Enzyme Activities and Chemical Changes in Wet Olive Cake after Treatment with Pleurotus ostreatus or Eisenia fetida

A laboratory experiment was conducted to evaluate the enzyme activities and chemical changes recorded in a recalcitrant phenolic-rich waste after treatment with Pleurotus ostreatus or Eisenia fetida. The waste used was wet olive cake (alperujo in Spanish), a waste produced in huge amounts by the olive oil industry. Both P. ostreatus and E. fetida were very effective in removing phenolic compounds, the initial concentration in the wet olive cake being reduced in both cases by around 90%. Laccase and manganese peroxidase activities were measured in the growth medium of P. ostreatus, and catechol 2,3 dioxygenase activity was only detected in the waste treated with Eisenia; these could be the main factors responsible for the oxidation of phenolic compounds. Increases of dehydrogenase and β-glucosidase activities were detected in the degraded wet olive cake by fungi or earthworms. In comparison with the natural wet olive cake, the degraded products had lower total organic carbon and humic acid contents but were rich in nitrogen and other nutrients, having lower C:N ratios. In addition, the toxicity of the wet olive cake against the seeds of Lepidium sativum significantly decreased after degradation. The low toxicity as well as moderate stability and maturity recorded in the wet olive cake treated with P. ostreatus or E. fetida imply that these products could be used as soil amendments.     

Liquid chromatography–mass spectrometry and gas chromatography–mass spectrometry of ω- and (ω-1)-hydroxylated metabolites of elaidic and oleic acids in human and rat liver microsomes

In order to characterize the nature of the active site of cytochrome P450 2E1, the metabolism of various fatty acids with cis/trans geometric configurations has been investigated. A system coupling atmospheric pressure chemical ionization-mass spectrometry detection with HPLC separation was developed as an alternative method for the characterization of hydroxylated metabolites of oleic and elaidic acids in rat and human liver microsomes. Oxidation of oleic and elaidic acids led to the formation of two main metabolites which were identified by LC–MS and GC–MS as ω and (ω-1)-hydroxylated (or 17-OH and 18-OH) fatty acids, on the basis of their pseudo-molecular mass and their fragmentation. The assay was accurate and reproducible, with a detection limit of 25 ng per injection, a linear range from 25 to 1128 ng per injection, no recorded interference, intra-day and inter-day precision with variation coefficients <14%. This LC–MS method was validated with oleic acid by using both radiometric and mass spectrometric detections. A significant correlation was found between the two methods in human (r=0.86 and 0.94 with P<0.05 and 0.01) and rat liver microsomes (r =0.90 and 0.85 with P<0.01 and 0.05) for 17-OH and 18-OH metabolites, respectively. HPLC coupled to mass spectrometry for the analysis of hydroxylated metabolites of elaidic acid offers considerable advantages since the method does not require use of a radioactive molecule, completely separates the two hydroxymetabolites, confirms the identification of each metabolite, and is as sensitive as the radiometric analysis method. This method allowed the comparative study of oleic and elaidic acid hydroxylations by both human and rat liver microsomal preparations.     

Lipogenesis in the Basidiomycetes Pleurotus ostreatusand Flammulina velutipes Cultivated on Different Media

The compositions of free fatty acids (FA) in the mycelia of oyster cap (Pleurotus ostreatus (Jacq. ex Fr.) Kumm.) and honey mushroom (Flammulina velutipes (Curt. ex Fr.) Sing.) and the effect of mycelium cultivation conditions on the composition and proportions of individual FA were investigated. Palmitic and linoleic acids were found to be major acids produced byP. ostreatus growing on solid agar medium and in a submerged culture with a synthetic medium. The composition of minor FA in P. ostreatuswas dependent on cultivation conditions. Surface cultivation of its mycelium yielded pentadecanoic, octadecenoic, and stearic acids. Submerged cultivation additionally yielded undecanoic, myristic, hexadecenoic, and lignoceric acids. The composition of free FA in F. velutipesshowed no significant differences from that of P. ostreatus. Variation in the C/N ratio in the cultivation medium affected both the FA composition in P. ostreatus and F. velutipes and the relationship between saturated and unsaturated FA.     

