 130Z. After OPT sap was characterised, the effects of adding carbonate, yeast extract (YE) and minerals to this medium were investigated in an attempt to develop a low-cost fermentation medium. The OPT sap alone, gave comparable SA yield and productivity (0.54 g/g and 0.35 g/L/h) to those supplemented with YE (0.50 g/g and 0.36 g/L/h) and minerals (0.55 g/g and 0.40 g/L/h). The findings showed that OPT sap has sufficient amount of nutrients for SA biosynthesis by A. succinogenes 130Z and could potentially reduce cost without requiring expensive nutrients supplementation.

A novel carbon monoxide fed moving bed biofilm reactor for sulfate rich wastewater treatment

In this study, a moving bed biofilm reactor was used for biodesulfuruization using CO as the sole carbon substrate. The effect of hydraulic retention time (HRT), sulfate loading rate and CO loading rate on sulfate and CO removal was examined. At 72, 48 and 24 h HRT, the sulfate removal was 93.5%, 91.9% and 80.1%, respectively. An increase in the sulfate loading reduced the sulfate reduction efficiency, which, however, was improved by increasing the CO flow rate into the MBBR. Best results in terms of sulfate reduction (>80%) were obtained for low inlet sulfate and high CO loading conditions. The CO utilization was very high at 85% throughout the study, except during the last phase of the continuous bioreactor operation it was around 70%. An artificial neural network based model was successfully developed and optimized to accurately predict the bioreactor performance in terms of both sulfate reduction and CO utilization. Overall, this study showed an excellent potential of the moving bed biofilm bioreactor for efficient sulfate reduction even under high loading conditions.

Improvement in energy recovery from Chlorella sp. biomass by integrated dark-photo biohydrogen production and dark fermentation-anaerobic digestion processes

Chlorella sp. biomass was used as the sole substrate for the production of hydrogen and methane through integrated dark fermentation (DF) and photo-fermentation (PF), and DF and anaerobic digestion (AD) processes. Prior to use in fermentations, the biomass was pretreated by acid-hydrothermal method, which yielded a maximum reducing sugar yield of 162.9 ± 4.2 mg g-biomass−1. The use of the microalgal hydrolysate to produce hydrogen by DF gave a hydrogen yield (HY) of 47.2 ± 1.1 mL g-volatile-solids−1 (VS). The subsequent use of the hydrogenic effluent in PF gave a HY of 125.0 ± 1.5 mL g-VS−1, while AD of the hydrogenic effluent gave a methane yield of 152.8 ± 1.3 mL g-VS−1. The total energy yield attained by the use of DF alone, the integrated DF-PF, and DF-AD processes were 0.51, 1.86 and 5.98 kJ g-VS−1, respectively. These results indicate that the integrated DF-AD process was effective in recovering energy from Chlorella sp. biomass. However, an energy balance analysis indicated that the process was not energetically feasible due to the high energy demand for the acid-hydrothermal pretreatment.

Effect of Substrate on Adult Human Cardiomyocytes Contractility

Prior in vivo studies have reported that the development of heart failure is accompanied by a transition from the normal preferential metabolism of free fatty acids (FFA) to increases in glucose utilization and even ketone bodies, which normally provide a modest contribution to energy balance. However, the functional significance of the altered substrate utilization in the failing heart is poorly understood. Recognizing that nearly all prior studies examining isolated cardiomyocyte physiology have used glucose as the sole metabolic substrate, we initiated studies to examine the impact of alternative metabolic substrates on contractility in isolated human cardiomyocytes. We employed freshly isolated adult human left ventricular cardiomyocytes from non-failing hearts obtained from organ donors (NF, N=11 hearts, N=110 cells) and failing hearts obtained from transplant recipients (HF, N=13 hearts, n=130 cells). Cardiomyocytes were resuspended in a conventional 5mM Glucose Tyrode solution with alternative substrates (Glucose, FFA, R-3-Hydroxybutyrate (3-OHB) or Mix (Glucose + FFA + 3-OHB)). Myocytes were field stimulated at 1 Hz and sarcomere length, fractional shortening, contraction velocity and relaxation velocity were measured using a video-based sarcomere length detection system (IonOptix Corp). Studies using isolated cardiac myocyte contractility as readout confirm that myocytes from NF human hearts are omnivorous: high levels of myocyte fractional shortening (FS) can be achieved under unstressed conditions (1 Hz, unloaded) with any substrate (FSGlucose: 0.132±0.012; FSFFA: 0.143±0.013; FS3OHB: 0.134±0.014; FSMIX: 0.155±0.020). In the failing heart, glucose alone is insufficient to produce normal unstressed myocyte fractional shortening (FSGlucose: 0.088±0.009***, p

Exploitation of Agricultural Waste as Sole Substrate for Production of Bacterial l-Glutaminase Under Submerged Fermentation and the Proficient Application of Fermented Hydrolysate as Growth Promoting Agent for Probiotic Organisms

Microbial l-glutaminase has diverse applications, ranging from food flavouring agent to treatment of cancer. Extracellular l-glutaminase producing one soil bacterium was characterized as Acinetobacter calcoaceticus PJB1 and was grown under submerged fermentation using sugarcane bagasse as sole supporting substrate. The optimum l-glutaminase production was achieved at initial medium pH of 10.0, incubation temperature at 35 °C, inoculums concentration of 1.5% (v/v) and at 72 h. Further improvement of the enzyme production was carried out by statistical optimization procedure using response surface methodology as a result of which enzyme production was enhanced to 47.95 U/ml (2.38-fold improvement). The enzymatic degradation pattern of sugarcane bagasse was appraised using Fourier transform infrared spectroscopy and light microscope. The fermented hydrolysate was proved to be a very effective growth inducer of probiotic organism as reflected by the higher specific growth rate, volumetric growth rate and overall yield of Lactobacillus sp. and Bifidobacterium sp. This study highlights the cost effective production of l-glutaminase and simultaneous utilization of fermented waste product as growth supporting agent for health beneficial probiotic organisms.

