Discovery of a cutinase-producing Pseudomonas sp. cohabiting with an apparently nitrogen-fixing Corynebacterium sp. in the phyllosphere

Microorganisms that produce enzymes active on biodegradable polyesters are ubiquitous

Biodegradability standards measure ultimate biodegradation of polymers by exposing the material under test to a natural microbial inoculum. Available tests developed by the International Organization for Standardization (ISO) use inoculums sampled from different environments e.g. soil, marine sediments, seawater. Understanding whether each inoculum is to be considered as microbially unique or not can be relevant for the interpretation of tests results. In this review, we address this question by consideration of the following: (i) the chemical nature of biodegradable plastics (virtually all biodegradable plastics are polyesters) (ii) the diffusion of ester bonds in nature both in simple molecules and in polymers (ubiquitous); (iii) the diffusion of decomposers capable of producing enzymes, called esterases, which accelerate the hydrolysis of esters, including polyesters (ubiquitous); (iv) the evidence showing that synthetic polyesters can be depolymerized by esterases (large and growing); (v) the evidence showing that these esterases are ubiquitous (growing and confirmed by bioinformatics studies). By combining the relevant available facts it can be concluded that if a certain polyester shows ultimate biodegradation when exposed to a natural inoculum, it can be considered biodegradable and need not be retested using other inoculums. Obviously, if the polymer does not show ultimate biodegradation it must be considered recalcitrant, until proven otherwise.

Microbial Turnover and Dispersal Events Occur in Synchrony with Plant Phenology in the Perennial Evergreen Tree Crop Citrus sinensis

Emerging research indicates that plant-associated microbes can alter plant developmental timing. However, it is unclear if host phenology affects microbial community assembly. Microbiome studies in annual or deciduous perennial plants face challenges in separating effects of tissue age from phenological driven effects on the microbiome. In contrast, evergreen perennial trees, like Citrus sinensis, retain leaves for years, allowing for uniform sampling of similarly aged leaves from the same developmental cohort. This aids in separating phenological effects on the microbiome from impacts due to annual leaf maturation/senescence. Here, we used this system to test the hypothesis that host phenology acts as a driver of microbiome composition. Citrus sinensis leaves and roots were sampled during seven phenological stages. Using amplicon-based sequencing, followed by diversity, phylogenetic, differential abundance, and network analyses, we examined changes in bacterial and fungal communities. Host phenological stage is the main determinant of microbiome composition, particularly within the foliar bacteriome. Microbial enrichment/depletion patterns suggest that microbial turnover and dispersal were driving these shifts. Moreover, a subset of community shifts were phylogenetically conserved across bacterial clades, suggesting that inherited traits contribute to microbe-microbe and/or plant-microbe interactions during specific phenophases. Plant phenology influences microbial community composition. These findings enhance understanding of microbiome assembly and identify microbes that potentially influence plant development and reproduction. IMPORTANCE Research at the forefront of plant microbiome studies indicates that plant-associated microbes can alter the timing of plant development (phenology). However, it is unclear if host phenological stage affects microbial community assembly. Microbiome studies in annual or deciduous perennial plants can face difficulty in separating effects of tissue age from phenological driven effects on the microbiome. Evergreen perennial plants, like sweet orange, maintain mature leaves for multiple years, allowing for uniform sampling of similarly aged tissue across host reproductive stages. Using this system, multiyear sampling, and high-throughput sequencing, we identified plant phenology as a major driver of microbiome composition, particularly within the leaf-associated bacterial communities. Distinct changes in microbial patterns suggest that microbial turnover and dispersal are mechanisms driving these community shifts. Additionally, closely related bacteria have similar abundance patterns across plant stages, indicating that inherited microbial traits may influence how bacteria respond to host developmental changes. Overall, this study illustrates that plant phenology does indeed govern microbiome seasonal shifts and identifies microbial candidates that may affect plant reproduction and development.

Cutinase-like biodegradable plastic-degrading enzymes from phylloplane yeasts have cutinase activity

Phylloplane yeast genera Pseudozyma and Cryptococcus secrete biodegradable plastic (BP)-degrading enzymes, termed cutinase-like enzymes (CLEs). Although CLEs contain highly conserved catalytic sites, the whole protein exhibits ≤30% amino acid sequence homology with cutinase. In this study, we analyzed whether CLEs exhibit cutinase activity. Seventeen Cryptococcus magnus strains, which degrade BP at 15 °C, were isolated from leaves and identified the DNA sequence of the CLE in one of the strains. Cutin was prepared from tomato leaves and treated with CLEs from 3 Cryptococcus species (C. magnus, Cryptococcus flavus, and Cryptococcus laurentii) and Pseudozyma antarctia (PaE). A typical cutin monomer, 10,16-dihydroxyhexadecanoic acid, was detected in extracts of the reaction solution via gas chromatography-mass spectrometry, showing that cutin was indeed degraded by CLEs. In addition to the aforementioned monomer, separation analysis via thin-layer chromatography detected high-molecular-weight products resulting from the breakdown of cutin by PaE, indicating that PaE acts as an endo-type enzyme.