Optimization of rice bran and food waste compost contents in mushroom culture medium to maximize mycelial growth rate and fruit body yield of Pleurotus ostreatus

The objective of this study was to find optimum rice bran (RB) and food waste compost (FWC) contents in culture medium for mycelial growth rate and fruit body yield of oyster mushroom, Pleurotus ostreatus. RB (0–20%) and FWC (20–40%) contents significantly affected the fruit body yield of P. ostreatus. Within the design boundaries, the optimum conditions for maximum mycelial growth rate (14.8 cm 20 d⁻¹) were 9.3% RB and 24% FWC. The optimum conditions for maximum fruit body yield (91 g bottle⁻¹) were 12% RB and 25% FWC, which was 153% higher than value (36 ± 11 g bottle⁻¹) at the control condition of 80% w/w sawdust and 20% w/w RB. Our results proved a good potential of FWC to serve as an alternative growth medium for cultivating oyster mushroom, P. ostreatus. This may improve the production efficiency of edible mushrooms to help minimize production costs and maximize farm profits.     

Bioconversion of agricultural lignocellulosic wastes through the cultivation of the edible mushrooms Agrocybe aegerita,Volvariella volvacea and Pleurotus spp.

Ten selected wild and commercial strains of Pleurotus ostreatus,Pleurotus eryngii,Pleurotus pulmonarius, Agrocybe aegerita andVolvariella volvacea were cultivated on three agricultural wastes, i.e. wheat straw (WS), cotton waste (CW) and peanut shells (PS). All species demonstrated significantly higher colonization rates on WS and CW than on PS. WS supported faster growth of A. aegerita and Pleurotus spp., whereas V. volvacea performed better on CW. Comparison of growth rates on composted and non-composted WS and CW substrates revealed that in the latter case faster colonization was achieved, particularly for Pleurotus spp. However, one commercial strain of V. volvacea presented higher growth rates when the composted CW medium was used. Furthermore, earliness in the fructification of P. ostreatus, P. pulmonarius and V. volvacea strains was promoted in CW substrates, while WS favoured earliness of P. eryngii and A. aegerita. Similarly, high sporophore yields were obtained by P. ostreatus and P. pulmonarius on both wastes, whereas WS enhanced yield and basidioma size of P. eryngii and A. aegerita strains and CW production of V. volvacea. The substrates cellulose:lignin ratios were found to be positively correlated to mycelial growth rates and to mushroom yield of P. ostreatus and P. pulmonarius; in addition, positive correlation was also detected for carbon:nitrogen ratio and mushroom yield in P. eryngii and A. aegerita and between cellulose content and mushroom yield for V. volvacea strains.     

Lipophilic Metabolites from Five‐Needle Pines,Pinus armandii and Pinus kwangtungensis,Exhibiting Antibacterial Activity

Lipophilic extractive metabolites from needles and defoliated twigs of Pinus armandii and P. kwangtungensis were studied by GC/MS. Needles of P. armandii contained predominantly 15‐O‐functionalized labdane type acids (anticopalic acid), fatty acids, nonacosan‐10‐ol, sterols, nonacosan‐10‐ol and sterol saponifiable esters, and acylglycerols, while P. kwangtungensis needles contained no anticopalic acid, but more trinorlabdane (14,15,16‐trinor‐8(17)‐labdene‐13,19‐dioic acid) and other labdane type acids, nonacosan‐10‐ol and its saponifiable esters. The major compounds in the P. armandii defoliated twig extract were abietane and isopimarane type acids, fatty acids, sterols, labdanoids (cis‐abienol), cembranoids (isocembrol and 4‐epi‐isocembrol), saponifiable sterol esters, and acylglycerols. The same extract of P. kwangtungensis contained larger quantities of fatty acids, caryophyllene oxide, serratanoids, sterols, saponifiable sterol esters, and acylglycerols, but lesser amounts of abietane and isopimarane type acids, cis‐abienol, and lacked cembranoids. Both twig and needle extracts of P. armandii and P. kwangtungensis, as well as the extracts’ fractions, significantly inhibited the growth of Gram‐negative bacteria Serratia marcescens with MIC of 0.1 mg ml^?1, while in most cases they slightly stimulated the growth of Gram‐positive bacteria Bacillus subtilis at the same concentrations. Thus, lipophilic extractive compounds from the needles and defoliated twigs of both pines are prospective for the development of antiseptics against Gram‐negative bacteria.     

