Dense fouling in acid transfer pipelines by an acidophilic rubber degrading fungus

An unique case of dense fouling by an acidophilic, hard rubber (polymerized rubber) degrading fungus in the acid transfer pipelines of a boron enrichment plant located at Kalpakkam, India is reported. In spite of a highly adverse environment for survival (pH 1.5, no dissolved nutrients), the fungus thrived and clogged the pipeline used for transferring 0.1N hydrochloric acid (HCl). Detailed investigations were carried out to isolate and identify the fungus and examine the nutrient source for such profuse growth inside the system. Microscopic observation showed the presence of a thick filamentous fungal biomass. Molecular characterization by 18S rRNA gene sequencing showed 98% similarity of the isolate with the acidophilic fungus Bispora sp. In laboratory studies the fungus showed luxuriant growth (specific growth rate of 13 mg day^?1) when scrapings of the hard rubber were used as the sole source of carbon. Scanning electron microscopy revealed extensive incursion of the fungus into the hard rubber matrix. In the laboratory, fungal growth was completely inhibited by the antifungal agent sodium omadine. The study illustrates an interesting example of biofouling under extreme conditions and demonstrates that organisms canphysiologically adapt to grow under unfavourable conditions, provided that a nutrient source is available and competition is low. The use of this fungal strain in biodegradation and in development of environmentally compatible processes for disposal of rubber wastes is envisaged.     

Evidence that γ-aminobutyric acid is a major nitrogen source during Cladosporium fulvum infection of tomato

The growth of the biotrophic pathogen Cladosporium fulvum within the tomato (Lycopersicon esculentum Mill.) leaf is restricted to the intercellular space. Previous studies from this laboratory have demonstrated that gamma-aminobutyric acid (GABA) accumulates to millimolar concentrations in the apoplast during a compatible interaction. We decided to further investigate the role of GABA during infection. A gene encoding a required enzyme for GABA metabolism, GABA transaminase (Gat1), was cloned and sequenced from C. fulvum. The predicted protein sequence of Gat1 had high homology to other fungal GABA transaminases, particularly from Aspergillus nidulans. In vitro expression experiments revealed Gat1 to be strongly expressed during fungal growth on both GABA and glutamate whereas nearly no expression was evident during nitrogen starvation conditions. Expression of Gat1 was also apparent during infection, suggesting for the first time that C. fulvum actively metabolises GABA during infection. This indicates that the fungus may be utilising the GABA in the apoplast as a nutrient source. Further analysis revealed that the expression of tomato glutamate decarboxylase, the enzyme responsible for GABA synthesis, appeared appreciably higher during a compatible interaction than in the incompatible interaction. These findings imply that the infecting fungus may alter the physiology of the tomato leaf with the result that a source of nitrogen is supplied.     

多孔菌Trichaptum abietinum 1302BG自然条件下对合成染料刚果红和酸性品红的高效降解

选用杭州竹林土壤分离并筛选能够降解多种类型染料的真菌。经大量筛选发现一株编号为1302BG的真菌能够在固体培养基上分解所测试的全部9种染料(苯胺蓝、刚果红、橙黄G、甲基红、甲基橙、结晶紫、酸性品红、番红花红、碱性品红、甲基紫)。经形态学和分子生物学方法鉴定, 该菌1302BG为冷杉附毛孔菌(Trichaptum abietinum)。在液体培养基中研究了pH、温度、碳源、氮源、碳氮源组合、碳氮源浓度等参数对该菌脱色效果的影响, 以寻找最适最经济的脱色条件。在液体培养基中研究表明, 冷杉附毛孔菌1302BG既能在酸性又能在碱性条件下有效分解2种测试染料(酸性品红和刚果红)。该真菌能以仅含有0.5 g/L淀粉和0.05 g/L硫酸铵的经济、环境友好的培养基为底物, 能在灭菌和非灭菌(自然)的条件下高效脱色, 在24 h内对2种染料的脱色率均在90%以上。紫外/可见光谱及微核试验分析显示, 该菌脱色主要是以生物降解为主, 2种染料经该菌分解后的毒性也同时大大降低。这些优异特点显示了该菌具有非常广阔的工业染料废水处理应用潜力。     

Biodiesel-derived crude glycerol bioconversion to animal feed: a sustainable option for a biodiesel refinery

