The microbial oxidation of (-)-beta-pinene by Botrytis cinerea

(-)-beta-pinene, a flavor and fragrance monoterpene is an important constituent of essential oils of many aromatic plants. It was oxidized by a plant-pathogenic fungus, Botrytis cinerea to afford four metabolites characterized as (-)-6a-hydroxy-beta-pinene, (-)-4beta,5beta-dihydroxy-beta-pinene, (-)-2beta,3beta-dihydroxypinane, and (-)-4beta-hydroxy-beta-pinene-6-one by detailed spectroscopic studies along with other known metabolites.     

Biotransformation of two cytotoxic terpenes, alpha-santonin and sclareol by Botrytis cinerea

Two cytotoxic terpenes, alpha-santonin (1) and sclareol (3) were biotransformed by a plant pathogenic fungus Botrytis cinerea to produce oxidized metabolites in high yields. Alpha-Santonin (1) on fermentation with the fungus for ten days afforded a hydroxylated metabolite identified as 11beta-hydroxy-alpha-santonin (2) in a high yield (83%), while sclareol (3) was metabolized to epoxysclareol (4) (64%) and a new compound 8-deoxy-14,15-dihydro-15-chloro-14-hydroxy-8,9-dehydrosclareol (5) (7%), representing a rare example of microbial halogenation.     

Oxidation of Alcohols by Botrytis cinerea

Crude cell-free preparations of Botrytis cinerea were found to oxidize straight-chain primary alcohols (except methanol), aromatic primary alcohols, and unsaturated primary alcohols. The resulting products were the corresponding aldehydes and an equal molar quantity of hydrogen peroxide.     

Bioconversion of alpha-Damascone by Botrytis cinerea

Bioconversion of alpha-damascone (compound 1) was studied with four strains of Botrytis cinerea in grape must (pH 3.2). As biotransformation products of compound 1, 3-oxo-alpha-damascone, cis- and trans-3-hydroxy-alpha-damascone, gamma-damascenone, 3-oxo-8, 9-dihydro-alpha-damascone, and cis- and trans-3-hydroxy-8,9-dihydro-alpha-damascone were identified. In addition, acid-catalyzed chemical transformation of compound 1 to the diastereomers of 9-hydroxy-8,9-dihydro-alpha-damascone was observed. Identifications were performed by capillary gas chromatography (HRGC) and coupled HRGC techniques, i.e., on-line HRGC-mass spectrometry and HRGC-Fourier transform infrared spectroscopy, after extractive sample preparation.     

Bioconversion of citronellol by Botrytis cinerea

Summary Bioconversion of citronellol 1 was studied with four strains of Botrytis cinerea. Using grape must predominant transformation of 1 to 2,6-dimethyl-1,8-octandiol 2 and (E)-2,6-dimethyl-2-octen-1,8-diol 3 was observed. In minor amounts 2,6-dimethyl-2,8-octandiol 4, two p-menthan-3,8-diol isomers 5a, 5b, (Z)-2,6-dimethyl-2-octen-1,8-diol 6, isopulegol 7, 2-methyl-2-hepten-6-one-1-ol 8 and 2-methyl--butyrolactone 9 were found. Using a small amount of grape must in a synthetic medium (1:700) the bioconversion products 2, 4, 5a and 5b were absent, but additionally 2-methyl-2-hepten-6-one 10, 2-methyl-2-hepten-6-ol 11 and citronellic acid 12 were detected. The results obtained were strongly dependent on the strains used; one strain did not show any metabolic activity against 1. The bioconversion products were identified by capillary gas chromatography (HRGC) and coupled HRGC techniques, i.e. on-line — mass spectrometry (HRGC-MS) and — Fourier transform infrared spectroscopy (HRGC-FTIR).     