White-rot fungal conversion of wheat straw to energy rich cattle feed

In order to improve the digestibility and nutrient availability in rumen, wheat straw was subjected to solid state fermentation (SSF) with white-rot fungi (i.e. Pleurotus ostreatus and Trametes versicolor) and the fermented biomass (called myco-straw) was evaluated for biochemical, enzymatic and nutritional parameters. The fungal treatment after 30 days led to significant decrease (P < 0.05) in cell wall constituents viz, acid detergent fiber (ADF), neutral detergent fiber (NDF), hemicellulose, lignin and cellulose to the extent of 35.00, 38.88, 45.00, 37.48 and 37.86%, respectively in P. ostreatus fermented straw, while 30.04, 33.85, 39.90, 31.29 and 34.00%, respectively in T. versicolor fermented straw. However, maximum efficiency of fermentation in terms of low carbohydrate consumption per unit of lignin degradation, favoring cattle feed production was observed for P. ostreatus on the 10th day (17.12%) as compared with T. versicolor on the 30th day (16.91%). The myco-straw was found to contain significantly high (P < 0.05) crude protein (CP; 4.77% T. versicolor, 5.08% P. ostreatus) as compared to control straw (3.37%). Metabolizable energy (ME, MJ/kg DM), percent organic matter digestibility (OMD) and short chain fatty acids (SCFAs; mmol) production also increased considerably from control straw (4.40, 29.91 and 0.292) to a maximum up to P. ostreatus fermented straw (4.92, 33.39 and 0.376 on 20th day) and T. versicolor fermented straw (4.66, 31.74 and 0.334 on 10th day), respectively. Moreover, the myco-straw had lower organic carbon and was rich in nitrogen with lower C/N ratio as compared to control wheat straw. Results suggest that the fungal fermentation of wheat straw effectively improved CP content, OM digestibility, SCFAs production, ME value and simultaneously lowered the C/N ratio, thus showing potential for bioconversion of lignin rich wheat straw into high energy cattle feed.     

基于LC-MS/MS分析马缨杜鹃花代谢物的变化

为分析马缨杜鹃(Rhododendron delavayi)花开花至凋谢过程中的代谢产物差异及其通路,该文采用LC-MS/MS技术对其花苞期、开裂期、传粉期、盛开期、衰老期和凋谢期的化学成分进行非靶向代谢组学分析。结果表明:(1)共鉴定到973种代谢物,主要包含黄酮类、有机酸、酚酸类、氨基酸及其衍生物、脂类、生物碱等。(2)主成分分析(PCA)表明样本间代谢物存在差异,结合正交偏最小二乘判别分析(OPLS-DA)、t检验的P值和单变量分析的差异倍数(fold-change)筛选差异代谢物(VIP>1,P<0.05,Fc>2或Fc<0.5),涉及591种,在马缨杜鹃花期进入衰老期和凋谢期后差异代谢物数量和表达量显著上升,其中花苞期至开裂期差异代谢物的表达主要呈现下调,而进入衰老期和凋谢期后差异代谢物的表达主要呈现上调。(3)KEGG注释到68条代谢通路,其中差异代谢物极显著富集(P < 0.01)通路3条,包括苯丙素类生物合成、植物激素的生物合成和类黄酮生物合成。(4)结合苯丙素类、黄酮类等有效成分生物合成通路共筛选到10种代谢物包括苯丙氨酸(L-phenylalanine)、反式肉桂酸(trans-cinnamic acid)、查耳酮(chalcone)、柚皮素(naringenin)、对香豆酰基莽草酸(p-coumaroyl shikimic acid)、阿魏酸(ferulic acid)、松柏醇(coniferyl alcohol)、芥子酸(sinapic acid)、紫丁香苷(syringin)、槲皮素(quercetin)。此外,有效成分的差异代谢物表明苯丙素类生物合成代谢活动随马缨杜鹃花的发育逐渐增强,而黄酮类化合物生物合成逐渐减弱,这些关键差异代谢物可能对马缨杜鹃花的发育有重要的调控作用。该研究为马缨杜鹃花开花至凋谢进程中的有效成分代谢途径活性物质的研究提供了代谢组学基础,为进一步研究马缨杜鹃花花期调控的分子机理提供参考。     