Production, purification and application of Cutinase in enzymatic scouring of cotton fabric isolated from Acinetobacter baumannii AU10

Conventional cotton scouring in the textile industry using alkali results in huge environmental impact which can be overcome by using enzymes. Pectinase along with cutinase gives enhanced bioscouring results. Cutin was extracted from tomato peels and was used as substrate in the microbial media. The strain isolated from tomato peel was identified as Acinetobacter baumannii AU10 by 16S rDNA sequencing. The cutinase production was optimized by Placket-Burman and Response Surface Methodology (RSM) and the maximum production of 82.75 U/mL obtained at sucrose 6.68% (w/v), gelatin 2.74 g/L at a temperature of 35.93 °C. Cutinase was purified by ammonium sulfate precipitation, hydrophobic interaction chromatography and ion exchange chromatography with a recovery of 25.6% and specific activity of 38030 U/mg. The confirmation test for the purity of cutinase was analyzed by RP-HPLC. The molecular mass of cutinase was determined as 28.9 kDa by SDS-PAGE technique. Scanning electron microscopic analysis showed a rough and open primary wall surface on the cutinase bioscoured fabric which confirmed its activity on cutin present in the cotton fabric. Additionally, the cutinase-bioscoured samples showed better absorbency than the untreated samples. Therefore, enzymatic scouring increases wetting capacity of scoured cotton and also helps to reduce environmental pollution.

Illumina MiSeq sequencing and network analysis the distribution and co-occurrence of bacterioplankton in Danjiangkou Reservoir, China

Network analysis has contributed to studies of the interactions of microorganisms and the identification of key populations. However, such analysis has rarely been conducted in the study of reservoir bacterioplankton communities. This study investigated the bacterioplankton community composition in the surface water of the Danjiangkou Reservoir using the Illumina MiSeq sequencing platform. We observed that the bacterioplankton community primarily consisted of 27 phyla and 336 genera, including Actinobacteria, Proteobacteria, and Bacteroidetes, demonstrating the richness of the community composition. Redundancy analysis of the bacterioplankton communities and environmental variables showed that the total nitrogen (TN), pH, chemical oxygen demand (COD), and permanganate index (COD_Mn) were important factors affecting the bacterioplankton distribution. Network analysis was performed using the relative abundances of bacterioplankton based on the phylogenetic molecular ecological network (pMEN) method. The connectivity of node i within modules (Zi), the connectivity of node i among modules (Pi), and the number of key bacteria were high at the Taizishan and Heijizui sites, which were associated with higher TN contents than at the other sites. Among the physicochemical properties of water, TN, ammonia nitrogen (NH₄-N), pH, COD, and dissolved oxygen (DO) might have great influences on the functional units of the bacterial communities in bacterioplankton molecular networks. This study improves the understanding of the structure and function of bacterioplankton communities in the Danjiangkou Reservoir.

Interactive effects of Magnaporthe inoculation and nitrogen doses on the plant enzyme machinery and phyllosphere microbiome of resistant and susceptible rice cultivars

Severity of plant diseases is often influenced by the availability of nutrients, particularly N; however, its effect on the phyllosphere microbiome in foliar pathogen challenged plants is less investigated in rice. The tripartite interaction among the fungal pathogen (Magnaporthe oryzae), rice cultivars (basmati and non-basmati, blast resistant or susceptible) and nitrogen (N) fertilization (0, 120 and 180 N) was investigated. Plant growth, elicitation of defense responses and abundance of microbial members in the rice phyllosphere were monitored using biochemical and molecular methods. In general, photosynthetic pigments were distinct for each cultivar, and optimal N doses led to higher values. The susceptible var. CO-39 and resistant CO-39I exhibited higher contents of photosynthetic pigments and micronutrients such as zinc in leaves in response to N doses. Elicitation of defense and hydrolytic enzymes was significantly influenced by pathogen inoculation and modulated by N doses, but varietal effects were distinct. Scoring indices emphasized the pathogen susceptibility of var. CO-39 and PB-1, which showed almost 40-60% higher values than the resistant cultivars; the interactions of cultivars and N doses was also significant. Characteristic changes were recorded in the abundances of the gene copies, particularly, with an overall increase in the number of cyanobacterial 16S rRNA, and bacterial amoA in pathogen-challenged treatments, while nifH gene copies exhibited a reducing trend with increasing N doses, in the presence or absence of pathogen. The varietal differences in the cause and effect relationships can be valuable in crop protection for more effective foliar application of pesticides or biocontrol agents.