This study examined the potential of producing an edible fungus, Rhizopus microsporus var. oligosporus, on biodiesel-derived crude glycerol. Prolific fungal growth was observed with a fungal biomass yield of 0.83 ± 0.02 (g biomass increase/g initial biomass) under optimal cultivation conditions (e.g. nonsterile crude glycerol at a concentration of 75% (w/v) with nutrient supplementation and without pH control). The potential of utilizing front-end processed banagrass (Pennisetum purpureum) juice as a source of nutrients for crude glycerol fermentation was evaluated with a 2.3-fold improvement in the fungal biomass yield. The glycerol-derived fungal biomass showed high amounts of threonine, one of the main limiting amino acids in non-ruminant feeds. An inexpensive fungal protein has the potential to reduce meat product prices by lowering the production costs of animal feeds. The application of fungal technology thus provides a unique sustainable option for biodiesel refineries by providing an additional source of revenue from fungal products.     

Presymbiotic growth and sporal morphology are affected in the arbuscular mycorrhizal fungus Gigaspora margarita cured of its endobacteria

Some arbuscular mycorrhizal fungi contain endocellular bacteria. In Gigaspora margarita BEG 34, a homogenous population of beta-Proteobacteria is hosted inside the fungal spore. The bacteria, named Candidatus Glomeribacter gigasporarum, are vertically transmitted through fungal spore generations. Here we report how a protocol based on repeated passages through single-spore inocula caused dilution of the initial bacterial population eventually leading to cured spores. Spores of this line had a distinct phenotype regarding cytoplasm organization, vacuole morphology, cell wall organization, lipid bodies and pigment granules. The absence of bacteria severely affected presymbiotic fungal growth such as hyphal elongation and branching after root exudate treatment, suggesting that Ca. Glomeribacter gigasporarum is important for optimal development of its fungal host. Under laboratory conditions, the cured fungus could be propagated, i.e. could form mycorrhizae and sporulate, and can therefore be considered as a stable variant of the wild type. The results demonstrated that - at least for the G. margarita BEG 34 isolate - the absence of endobacteria affects the spore phenotype of the fungal host, and causes delays in the growth of germinating mycelium, possibly affecting its ecological fitness. This cured line is the first manipulated and stable isolate of an arbuscular mycorrhizal fungus.     

Slow and steady phosphate solubilization by a psychrotolerant strain of <Emphasis Type="Italic">Paecilomyces</Emphasis><Emphasis Type="Italic">hepiali</Emphasis> (MTCC 9621)

A psychrotolerant phosphate solubilizing fungus has been isolated from the rock soil of a cold desert site in Indian Himalaya. The fungus grows from 4 to 35°C (optimum 21°C), and from 2 to 13.5 pH (optimum 9) under laboratory conditions. Based on phenotypic characters and 26S rDNA analysis, the fungus is identified as Paecilomyces hepiali. In quantitative estimation that was carried out at 9, 14, and 21°C, the fungus solubilized maximum phosphate at 14°C. In view of the slow growth and persistence of the desired activity at low temperature, the estimation was carried out for a longer period, i.e., up to 6 weeks. The suboptimal conditions for growth and biomass production were found to be optimal for phosphate solubilization by the fungus. At 14 and 9°C, the solubilization touched its maximum on day 42. Decline in pH was found to be significantly correlated with the phosphate solubilization at all the temperatures, under consideration. The acid phosphatase activity was found to be more prominent than alkaline phosphatase in culture filtrate. High performance thin layer chromatography (HPTLC) analysis showed production of six organic acids, gluconic and α-keto glutaric acid being in maximum amount in the culture filtrate. The study has ecological significance in view of the nutrient cycling under low temperature environment, prevalent in Himalayan region.     