Bio-remediation of colored industrial wastewaters by the white-rot fungi Phanerochaete chrysosporium and Pleurotus ostreatus and their enzymes

The effect of Phanerochaete chrysosporium and Pleurotus ostreatus whole cells and their ligninolytic enzymes on models of colored industrial wastewaters was evaluated. Models of acid, direct and reactive dye wastewaters from textile industry have been defined on the basis of discharged amounts, economic relevance and representativeness of chemical structures of the contained dyes. Phanerochaete chrysosporium provided an effective decolourization of direct dye wastewater model, reaching about 45% decolourization in only 1 day of treatment, and about 90% decolourization within 7 days, whilst P. ostreatus was able to decolorize and detoxify acid dye wastewater model providing 40% decolourization in only 1 day, and 60% in 7 days. P. ostreatus growth conditions that induce laccase production (up to 130,000 U/l) were identified, and extra-cellular enzyme mixtures, with known laccase isoenzyme composition, were produced and used in wastewater models decolourization. The mixtures decolorized and detoxified the acid dye wastewater model, suggesting laccases as the main agents of wastewater decolourization by P. ostreatus. A laccase mixture was immobilized by entrapment in Cu-alginate beads, and the immobilized enzymes were shown to be effective in batch decolourization, even after 15 stepwise additions of dye for a total exposure of about 1 month.     

5种杀虫剂对黑粪蚊的毒力及对平菇菌丝生长的影响

[目的]黑粪蚊为食用菌生产中的危险害虫之一,通过杀虫剂的毒力测定和对平菇菌丝生长抑制试验,拟筛选获得理想的黑粪蚊防治杀虫剂。[方法]采用毒饵法测定了5种杀虫剂对黑粪蚊幼虫的室内毒力,并研究各杀虫剂对平菇菌菌丝生长的抑制情况。[结果]20%甲氰菊酯乳油、14%阿维·虫螨腈悬浮剂和20%甲维·吡丙醚悬浮剂对黑粪蚊的校正死亡率达80%以上,对黑粪蚊幼虫均有较好的杀灭效果,而苏云金杆菌（以色列亚种）悬浮剂对黑粪蚊幼虫的杀虫效果不理想。5种杀虫剂对平菇菌丝生长均有一定抑制作用,且农药品种间存在极显著差异,20%甲氰菊酯乳油抑制率最高,高浓度480 mg·L^-1处理的抑制率可达16.85%,14%阿维·虫螨腈悬浮剂的抑制率最低,高浓度140 mg·L^-1处理的抑制率仅为5.83%。[结论]本研究中14%阿维·虫螨腈悬浮剂用于平菇菌中黑粪蚊防治效果最好,研究结果将为食用菌黑粪蚊的药剂防治提供理论指导。     

Disclosure of new and recurrent microbial metabolites by mass spectrometric methods

The application of modern mass spectrometry methods (SI-CID-MS/MS; MS ⁿ ) in the disclosure of new and recurrent microbial metabolites is discussed. Spray ion (SI) sources coupled to different kinds of mass analyzers enable the determination of molecular weights and chemical formulas of given samples even in mixtures. Diagnostic fragment formation by collision-induced dissociation (CID-MS/MS) and MS ⁿ experiments using ion trap mass analyzers are shown as another indispensable source of structural information. Due to the development of benchtop-type mass spectrometers coupled to high-performance liquid chromatography (HPLC), MS can be practised in almost every laboratory as a powerful tool in natural product analysis. Examples are given for special MS applications in identification of bioactive metabolites from screening strains. Journal of Industrial Microbiology & Biotechnology (2001) 27, 136–143. Received 21 September 1999/ Accepted in revised form 19 January 2000     