Three New Cutinases from the Yeast Arxula adeninivorans That Are Suitable for Biotechnological Applications

The genes ACUT1, ACUT2, and ACUT3, encoding cutinases, were selected from the genomic DNA of Arxula adeninivorans LS3. The alignment of the amino acid sequences of these cutinases with those of other cutinases or cutinase-like enzymes from different fungi showed that they all had a catalytic S-D-H triad with a conserved G-Y-S-Q-G domain. All three genes were overexpressed in A. adeninivorans using the strong constitutive TEF1 promoter. Recombinant 6× His (6h)-tagged cutinase 1 protein (p) from A. adeninivorans LS3 (Acut1-6hp), Acut2-6hp, and Acut3-6hp were produced and purified by immobilized-metal ion affinity chromatography and biochemically characterized using p-nitrophenyl butyrate as the substrate for standard activity tests. All three enzymes from A. adeninivorans were active from pH 4.5 to 6.5 and from 20 to 30°C. They were shown to be unstable under optimal reaction conditions but could be stabilized using organic solvents, such as polyethylene glycol 200 (PEG 200), isopropanol, ethanol, or acetone. PEG 200 (50%, vol/vol) was found to be the best stabilizing agent for all of the cutinases, and acetone greatly increased the half-life and enzyme activity (up to 300% for Acut3-6hp). The substrate spectra for Acut1-6hp, Acut2-6hp, and Acut3-6hp were quite similar, with the highest activity being for short-chain fatty acid esters of p-nitrophenol and glycerol. Additionally, they were found to have polycaprolactone degradation activity and cutinolytic activity against cutin from apple peel. The activity was compared with that of the 6× His-tagged cutinase from Fusarium solani f. sp. pisi (FsCut-6hp), also expressed in A. adeninivorans, as a positive control. A fed-batch cultivation of the best Acut2-6hp-producing strain, A. adeninivorans G1212/YRC102-ACUT2-6H, was performed and showed that very high activities of 1,064 U ml(-1) could be achieved even with a nonoptimized cultivation procedure.

A stress-responsive Escherichia coli protein, CysQ is a highly effective solubility enhancer for aggregation-prone heterologous proteins

When used as an N-terminal fusion expression partner, the Escherichia coli stress-responsive protein, CysQ dramatically increased the cytoplasmic solubility of various aggregation-prone heterologous proteins: Pseudomonas putida cutinase (CUT), human granulocyte colony-stimulating factor (hG-CSF), human ferritin light chain (hFTN-L), arginine deiminase (ADI), human interleukin-2 (IL2), human activation induced cytidine deaminase (AID), and deletion mutant of human glutamate decarboxylase (GAD448-585). As compared with well-known fusion tags such as glutathione-S-transferase (GST) and maltose-binding protein (MBP), the performance of CysQ as solubility enhancer was evidently better than GST and was similar to or better than MBP for the seven heterologous proteins above. This is likely due to the intrinsic ability of CysQ to form its native conformation, probably promoting the binding of molecular chaperones during the folding of CysQ-fusion protein. When used as a substrate, p-nitrophenyl butyrate (PNB) was successfully hydrolyzed to p-nitrophenol by CysQ-CUT fusion mutant. Even after CysQ was removed, the solubility of hFTN-L and hG-CSF, the secondary structure of hG-CSF, and self-assembly activity of hFTN-L were successfully maintained. Conclusively, it seems that CysQ is a highly effective solubility enhancer and fusion expression partner for the production of a variety of bio-active recombinant proteins.

Expression of fungal cutinase and swollenin in tobacco chloroplasts reveals novel enzyme functions and/or substrates