Degradation of Extracellular beta-(1,3)(1,6)-d-Glucan by Botrytis cinerea

During growth on glucose, Botrytis cinerea produced extracellular beta-(1,3)(1,6)-d-glucan (cinerean), which formed an adhering capsule and slime. After glucose was exhausted from the medium, cinereanase activity increased from <0.4 to 30 U/liter, effecting a striking loss in the viscosity of the culture. Cinerean was cleaved into glucose and gentiobiose. Gentiobiose was then hydrolyzed to glucose. While cinereanase activity was strongest in the culture supernatant, gentiobiase activity was located mainly in the cell wall fraction. The addition of extra glucose or cycloheximide prevented the cinerean degradation caused by an effect on cinereanase formation. Cinerean degradation was accompanied by microconidiation and sclerotium formation. B. cinerea was found to grow on cinerean with the latter as its single carbon and energy source. In this case, cinerean degradation occurred during hyphal growth, and no microconidiation or sclerotium formation was observed. Growth experiments with various carbon sources indicated that cinerean had a positive effect on the formation of cinerean-degrading enzymes.     

Microbial Production of Abscisic Acid by Botrytis cinerea

The effect of oryzalexin D, which has been isolated as a group of novel phytoalexins of rice plant, on DNA, RNA, protein, lipid and chitin biosyntheses, respiration and cell membrane permeability was investigated in Pyricularia oryzae. The concentration for 50% inhibition (ED₅₀) by oryzalexin D of the mycelial growth of P. oryzae was 230 ppm. At this concentration, oryzalexin D inhibited equally the incorporation of [2–¹⁴C]thymidine, [2–¹⁴C]uridine, l-[U-¹⁴C]amino acid mixture, l-[methyl-¹⁴C]methionine and d-[l-¹⁴C]glucosamine into DNA, RNA, protein, lipid and chitin in intact cells, but did not inhibit these systems in a homogenate of the mycelia of P. oryzae. Oryzalexin D scarcely inhibited the respiration of the homogenate and mitochondria at ED₅₀. On the other hand, oryzalexin D at ED₅₀ caused leakage of potassium and inhibited the uptake of glutamate by mycelial cells of P. oryzae. These results suggest that interference with the cell membrane function is responsible for the primary mode of action.of oryzalexin D against P. oryzae.     

Detection of Botrytis cinerea by loop-mediated isothermal amplification

Aims: To develop a sensitive, rapid and simple method for detection of Botrytis cinerea based on loop‐mediated isothermal amplification (LAMP) that would be suitable for use outside a conventional laboratory setting. Methods and Results: A LAMP assay was designed based on the intergenic spacer of the B. cinerea nuclear ribosomal DNA (rDNA). The resulting assay was characterized in terms of sensitivity and specificity using DNA extracted from cultures. The assay consistently amplified 65 pg B. cinerea DNA. No cross‐reactivity was observed with a range of other fungal pathogens, with the exception of the closely related species Botrytis pelargonii. Use of a novel real‐time LAMP platform (the OptiGene Genie I) allowed detection of B. cinerea in infected rose petals, with amplification occurring in <15 min. Conclusions: The LAMP assay that was developed is suitable for rapid detection of B. cinerea in infected plant material. Significance and Impact of the Study: The LAMP method combines the sensitivity and specificity of nucleic acid‐based methods with simplified equipment and a reduced reaction time. These features make the method potentially suitable for on‐site use, where the results of testing could help to inform decisions regarding the storage and processing of commodities affected by B. cinerea, such as cut flowers, fruit and vegetables.     

Biotransformation of (-)-verbenone by human liver microsomes

The biotransformation of (-)-verbenone was investigated with human liver microsomes by using GC-MS. Regioselective biotransformation was observed when (-)-verbenone was incubated with the liver microsomes. (-)-10-Hydroxyverbenone was formed from (-)-verbenone of kinetic analysis showed that the Km and Vmax values for the hydroxylation of (-)-verbenone by liver microsomes from three human samples, HG-70, HG-56 and HG-23, were 1.1 mM and 4.8 nmol/min/nmol P450, 0.6 mM and 2.1 nmol/min/nmol P450, and 2.8 mM and 4.6 nmol/min/nmol P450, respectively.     