Differentiation between Commercial Strains of Oyster and Button Mushrooms Using Molecular Markers

Analysis of commercial strains of two edible mushrooms, Pleurotus ostreatus and Agaricus bisporus, using PCR and isozyme electrophoresis techniques allowed us to differentiate groups of genetically similar and distant strains. Among the commercial strains of P. ostreatus, the level of genetic variation was higher suggesting a broader genetic basis employed in breeding of this mushroom. The cultivars and hybrids of A. bisporusshowed a higher level of homology. The isozyme markers (nonspecific esterase, leucinaminopeptidase, and phosphoglucoisomerase) are recommended for identification of the commercial strains of edible mushrooms.     

Decolourization of Municipal Effluent and Sludge by Pleurotus sajor-caju and Pleurotus ostreatus

Summary The Americana Municipal Treatment Station, S?o Paulo, Brazil, manages 400 l of effluent s⁻¹, from domestic and textile origin, which produces an average of 20 t of sludge per day. The decolourization of the effluent and sludge by three strains of Pleurotus (Pleurotus sajor-caju F2, F6 and Pleurotus ostreatus) was evaluated. The strains of P. sajor-caju F2 and F6 were able to decolourize the sludge, while P. ostreatus was less efficient. Detoxification was appraised with three bioassays comprising the cnidarian Hydra attenuata, the alga Selenastrum capricornutum and lettuce seeds. After exposure to fungi, effluent toxicity decreased but not that of its sludge. Strain P. sajor-caju F6 presented signs of toxicity shown by electron microscopy in the presence of the effluent. The three strains produced high amounts of manganese-peroxidase (Mn–P) and laccase in the presence of the sludge. Although P. ostreatus produced large amount of Mn–P and laccase enzymes, these enzymes did not result in decolourization of the sludge, suggesting that other factors are likely to be involved. Carbon content decreased only in the treatment with P. ostreatus.     

Characterization of emodin metabolites in Raji cells by LC–APCI-MS/MS

A rapid, simple, and sensitive liquid chromatography–atmospheric pressure chemical ionization tandem mass spectrometry (LC–APCI-MS/MS) method was developed for the identification and quantification of emodin metabolites in Raji cells, using aloe-emodin as an internal standard. Analyses were performed on an LC system employing a Cosmosil 5C₁₈ AR-II column and a stepwise gradient elution with methanol–20 mM ammonium formate at a flow rate of 1.0 mL/min operating in the negative ion mode. As a result, the starting material emodin and its five metabolites were detected by analyzing extracts of Raji cells that had been cultivated in the presence of emodin. The identification of the metabolites and elucidation of their structures were performed by comparing their retention times and spectral patterns with those of synthetic samples. In addition to the major metabolite 8-O-methylemodin, four other metabolites were assigned as ω-hydroxyemodin, 3-O-methyl-ω-hydroxyemodin, 3-O-methylemodin (physcion), and chrysophanol.     

Antifungal secondary metabolites from endophytic Verticillium sp.

Endophytes were isolated from roots of wild Rehmannia glutinosa to screen the strains with antifungal metabolites. A strain identified as Verticillium sp. was selected for chemical and biological investigations because of the strong antifungal activity of the crude extract against Pyricularia oryzae P-2b. Chemical investigations of culture broth afforded three compounds: 2,6-dihydroxy-2-methyl-7-(prop-1E-enyl)-1-benzofuran-3(2H)-one, massariphenone and ergosterol peroxide. The metabolites were isolated by silica gel and Sephadex LH-20, 2,6-dihydroxy-2-methyl-7-(prop-1E-enyl)-1-benzofuran-3(2H)-one was reported for the first time and the chemical structure was established following the analysis of NMR, UV, IR, MS data. 2,6-Dihydroxy-2-methyl-7-(prop-1E-enyl)-1-benzofuran-3(2H)-one and ergosterol peroxide displayed clear inhibition of the growth of three pathogens as well as Verticillium sp.     

DNA marking of some quantitative trait loci in the cultivated edible mushroom <Emphasis Type="Italic">Pleurotus ostreatus</Emphasis> (Fr.) Kumm.