In order to produce low-cost biomass hydrolyzing enzymes, transplastomic lines were generated that expressed cutinase or swollenin within chloroplasts. While swollenin expressing plants were homoplasmic, cutinase transplastomic lines remained heteroplasmic. Both transplastomic lines showed interesting modifications in their phenotype, chloroplast structure, and functions. Ultrastructural analysis of chloroplasts from cutinase- and swollenin-expressing plants did not show typical lens shape and granal stacks. But, their thylakoid membranes showed unique scroll like structures and chloroplast envelope displayed protrusions, stretching into the cytoplasm. Unusual honeycomb structures typically observed in etioplasts were observed in mature chloroplasts expressing swollenin. Treatment of cotton fiber with chloroplast-derived swollenin showed enlarged segments and the intertwined inner fibers were irreversibly unwound and fully opened up due to expansin activity of swollenin, causing disruption of hydrogen bonds in cellulose fibers. Cutinase transplastomic plants showed esterase and lipase activity, while swollenin transplastomic lines lacked such enzyme activities. Higher plants contain two major galactolipids, monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), in their chloroplast thylakoid membranes that play distinct roles in their structural organization. Surprisingly, purified cutinase effectively hydrolyzed DGDG to MGDG, showing alpha galactosidase activity. Such hydrolysis resulted in unstacking of granal thylakoids in chloroplasts and other structural changes. These results demonstrate DGDG as novel substrate and function for cutinase. Both MGDG and DGDG were reduced up to 47.7% and 39.7% in cutinase and 68.5% and 67.5% in swollenin expressing plants. Novel properties and functions of both enzymes reported here for the first time should lead to better understanding and enhanced biomass hydrolysis.

Cutinolytic esterase activity of bacteria isolated from mixed-plant compost and characterization of a cutinase gene fromPseudomonas pseudoalcaligenes

The objective of the current study was to examine cutinolytic esterase (i.e., cutinase) activity by pseudomonads and bacteria isolated from mixed-plant compost. Approximately 400 isolates representing 52 taxa recovered from mixed-plant compost using cuticle baits, along with 117 pseudomonad isolates obtained from a culture collection (i.e., non-compost habitats), were evaluated. The ability of isolates to degrade the synthetic cutin polycaprolactone (PCL) was initially measured. Isolates from 23 taxa recovered from the compost degraded PCL. As well, isolates from 13 taxa of pseudomonads cleared PCL. Secondary screening measured esterase activity induced by the presence of apple cuticle using the chromogenic substrate p-nitrophenyl butyrate. Eighteen isolates representing four taxa ( Alcaligenes faecalis , Bacillus licheniformis , Bacillus pumilus , and Pseudomonas pseudoalcaligenes ) recovered from compost exhibited substantial esterase activity when grown with cuticle. In contrast, none of the pseudomonad isolates from the culture collection produced appreciable esterase activity. Although degradation of PCL was not correlated with esterase activity, isolates that were unable to degrade PCL failed to produce measureable esterase activities. Zymogram analysis indicated that the esterases produced by bacteria from compost ranged in size from 29 to 47 kDa. A gene from P. pseudoalcaligenes (cutA) was found to code for a cutin-induced esterase consisting of 302 amino acids and a theoretical protein size of 32 kDa. The enzyme was unique and was most closely related to other bacterial lipases (≤48% similarity).

The PE-PPE domain in mycobacterium reveals a serine α/β hydrolase fold and function: an in-silico analysis

The PE and PPE proteins first reported in the genome sequence of Mycobacterium tuberculosis strain H37Rv are now identified in all mycobacterial species. The PE-PPE domain (Pfam ID: PF08237) is a 225 amino acid residue conserved region located towards the C-terminus of some PE and PPE proteins and hypothetical proteins. Our in-silico sequence analysis revealed that this domain is present in all Mycobacteria, some Rhodococcus and Nocardia farcinica genomes. This domain comprises a pentapeptide sequence motif GxSxG/S at the N-terminus and conserved amino acid residues Ser, Asp and His that constitute a catalytic triad characteristic of lipase, esterase and cutinase activity. The fold prediction and comparative modeling of the 3-D structure of the PE-PPE domain revealed a "serine α/β hydrolase" structure with a central β-sheet flanked by α-helices on either side. The structure comprises a lid insertion with a closed structure conformation and has a solvent inaccessible active site. The oxyanion hole that stabilizes the negative charge on the tetrahedral intermediate has been identified. Our findings add to the growing list of serine hydrolases in mycobacterium, which are essential for the maintenance of their impermeable cell wall and virulence. These results provide the directions for the design of experiments to establish the function of PE and PPE proteins.

Screening of nonfilamentous bacteria for production of cutin-degrading enzymes

Two hundred thirty-two nonfilamentous bacterial strains, including saprophytes, plant pathogens, and opportunistic plant and human pathogens, were screened for the ability to produce cutinases (cutin-degrading esterases). Initially, esterase activity of culture filtrates of strains grown in nutrient broth-yeast extract medium supplemented with 0.4% apple or tomato cutin was determined by a spectrophotometric assay utilizing the model substrate p-nitrophenyl butyrate. The culture filtrates of the 10 Pseudomonas aeruginosa strains tested exhibited the highest esterase activity, with values of >500 nmol/min/ml. Of these 10 strains, 3 (K799, 1499A, and DAR41352) demonstrated significant induction (10-fold or above) of esterase activity by addition of cutin to nutrient broth-yeast extract medium. The ability of culture filtrates of the three strains to cause release of apple cutin monomers was confirmed by a novel high-performance liquid chromatography technique. Monomer identification was confirmed by gas chromatography-mass spectroscopy analyses. Addition of the nonionic detergent n-octylglucoside stimulated cutinase activity of culture filtrates from strains K799 and DAR41352, but not that of filtrates from strain 1499A. Time course studies in nutrient broth-yeast extract medium supplemented with apple cutin indicated maximal levels of cutinase in the culture fluids after cultures entered stationary phase. Incubation temperatures below the optimal temperature for growth (37 degrees C) led to maximal production of cutinase.