The Botrytis cinerea early secretome

The extracellular proteome, or secretome, of phytopathogenic fungi is presumed to be a key element of their infection strategy. Especially interesting constituents of this set are those proteins secreted at the beginning of the infection, during the germination of conidia on the plant surfaces or wounds, since they may play essential roles in the establishment of a successful infection. We have germinated Botrytis cinerea conidia in conditions that resemble the plant environment, a synthetic medium enriched with low molecular weight plant compounds, and we have collected the proteins secreted during the first 16 h by a double precipitation protocol. 2‐D electrophoresis of the precipitated secretome showed a spot pattern similar for all conditions evaluated and for the control medium without plant extract. The proteins in 16 of these spots were identified by PMF and corresponded to 11 different polypeptides. Alternative determination of secretome composition by LC‐MS/MS of tryptic fragments rendered a much larger number, 105 proteins, which included all previously identified by PMF. All proteins were functionally classified according to their putative function in the infection process. Key features of the early secretome include a large number of proteases, the abundance of proteins involved in the degradation of plant defensive barriers, and plenty of proteins with unknown function.     

Biotransformation of (-)-menthone by human liver microsomes

The aim of the current study was to investigate the metabolism of (-)-menthone by liver microsomes of humans. (-)-Menthone (1) was metabolized to (+)-neomenthol (2) (3-reduction) and 7-hydroxymenthone (3) by human liver microsomes. The metabolites formed were analyzed on GC and GC-MS. Kinetic analysis showed that K(m) and V(max) values for the metabolized (-)-menthone to respective (+)-neomenthol and 7-hydroxymenthone by liver microsomes of human sample HG70 were 0.37 mM and 4.91 nmol/min/mg protein and 0.07 mM and 0.71 nmol/min/mg protein.     

Oxidative metabolism of ambrox and sclareolide by Botrytis cinerea

Ambrox (1), a perfumery diterpene, was oxidatively metabolised by a plant pathogenic fungus Botrytis cinerea in a xenobiotic fashion to afford a major product, i.e., 1beta-hydroxy-8-epiambrox (13) (60%) along with three minor metabolites 3beta-hydroxyambrox (2), sclareolide (5) and 3beta-hydroxysclareolide (7). Sclareolide (5), a cytotoxic diterpenoidal lactone was fermented with the same fungus to yield 3beta-hydroxysclareolide (7) (59%) as a major metabolite together with two minor metabolites characterised as 1-ketosclareolide (15), and 3beta,14-dihydroxysclareolide (16).     

Microbial transformation of geraniol and nerol by Botrytis cinerea

Summary Biotransformation of geraniol 1A and nerol 1B was studied with four strains of Botrytis cinerea and three growth media. Using grape must predominant conversion of 1A/1B to E-3,7-dimethyl-2-octen-1,8-diol 5 and 2Z,6E-3,7-dimethyl-2,6-octadien-1,8-diol 16B was observed. However, with one strain and 1A, E-2-methyl-2-hepten-6-one-1-ol 2B, 7-hydroxy-6-methyl-2-heptanone 3 and p-menth-1-ene-9-ol 7 were identified as major metabolites. As further fungal bioconversion products of 1A/1B were detected: Z-2-methyl-2-hepten-6-one-1-ol 2A, 2E,6Z-, 2E,6E-and 2Z,6Z-3,7-dimethyl-2,6-octadien-1,8-diol 4A/4B/16A, Z-3,7-dimethyl-2-octen-1,8-diol 17, 3,7-dimethyl-1,8-octandiol 6, 2E,6E-8-hydroxy-2,6-dimethyl-2,6-octadienal 8, geranial and neral 9, 18, citronellol 10, Z- and E-2,6-dimethyl-2,7-octadien-1,6-diol 13A/13B, 6-hydroxy-2,6-dimethyl-2,7-octadienal 14 as well as 2,6-dimethyl-7-octen-1,6-diol 15. Using synthetic growth medium again -hydroxylation reactions were observed, but 2-methyl-2-hepten-6-one 11 and 7 were also identified as major bioconversion products of 1A and 1B, respectively. Additionally, 2-methyl-2-hepten-6-ol 12 was detected and, using 1B, also traces of 2Z,6E-8-hydroxy-2,6-dimethyl-2,6-octadienal 19 and two 3,9-epoxy-p-menth-1-ene isomers 20A/20B were found. Addition of small amounts of grape must to the synthetic medium (1:700 to 5:700) influenced both the yields of metabolites and their qualitative and quantitative distribution. Identifications of biotransformation products of 1A/1B were performed by capillary gas chromatography (HRGC) and coupled HRGC techniques, i.2. on-line-mass spectrometry (HRGC-MS) and-Fourier transform infrared spectroscopy (HRGC-FTIR) after extractive sample preparation.