Two Different Quinohemoprotein Amine Dehydrogenases Initiate Anaerobic Degradation of Aromatic Amines in Aromatoleum aromaticum EbN1.

Aromatic amines like 2-phenylethylamine (2-PEA) and benzylamine (BAm) have been identified as novel growth substrates of the betaproteobacterium Aromatoleum aromaticum EbN1, which degrades a wide variety of aromatic compounds in the absence of oxygen under denitrifying growth conditions. The catabolic pathway of these amines was identified, starting with their oxidative deamination to the corresponding aldehydes, which are then further degraded via the enzymes of the phenylalanine or benzyl alcohol metabolic pathways. Two different periplasmic quinohemoprotein amine dehydrogenases involved in 2-PEA or BAm metabolism were identified and characterized. Both enzymes consist of three subunits, contain two heme c cofactors in their α-subunits, and exhibit extensive processing of their γ-subunits, generating four intramolecular thioether bonds and a cysteine tryptophylquinone (CTQ) cofactor. One of the enzymes was present in cells grown with 2-PEA or other substrates, showed an α2β2γ2 composition, and had a rather broad substrate spectrum, which included 2-PEA, BAm, tyramine, and 1-butylamine. In contrast, the other enzyme was specifically induced in BAm-grown cells, showing an αβγ composition and activity only with BAm and 2-PEA. Since the former enzyme showed the highest catalytic efficiency with 2-PEA and the latter with BAm, they were designated 2-PEADH and benzylamine dehydrogenase (BAmDH). The catalytic properties and inhibition patterns of 2-PEADH and BAmDH showed considerable differences and were compared to previously characterized quinohemoproteins of the same enzyme family.IMPORTANCE The known substrate spectrum of A. aromaticum EbN1 is expanded toward aromatic amines, which are metabolized as sole substrates coupled to denitrification. The characterization of the two quinohemoprotein isoenzymes involved in degrading either 2-PEA or BAm expands the knowledge of this enzyme family and establishes for the first time that the necessary maturation of their quinoid CTQ cofactors does not require the presence of molecular oxygen. Moreover, the study revealed a highly interesting regulatory phenomenon, suggesting that growth with BAm leads to a complete replacement of 2-PEADH by BAmDH, which has considerably different catalytic and inhibition properties.

The infection of the fruit of ‘Cavendish’ banana by Pseudocercospora fijiensis, cause of black leaf streak (black Sigatoka)

Black leaf streak (black Sigatoka) caused by Pseudocercospora fijiensis (teleomorph Mycosphaerella fijiensis) is the most destructive leaf disease of banana world-wide. It is capable of destroying plantations unless controlled and successful commercial production is dependent on frequent applications of fungicides. A study was made to determine whether the pathogen is capable of infecting the fruit of ‘Cavendish’ banana and completing its life cycle on banana skin as the sole substrate. Emerging and recently emerged bunches of ‘Cavendish’ banana were inoculated in the field with carbendazim-resistant strains of P. fijiensis, incubated in situ in a humid environment for 6 days and then allowed to develop and mature naturally. The fruit were harvested approximately 16 weeks after inoculation, ripened to green tip stage, and skins incubated either as whole skins in humid containers or as thin strips of skin removed from the fruit and incubated on water agar modified with penicillin, streptomycin and carbendazim in Petri dishes. Supradermal fascicles of P. fijiensis were found on the incubated skin strips and whole skins within 5 days. From a total of approximately 300 field inoculated fruit, 18 colonies of P. fijiensis were detected. Small pieces of skin, each supporting a single fascicle, were excised, incubated individually on modified water agar and monitored for the production of conidia. It was shown that the fungus colonised, and was able to sporulate profusely on the excised skin pieces. This finding has implications for the transfer of strains of P. fijiensis between countries via commercial banana shipments and represents a potential pathway of entry to countries currently free of the disease.

The potential application of biosurfactant produced by Pseudomonas aeruginosa TGC01 using crude glycerol on the enzymatic hydrolysis of lignocellulosic material.

The production of biosurfactant by Pseudomonas aeruginosa TGC01 using crude glycerol and sodium nitrate as the sole substrate and nitrogen source, respectively, was investigated using two mineral culture media. Two inoculum sizes (5 and 10% v/v) and two volumes of the culture medium (50 and 100mL) in 500mL Erlenmeyer flask also were used. Enzymatic hydrolyses of waste office paper (WOP), newspaper (NP) and eucalyptus wood chips (EWC) were carried out using the biosurfactant from P. aeruginosa TGC01. The decrease in volume of the culture medium increased the production of rhamnolipid by 500% in relation to concentration obtained when higher volume of culture medium was used. High quantity biosurfactant was recovered (11g/L) with desired surface active properties after extraction using chloroform:methanol (v/v). The biosurfactant was able to reduce the water surface tension from 72 to 27 mN/m with a critical micelle concentration (CMC) of 100mg/L and a stable emulsion index (above 60%) in the enzymatic hydrolysis (pH 4.8 and 50°C for 4h). Biosurfactant increased the glucose released in the enzymatic hydrolysis in relation to control (without tensoactive) when WOP (19% increase) and NP (113% increase) were used. The process for NP (18% lignin) was economical, given that the biosurfactant present made a delignification process unnecessary.