Identification and characterization of bacterial cutinase

Cutinase, which exists in both fungi and bacteria, catalyzes the cleavage of the ester bonds of cutin. Fungal cutinases have been extensively studied, however, reports on bacterial cutinases have been limited due to the lack of knowledge concerning the identity of their open reading frames. In the present study, the cutinase from Thermobifida fusca was induced by cutin and purified to homogeneity by following p-nitrophenyl butyrate hydrolyzing activity. Peptide mass fingerprinting analysis of the wild-type enzyme matched two proteins, Tfu_0883 and Tfu_0882, which are 93% identical in sequence. Both proteins were cloned and overexpressed in their mature form. Recombinant Tfu_0883 and Tfu_0882 display very similar enzymatic properties and were confirmed to be cutinases by their capability to hydrolyze the ester bonds of cutin. Comparative characterization of Fusarium solani pisi and T. fusca cutinases indicated that they have similar substrate specificity and catalytic properties except that the T. fusca enzymes are thermally more stable. Homology modeling revealed that T. fusca cutinases adopt an alpha/beta-hydrolase fold that exhibits both similarities and variations from the fungal cutinase structure. A serine hydrolase catalytic mechanism involving a Ser(170)-His(248)-Asp(216) (Tfu_0883 numbering) catalytic triad was supported by active site-directed inhibition studies and mutational analyses. This is the first report of cutinase encoding genes from bacterial sources.

Screening of tropical fungi producing polyethylene terephthalate-hydrolyzing enzyme for fabric modification

Microfungi were selectively isolated for production of polyethylene terephthalate (PET) fiber-degrading enzymes potentially to be used to modify the surface of polyester fabric. A range of fungi were isolated from plant surfaces and soil samples using a polycaprolactone (PCL) plate-clearing assay technique, and screened for cutinolytic esterase (cutinase) activity. Twenty-two of 115 isolates showed clearing indicating the production of cutinase. The ability of the fungi to produce cutinase in mineral medium (MM) using either potato suberin or PET (1 cm of untreated pre-washed PET fiber) fiber as substrates was assessed based on the hydrolysis of p-nitrophenyl butyrate (p-NPB). All isolates exhibited activity towards p-NPB, isolate PBURU-B5 giving the highest activity with PET fiber as an inducer. PBURU-B5 was identified as Fusarium solani based on its conidial morphology and also nucleotide sequencing from internal transcribed spacer region of the ribosomal RNA gene (rDNA-ITS). Enzymatic modification of PET cloth material properties using crude enzyme from strain PBURU-B5 showed hydrolysis of ester bonds of the PET fiber. The modification of the PET fabric resulted in increase of water and moisture absorption, and general enhancement of hydrophilicity of the fabric, properties that could facilitate processing of fabric ranging from easier dyeing while also yielding a softer feeling fabric for the user.

Production of Fusarium solani f. sp. pisi cutinase in Fusarium venenatum A3/5

Fusarium venenatum A3/5 was transformed using the Aspergillus niger expression plasmid, pIGF, in which the coding sequence for the F. solani f. sp. pisi cutinase gene had been inserted in frame, with a KEX2 cleavage site, with the truncated A. niger glucoamylase gene under control of the A. niger glucoamylase promoter. The transformant produced up to 21 U cutinase l(-1) in minimal medium containing glucose or starch as the primary carbon source. Glucoamylase (165 U l(-1) or 8 mg l(-1)) was also produced. Both the transformant and the parent strain produced cutinase in medium containing cutin.

Enhanced degradation and toxicity reduction of dihexyl phthalate by Fusarium oxysporum f. sp. pisi cutinase

AIMS

This research aims to investigate the efficiency of two lipolytic enzymes--fungal cutinase and yeast esterase--upon the biodegradation of dihexyl phthalate (DHP).