Fungi of the genus Pleurotus, in particular, species Pleurotus ostreatus (common oyster mushroom) are among most cultivated fungi in the world. Due to intense rates of development of studies in this field, efficient breeding programs are highly required in the search for new P. ostreatus strains. The principal traits used worldwide for selecting strains are intensity of fruitbearing, fruit body cap color (for some consumptive markets), and mycelium growth rate. In this connection, the objective of this work was to study these quantitative traits and to find molecular markers, which could be employed to accomplish breeding programs. In general, we found 12 genomic loci (quantitative trait loci, QTLs) controlling mycelium growth rate of oyster and six QTLs responsible for the fruit body cap color. The genetic map of P. ostreatus was constructed, and all markers of quantitative traits found by us were located on this genetic map. The obtained linkage map can be a useful tool for the accomplishment of breeding programs to improve economically important traits of oyster mushroom.     

Simultaneous analysis of the di(2-ethylhexyl)phthalate metabolites 2-ethylhexanoic acid, 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in urine by gas chromatography–mass spectrometry

A gas chromatographic–mass spectrometric method was developed for the quantitative analysis of the three Di(2-ethylhexyl)phthalate (DEHP) metabolites, 2-ethylhexanoic acid, 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in urine. After oximation with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine hydrochloride and sample clean-up with Chromosorb P filled glass tubes, all three organic acids were converted to their tert.-butyldimethylsilyl derivatives. Quantitation was done with trans-cinnamic acid as internal standard and GC–MS analysis in the selected ion monitoring mode (SIM). Calibration curves for all three acids in the range from 20 to 1000 μg/l showed correlation coefficients from 0.9972 to 0.9986. The relative standard deviation (RSD) values determined in the observed concentration range were between 1.3 and 8.9% for all three acids. Here we report for the first time the identification of 2-ethyl-3-hydroxyhexanoic acid and 2-ethyl-3-oxohexanoic acid in human urine next to the known DEHP metabolite 2-ethylhexanoic acid. In 28 urine samples from healthy persons we found all three acids with mean concentrations of 56.1±13.5 μg/l for 2-ethylhexanoic acid, 104.8± 80.6 μg/l for 2-ethyl-3-hydroxyhexanoic acid and 482.2± 389.5 μg/l for 2-ethyl-3-oxohexanoic acid.     

Cultivation of oyster mushrooms (<Emphasis Type="Italic">Pleurotus</Emphasis> spp.) on various lignocellulosic wastes

Cultivation of speciality mushrooms on lignocellulosic wastes represents one of the most economically and cost-effective organic recycling processes. Three species of Pleurotus, namely P. columbinus, P. sajor-caju and P. ostreatus were experimentally evaluated on untreated organic wastes including chopped office papers, cardboard, sawdust and plant fibres. Production studies were carried out in polyethylene bags of about 1 kg wet weight with 5% spawning rates of substrate fresh weight in a custom-made growth room especially designed for spawn run and cropping. The conversion percentage from dry substrate weight to fresh mushroom weight (biological efficiency) was determined. The highest biological efficiency was noted with P. columbinuson cardboard (134.5%) and paper (100.8%), whereas P. ostreatus produced maximum yield on cardboard (117.5%) followed by paper (112.4%). The overall yield of P. sajor-cajuwas comparatively low (range 47–78.4%). The average number of sporophore flushings ranged between 5 and 6 times. The findings that P. columbinus and P. ostreatus are superior to P. sajor-caju are consistent with previous reports elsewhere. Further evaluation of P. columbinus alone on different bagging systems containing partially pasteurized office papers as a growing substrate revealed that polyethylene bags resulted in 109.4% biological efficiency in contrast to pottery (86%), plastic trays (72%) or polyester net (56%). The above findings reveal an opportunity for commercial implication of oyster mushroom especially P. columbinus for utilization of different feasible and cheap recyclable residues.     