Zinc-tolerant Suillus bovinus improves growth of Zn-exposed Pinus sylvestris seedlings

Scots pine (Pinus sylvestris L.) seedlings inoculated or not (NM) by a Zn-sensitive or a Zn-tolerant isolate of the ectomycorrhizal fungus Suillus bovinus (L. Fr.) Roussel were exposed to 0.1 or 150 μM Zn²⁺ for 9 months. We hypothesized that inoculation with a Zn-tolerant S. bovinus isolate should result in added Zn resistance of the host plant. Plant and fungal growth as well as nutrient profiles and photosynthetic pigments in pine needles were quantified. In NM plants and in plants colonized by the Zn-sensitive isolate, plant growth, N, P, Mg and Fe assimilation were strongly inhibited under Zn stress and concurred with significantly reduced chlorophyll concentrations. In contrast, plants colonized by the Zn-tolerant isolate grew much better and remained physiologically healthier when exposed to elevated Zn. These results provide further evidence for the important role metal-adapted mycorrhizal fungi play as an effective biological barrier against metal toxicity in trees.     

薄皮干酪菌生物学特性及驯化栽培

大型真菌种质资源是国家种质资源库建设重要组成部分,为了充分开发利用大型真菌资源,对采自吉林省寒葱岭的一株野生菌进行分离纯化,并将获取的纯菌株作为实验材料。通过形态学和ITS序列分析,将其鉴定为薄皮干酪菌Tyromyces chioneus。本实验研究了固体培养条件下不同碳源、氮源、pH和温度对其菌丝生长的影响,并从4个单因素实验中选出3个最优水平进行正交实验。同时,在对其菌丝体最适培养条件研究结果的基础上,对其进行驯化栽培研究。结果表明,薄皮干酪菌的最适培养条件为：果糖(20 g/L)、酵母浸粉(2 g/L)、pH 4.0、温度30 ℃。正交实验结果表明,氮源对其菌丝体生长的影响最大,其次是碳源、pH和温度。驯化栽培结果表明,菌丝发菌时间为21 d;空气湿度为85%-95%,适量的散射光,降低温度至18-20 ℃刺激后原基逐步变成菇蕾,将温度、湿度分别提高至24-25 ℃、90%-98%,30 d后子实体成熟。通过本实验的研究为薄皮干酪菌的后续开发利用提供了基础实验数据。     

First report of Bipolaris bicolor causing a leaf spot disease on rubber tree

The rubber tree (Hevea brasiliensis) is the only resource for commercial natural rubber production and thus has economic importance in Southeast Asia. A spot disease on the leaves of a rubber tree was first discovered in 2017 in Hainan, China. In this study, the fungal isolate MA1 from the infected tissues was determined to be a pathogen of the spot disease by satisfying Koch's postulates. The isolate MA1 was identified as Bipolaris bicolor based on the morphological characteristics and multigene phylogenetic analysis. Among fungicides, prochloraz, iprodione and pyraclostrobin significantly inhibited hyphal growth of B. bicolor under in vitro conditions. This study constitutes the first report on the association of B. bicolor with leaf spot disease of rubber trees worldwide.     

Arbuscular mycorrhizal adaptation,spore germination,root colonization,and host plant growth and mineral acquisition at low pH

Arbuscular mycorrhizal (AM) fungi colonize plant roots and often enhance host plant growth and mineral acquisition, particularly for plants grown under low nutrient and mineral stress conditions. Information about AM fungi and mycorrhizal ( +AM) host plant responses at low pH ( < 5) is limited. Acaulospora are widely reported in acid soil, and Gigaspora sp. appear to be more common in acid soils than Glomus sp. Spores of some AM fungi are more tolerant to acid conditions and high Al than others; t Acaulospora sp., Gigaspora sp., and Glomus manihotis are particularly tolerant. Root colonization is generally less in low than in high pH soils. Percentage root colonization is generally not related to dry matter (DM) produced. Maximum enhancement of plant growth in acid soil varies with AM fungal isolate and soil pH, indicating adaptation of AM isolates to edaphic conditions. Acquisition of many mineral nutrients other than P and Zn is enhanced by +AM plants in acid soil, and the minerals whose concentration is enhanced are those commonly deficient in acid soils (Ca, Mg, and K). Some AM fungal isolates are effective in overcoming soil acidity factors, especially Al toxicity, that restrict plant growth at low pH.     