METHOD AND RESULTS

During the enzymatic degradation of DHP dissolved in methanol, several degradation products were detected and their time-course changes were monitored using GC/MS. The DHP-degradation rate of cutinase was surprisingly high; i.e. almost 70% of the initial DHP (500 mg l(-1)) was decomposed within 4.5 h. Although the same amount of esterase was employed, more than 85% of the DHP remained after 3 days. Almost all the DHP was converted by cutinase into 1,3-isobenzofurandione (IBF), whereas hexyl methyl phthalate and IBF were abundantly produced by esterase. In addition, the toxicities of the DHP-degraded products by esterase were evaluated using various recombinant bioluminescent bacteria, which caused oxidative and protein damage, whereas the hydrolysis products from cutinase never caused any cellular damage in the methanol-containing reaction system.

CONCLUSIONS

Cutinase starts to act as a DHP-degrader much earlier and faster than esterase, with high stability in ester-hydrolytic activity, therefore a plausible approach to the practical application of cutinase for DHP degradation in the DHP-contaminated environments may be possible.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study describes the enhanced degradation and detoxification of DHP using Fusarium oxysporum f. sp. pisi cutinase.

Accelerated Degradation of Dipentyl Phthalate by Fusarium oxysporum f. sp. pisi Cutinase and Toxicity Evaluation of Its Degradation Products Using Bioluminescent Bacteria

The efficiency of two lipolytic enzymes (fungal cutinase and yeast esterase) in the degradation of dipentyl phthalate (DPeP) was investigated. The DPeP degradation rate of fungal cutinase was surprisingly high, i.e., almost 60% of the initial DPeP (500 mg/L) was decomposed within 2.5 hours, and nearly 40% of the degraded DPeP disappeared within the initial 15 minutes. With the yeast esterase, despite the same concentration, >87% of the DPeP remained even after 3 days of treatment. The final chemical composition after 3 days was significantly dependent on the enzyme used. During degradation with cutinase, most DPeP was converted into 1,3-isobenzofurandione (IBF) by diester hydrolysis. However, in the degradation by esterase, pentyl methyl phthalate, in addition to IBF, was produced in abundance. Toxicity monitoring using various recombinant bioluminescent bacteria showed that the degradation products from yeast esterase contained a toxic hazard, causing oxidative stress and damage to protein synthesis.

Biodegradation of dipropyl phthalate and toxicity of its degradation products: a comparison of Fusarium oxysporum f. sp. pisi cutinase and Candida cylindracea esterase

The efficiency of two lypolytic enzymes (fungal cutinase, yeast esterase) in the degradation of dipropyl phthalate (DPrP) was investigated. The DPrP-degradation rate of fungal cutinase was surprisingly high, i.e., almost 70% of the initial DPrP (500 mg/l) was decomposed within 2.5 h and nearly 50% of the degraded DPrP disappeared within the initial 15 min. With the yeast esterase, despite the same concentration, more than 90% of the DPrP remained even after 3 days of treatment. During the enzymatic degradation of DPrP, several DPrP-derived compounds were detected and time-course changes in composition were also monitored. The final chemical composition after 3 days was significantly dependent on the enzyme used. During degradation with fungal cutinase, most DPrP was converted into 1,3-isobenzofurandione (IBF) by diester hydrolysis. However, in the degradation by yeast esterase, propyl methyl phthalate (PrMP) was produced in abundance in addition to IBF. The toxic effects of the final degradation products were investigated using various recombinant bioluminescent bacteria. As a result, the degradation products (including PrMP) from yeast esterase severely caused oxidative stress and damage to protein synthesis in bacterial cells, while in the fungal cutinase processes, DPrP was significantly degraded to non-toxic IBF after the extended period (3 days).

Biodegradation and detoxification of organophosphate insecticide, malathion by Fusarium oxysporum f. sp. pisi cutinase

Efficiencies of two lypolytic enzymes (fungal cutinase and yeast esterase) in malathion degradation were investigated. Surprisingly, degradation rate of malathion by fungal cutinase was very high, i.e. almost 60% of initial malathion (500 mg l(-1)) was decomposed within 0.5 h, and nearly 50% of the degraded malathion disappeared within initial 15 min. With the yeast esterase, despite the same concentration, more than 65% of malathion remained even after 2-day treatment. During enzymatic degradation of malathion, two malathion-derived compounds were detected, and time-course changes in composition were also monitored. In the degradation by both fungal cutinase and yeast esterase, two additional organic chemicals were produced from malathion: malathion monoacid (MMA) and malathion diacid (MDA) by ester hydrolysis. Final chemical composition after 2 d was significantly dependent on the enzyme used. Fungal cutinase produced MDA as a major degradation compound. However in the malathion degradation by yeast esterase, an isomer of MMA was produced in abundance in addition to MDA. Toxic effects of malathion and its final degradation products were investigated using various recombinant bioluminescent bacteria. As a result, the degradation products (including MMA) by esterase severely caused membrane damage and inhibition of protein synthesis in bacterial cells, while in the fungal cutinase processes, malathion was significantly degraded to non-toxic MDA after the extended period (2 days).