糙皮侧耳和鞘脂菌NS7对多环芳烃污染土壤的生物强化与协同作用

[背景] 真菌和细菌被认为在多环芳烃污染土壤生物修复过程中发挥协同作用,目前在真实土壤体系中开展真菌-细菌协同降解研究较少。[目的] 研究真菌和细菌对不同种类多环芳烃降解的差异及对蒽和苯并[a]蒽的生物强化与协同作用。[方法] 选用多环芳烃降解真菌和细菌各一株,在液体纯培养体系下分析它们对不同种类多环芳烃降解的差异,在土壤体系中采用放射性同位素示踪技术研究2种微生物对蒽和苯并[a]蒽的生物强化与协同作用。[结果] 供试细菌鞘脂菌NS7能够很好地降解低环种类多环芳烃,以蒽作为唯一碳源时可以将其完全降解,在复合污染条件下对菲、蒽、荧蒽、芘等降解效果突出（>90%）,对苯并[a]芘降解效果较差（9.76%）。相比而言,供试真菌糙皮侧耳菌对苯并[a]芘具有更好的降解效果（21.18%）,对低环多环芳烃降解效果明显不如降解菌NS7。在自然土壤中,蒽和苯并[a]蒽具有明显不同的矿化效率,分别为18.61%和4.28%,在蒽污染土壤中加入鞘脂菌NS7并未显著提高蒽的矿化率（P>0.05）,相比而言,苯并[a]蒽污染土壤中加入糙皮侧耳显著提高了污染物矿化效率（2.24倍）,表明真菌和细菌在土壤环境中的定殖存活能力可能影响了生物强化效果。采用灭菌土壤排除土著微生物的竞争排斥作用,研究了真菌菌丝对生物强化降解的影响,发现在蒽污染土壤中,真菌菌丝的迁移作用显著提高了细菌鞘脂菌NS7对污染物的矿化率,从1.75%提高到5.91%;而在苯并[a]蒽灭菌污染土壤中,接种糙皮侧耳却没有发现苯并[a]蒽矿化率提高的现象,表明自然土壤中真菌强化降解苯并[a]蒽的作用可能是源于真菌菌丝促进污染物和土著降解菌的接触,而非直接来自真菌本身。[结论] 细菌能够很好地降解低环种类多环芳烃,而真菌对高环种类多环芳烃降解效果较好。真菌可能通过菌丝促进土著微生物在土壤中的迁移,增大多环芳烃和土著降解菌的接触,从而促进了多环芳烃降解。研究加深了对多环芳烃污染土壤生物强化修复的认识,对发展基于真菌-细菌协同作用的生物强化与调控技术提供理论指导。     

Production of extracellular enzymes by two Pleurotus species using banana pseudostem biomass

The degradation of lignocellulosic biomass of banana pseudoste was investigated during solid state fermentation (SSF) by P. ostreatus and P. sajor-caju. Both organisms proved to be efficient degraders of banana pseudostem biomass. P.ostreatus degraded hemicellulose (40% of dry weight, d.w.) better than cellulose (17.5% of d.w.) and lignin (10% of d.w.). P. sajor-caju also degraded hemicellulose (31% of d.w.) better than cellulose (12.4% of d.w.) and lignin (6% of d.w.). In both cases, a preferential removal of hemicellulose during the initial growth period and a delayed degradation of lignin were observed. The kinetics of cellulolytic, hemicellulolytic and lignolytic enzyme production in liquid culture were also examined. The activities of CMCase and β-glucosidase were highest at 16 days of growth and avicelase activity was at its maximum after 24 days (CMCase - 1.1 IU/ml, β-glucosidase - 0.09 IU/ml in the case of P. ostreatus; CMCase - 1.0 IU/ml, β-glucosidase - 0.087 - IU/ml in the case of P. sajor-caju.). Xylanase and laccase activity reached their maximum after day 16 and day 24 of incubation, respectively. (Xylanase - 1.1 IU/ml and laccase 3.0 IU/ml in the case of P. ostreatus; xylanase - 1.0 IU/ml and laccase - 3.6 IU/ml in the case of P. sajor-caju.). The efficient degrading capacity of test fungi demonstrated their potential use in the conversion of banana pseudostem biomass into mycelial protein-rich fermented animal feed.