Effect of phenolic monomers on biomass and hydrolytic enzyme activities of an anaerobic fungus isolated from wild nil gai (Baselophus tragocamelus)

AIMS: To test the anaerobic fungus, Piromyces sp. FNG5, for its tolerance to phenolic monomers released in the rumen by degradation of lignocellulosic poor-quality feeds. METHODS AND RESULTS: Effects of phenolic monomers on biomass and fibrolytic enzyme activities of a pure culture of lignocellulolytic anaerobic fungus (Piromyces sp. FNG5) isolated from faeces of wild nil gai (blue bull, Baselophus tragocamelus) were evaluated. There was a reduction in fungal biomass at 1 mm concentration of catechol with complete inhibition at 10 mm. p-Coumaric acid caused a reduction in biomass at 10 mm and no growth was observed above 20 mm concentration. The fungal isolate could tolerate up to 5 mm of ferulic acid without any reduction in biomass level, and was able to grow to some extent up to the highest level of ferulic acid tested (20 mm). Vanillic acid had no effect on biomass of the fungus even up to 50 mm level. The phenolic monomers varied in their potential to inhibit the secretion of carboxymethyl cellulase, xylanase, beta-glucosidase and acetyl esterase activities with catechol being the most inhibitory and vanillic acid being the least inhibitory. After 14 days of incubation, 38.49-65.14%p-Coumaric acid, 65.22-74.10% ferulic acid and 34.13-66.78% vanillic acid disappeared from the medium under anaerobic conditions. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: It is concluded that the anaerobic fungus Piromyces sp. FNG5 is tolerant to phenolic monomers and has ability to degrade them. Therefore, such anaerobic fungi may play an important role in fibre degradation in the rumen.     

First evidence of mineralization of petroleum asphaltenes by a strain of Neosartorya fischeri

A fungal strain isolated from a microbial consortium growing in a natural asphalt lake is able to grow in purified asphaltenes as the only source of carbon and energy. The asphaltenes were rigorously purified in order to avoid contamination from other petroleum fractions. In addition, most of petroporphyrins were removed. The 18S rRNA and β‐tubulin genomic sequences, as well as some morphologic characteristics, indicate that the isolate is Neosartorya fischeri. After 11 weeks of growth, the fungus is able to metabolize 15.5% of the asphaltenic carbon, including 13.2% transformed to CO₂. In a medium containing asphaltenes as the sole source of carbon and energy, the fungal isolate produces extracellular laccase activity, which is not detected when the fungus grow in a rich medium. The results obtained in this work clearly demonstrate that there are microorganisms able to metabolize and mineralize asphaltenes, which is considered the most recalcitrant petroleum fraction.     

Bacteria associated with Stagonospora (Septoria) nodorum increase pathogenicity of the fungus

In studies with a laboratory isolate of the fungal pathogen Stagonospora ( Septoria ) nodorum three different isolates of bacteria were closely associated with the fungus. Bacteria were also closely associated with fresh isolates of S. nodorum obtained from artificially and naturally infected field material. Although a range of bacteria was isolated, only one type of bacterium was found to be associated with each isolate of S. nodorum . In co-inoculation studies with pycnidiospores of the fungus on detached leaves, some of the bacterial isolates significantly increased the pathogenicity of the fungus, particularly Xanthomonas maltophilia , Sphingobacterium multivorum , Enterobacter agglomerans and Erwinia amylovora . Evidence is presented indicating that one of the ways that the 'helper bacteria' may assist in the establishment of infections is by the production of lipases that were not detected in germinating fungal spores.     

Sequential batch culture studies for the decolorisation of reactive dye by Coriolus versicolor

The white rot fungus Coriolus versicolor could decolorise reactive dye Remazol Brilliant Violet to almost 90%. The fungal mycelia removed color as well as COD up to 95% and 75%, respectively, in a batch reactor. Decolorising activity was observed during the repeated reuse of the fungus. It was possible to substantially increase the dye decolorising activity of the fungus by carefully selecting the operational conditions such as media composition, age of fungus and nitrogen source. The fungal pellets could be used for eight cycles during the long term operation, where medium and dye was replenished at the end of each cycle and the fungus was recycled. Presence of a nitrogen source and nutrient content of media played an important role in sustaining the decolorisation activity of the fungus. The form of nitrogen source (e.g. peptone vs. urea) was also important to maintain the decolorising activity with peptone showing better decolorisation.     