Investigations on epiphytic living Pseudomonas species from Malus domestica with an antagonistic effect to Venturia inaequalis on isolated plant cuticle membranes

In order to understand better the survival and mutual interaction of epiphytic bacteria and fungi on apple plants, bacteria collected from these plants were cultivated on intact adaxial, stoma free cuticle membranes originally obtained from apple. The bacteria were labelled with luciferase genes from Vibrio harveyi in order to follow up their development and activity on the isolated cuticles. Our finding was that the epiphytic bacteria can have access to nutrients below the cuticle without causing damage to these cuticular membranes. Bacterial proteins may enable this nutrient mobilization and we found, indeed, that more than 46 proteins that must have been delivered by the bacteria in response to interaction with the cuticles as they could be found below the cuticle membrane. Eight major representatives of this group of external proteins have been sequenced with electron spray quadrupole time of flight mass spectrometry and subsequently identified by data base homology search as a flagellin, a porin type protein and proteins that are involved in amino acid recruitment and metabolism.

Enhanced degradation of an endocrine-disrupting chemical, butyl benzyl phthalate, by Fusarium oxysporum f. sp. pisi cutinase

Compared to yeast esterase, fungal cutinase degraded butyl benzyl phthalate (BBP) far more efficiently; i.e., almost 60% of the BBP disappeared within 7.5 h. Also, the final chemical composition significantly depended on the enzyme used. Toxicity monitoring using bioluminescent bacteria showed that butyl methyl phthalate, a major product of degradation by esterase, was an oxidative toxic hazard.

Polyesters in higher plants

Polyesters occur in higher plants as the structural component of the cuticle that covers the aerial parts of plants. This insoluble polymer, called cutin, attached to the epidermal cell walls is composed of interesterified hydroxy and hydroxy epoxy fatty acids. The most common chief monomers are 10,16-dihydroxy C16 acid, 18-hydroxy-9,10 epoxy C18 acid, and 9,10,18-trihydroxy C18 acid. These monomers are produced in the epidermal cells by omega hydroxylation, in-chain hydroxylation, epoxidation catalyzed by P450-type mixed function oxidase, and epoxide hydration. The monomer acyl groups are transferred to hydroxyl groups in the growing polymer at the extracellular location. The other type of polyester found in the plants is suberin, a polymeric material deposited in the cell walls of a layer or two of cells when a plant needs to erect a barrier as a result of physical or biological stress from the environment, or during development. Suberin is composed of aromatic domains derived from cinnamic acid, and aliphatic polyester domains derived from C16 and C18 cellular fatty acids and their elongation products. The polyesters can be hydrolyzed by pancreatic lipase and cutinase, a polyesterase produced by bacteria and fungi. Catalysis by cutinase involves the active serine catalytic triad. The major function of the polyester in plants is as a protective barrier against physical, chemical, and biological factors in the environment, including pathogens. Transcriptional regulation of cutinase gene in fungal pathogens is being elucidated at a molecular level. The polyesters present in agricultural waste may be used to produce high value polymers, and genetic engineering might be used to produce large quantities of such polymers in plants.

Bacteria in the leaf ecosystem with emphasis on Pseudomonas syringae-a pathogen, ice nucleus, and epiphyte

The extremely large number of leaves produced by terrestrial and aquatic plants provide habitats for colonization by a diversity of microorganisms. This review focuses on the bacterial component of leaf microbial communities, with emphasis on Pseudomonas syringae-a species that participates in leaf ecosystems as a pathogen, ice nucleus, and epiphyte. Among the diversity of bacteria that colonize leaves, none has received wider attention than P. syringae, as it gained notoriety for being the first recombinant organism (Ice(-) P. syringae) to be deliberately introduced into the environment. We focus on P. syringae to illustrate the attractiveness and somewhat unique opportunities provided by leaf ecosystems for addressing fundamental questions of microbial population dynamics and mechanisms of plant-bacterium interactions. Leaf ecosystems are dynamic and ephemeral. The physical environment surrounding phyllosphere microbes changes continuously with daily cycles in temperature, radiation, relative humidity, wind velocity, and leaf wetness. Slightly longer-term changes occur as weather systems pass. Seasonal climatic changes impose still a longer cycle. The physical and physiological characteristics of leaves change as they expand, mature, and senesce and as host phenology changes. Many of these factors influence the development of populations of P. syringae upon populations of leaves. P. syringae was first studied for its ability to cause disease on plants. However, disease causation is but one aspect of its life strategy. The bacterium can be found in association with healthy leaves, growing and surviving for many generations on the surfaces of leaves as an epiphyte. A number of genes and traits have been identified that contribute to the fitness of P. syringae in the phyllosphere. While still in their infancy, such research efforts demonstrate that the P. syringae-leaf ecosystem is a particularly attractive system with which to bridge the gap between what is known about the molecular biology of genes linked to pathogenicity and the ecology and epidemiology of associated diseases as they occur in natural settings, the field.

Production of cutinolytic esterase by filamentous bacteria

Thirty-eight strains of filamentous bacteria, many of which are thermophilic or thermotolerant and commonly found in composts and mouldy fodders, were examined for their ability to produce cutinolytic esterase (cutinase) in culture media supplemented with cutin, suberin or cutin-containing agricultural by-products. Initially, the ability of culture supernatants to hydrolyse the artificial substrate p-nitrophenyl butyrate was determined by spectrophotometric assays. Only one bacterium, Thermoactinomyces vulgaris NRRL B-16117, exhibited cutinolytic esterase production. The enzyme was highly inducible, was repressed by the presence of glucose in the medium and hydrolysed both apple and tomato cutins. Inducers included apple cutin, apple pomace, tomato peel, potato suberin and commercial cork. Unlike similar fungal enzymes, the T. vulgaris cutinolytic esterase was not inducible by cutin hydrolysate. The cutinolytic esterase exhibited a half-life of over 60 min at 70 degrees C and a pH optimum of >/= 11.0. This study indicates that thermophylic filamentous bacteria may be excellent commercial sources of heat-stable cutin-degrading enzymes that can be produced by fermentation of low cost feedstocks.

Cutinase: from molecular level to bioprocess development

This review analyzes the role of cutinases in nature and their potential biotechnological applications. The cloning and expression of a fungal cutinase, Fusarium solani f. pisi, in Escherichia coli and Saccharomyces cerevisiae hosts are described. The three-dimensional structure of this cutinase is also analyzed and its function as a lipase is discussed and compared with other lipases. The biocatalytic applications of cutinase are described taking into account the preparation of different cutinase forms and the media in which the different types of reactions have been performed, namely hydrolysis, esterification, transesterification, and resolution of racemic mixtures. The stability of cutinase preparations is discussed and, in particular, the cutinase stability in anionic reversed micelles is analyzed considering the role of hexanol as a substrate, a cosurfactant, and a stabilizer. Process development, based on the operation of cutinase reactors, is also reviewed.

Purification and characterization of cutinase from a fluorescent Pseudomonas putida bacterial strain isolated from phyllosphere

Cutinase, an extracellular enzyme, was induced by cutin in a fluorescent Pseudomonas putida strain that was found to be cohabiting with an apparently nitrogen-fixing Corynebacterium. This enzyme was purified from the culture fluid by acetone precipitation followed by chromatography on DEAE-cellulose, QAE-Sephadex, Sepharose 6B, and Sephadex G-100. The purified enzyme showed a single band when subjected to polyacrylamide electrophoresis and the enzymatic activity coincided with the protein band. Sodium dodecyl sulfate-polyacrylamide electrophoresis showed a single band at a molecular weight of 30,000 and gel filtration of the native enzyme through a calibrated Sephadex G-100 column indicated a molecular weight of 30,000, showing that the enzyme is a monomer. The amino acid composition of bacterial cutinase is distinctly different from that of fungal or plant cutinases. This bacterial cutinase showed a broad pH optimum between 8.5 and 10.5 with 3H-labeled apple cutin as the substrate. Linear rates of cutin hydrolysis were measured up to 20 min of incubation time and 4 mg/ml of cutin gave the maximum hydrolysis rate. This cutinase catalyzed hydrolysis of p-nitrophenyl esters of C4 to C16 fatty acids with decreasing V and increasing Km for the longer chain esters. It did not hydrolyze tripalmitoyl glycerol or trioleyl glycerol, indicating that this is not a general lipase. Active serine-directed reagents such as organophosphates and organoboronic acids severely inhibited the enzyme, suggesting that bacterial cutinase is an "active serine" enzyme. Neither thiol-directed reagents nor metal ion chelators had any effect on this enzyme. Antibody raised against purified enzyme gave a single precipitin line on Ouchterlony double diffusion analysis. Western blot analysis of the extracellular fluid of induced Ps. putida showed a single band at 30 kDa. No immunological cross-reactivity was detected between the present bacterial enzyme and the fungal enzyme from Fusarium solani pisi when rabbit antibodies against either enzyme was used.