The physiologic role of alternative oxidase in Ustilago maydis

Alternative oxidase (AOX) is a ubiquitous respiratory enzyme found in plants, fungi, protists and some bacterial species. One of the major questions about this enzyme is related to its metabolic role(s) in cellular physiology, due to its capacity to bypass the proton-pumping cytochrome pathway, and as a consequence it has great energy-wasting potential. In this study, the physiological role and regulatory mechanisms of AOX in the fungal phytopathogen Ustilago maydis were studied. We found evidence for at least two metabolic functions for AOX in this organism, as a major part of the oxidative stress-handling machinery, a well-described issue, and as part of the mechanisms that increase the metabolic plasticity of the cell, a role that might be valuable for organisms exposed to variations in temperature, nutrient source and availability, and biotic or abiotic factors that limit the activity of the cytochrome pathway. Experiments under different culture conditions of ecological significance for this organism revealed that AOX activity is modified by the growth stage of the culture, amino acid availability and growth temperature. In addition, nucleotide content, stimulation of AOX by AMP and respiratory rates obtained after inhibition of the cytochrome pathway showed that fungal/protist AOX is activated under low-energy conditions, in contrast to plant AOX, which is activated under high-energy conditions. An estimation of the contribution of AOX to cell respiration was performed by comparing the steady-state concentration of adenine nucleotides, the mitochondrial membrane potential, and the respiratory rate.     

Metabolic response against sulfur-containing heterocyclic compounds by the lignin-degrading basidiomycete Coriolus versicolor

The fungal conversions of sulfur-containing heterocyclic compounds were investigated using the lignin-degrading basidiomycete Coriolus versicolor. The fungus metabolized a series of sulfur compounds--25 structurally related thiophene derivatives--via several different pathways. Under primary metabolic conditions, C. versicolor utilized thiophenes, such as 2-hydroxymethyl-, 2-formyl-, and 2-carboxyl-thiophenes, as a nutrient sulfur source for growth; thus, the fungus degraded these compounds more effectively in a non-sulfur-containing medium than in conventional medium. The product analysis revealed that several redox reactions, decarboxylation reactions, and C-S cleavage reactions were involved in the fungal conversion of non-aromatic thiophenes. On the other hand, benzothiophene (BT) and dibenzothiophene (DBT) skeletons were converted to water-soluble products. All the products and metabolic intermediates were more hydrophilic than the starting substrates. These metabolic actions seemed to be a chemical stress response against exogenously added xenobiotics. These metabolic reactions were optimized under ligninolytic conditions, also suggesting the occurrence of a fungal xenobiotic response. Furthermore, the fungus converted a series of BTs and DBTs via several different pathways, which seemed to be controlled by the chemical structure of the substrates. DBT, 4-methylDBT, 4, 6-dimethylDBT, 2-methylBT, and 7-methylBT were immediately oxidized to their S-oxides. BTs and DBTs with the hydroxymethyl substituent were converted to their xylosides without S-oxidation. Those with carboxyl and formyl substituents were reduced to form a hydroxymethyl group, then xylosidated. These observations strongly suggested the involvement of a fungal substrate-recognition and metabolic response mechanism in the metabolism of sulfur-containing heterocyclic compounds by C. versicolor.     

Differential diagnosis of enterococci]

The most stable differential signs of enterococci are: growth in the medium at pH 10.2, growth in broth containing 40% bile, citrate utilization, resistance to 0,05% potassium tellurite, 2, 3, 5-triphenyltetrazolium chloride (TTC) reduction, the staining of colonies (plaques) on a medium with manganese, iron and zinc salts, glycerine fermentation under anaerobic conditions, mannite fermentation, the presence of hemolysin, of the proteolytic enzyme, and mobility. Combined differential-diagnostic nutrient medium permits to determine simultaneously 5 enterococci signs--resistance to nalidixic acid and to crystal violet, TTC reduction, hemolytic and proteolytic activity. The suggested scheme of enterococci laboratory diagnosis including a set of hard nutrient media poured into multisection Petri dish is simple reliable and accessible for any bacteriological laboratory.     

Diuron degradation by Phanerochaete chrysosporium BKM- F-1767 in synthetic and natural media

When incubated in synthetic (N-limited) medium and on ashwood chips, Phanerochaete chrysosporium BKM-F-1767 degraded 14 and 10 mg/l diuron, respectively. The wood chips were used as support and sole nutrient source for the fungus. A higher degradation efficiency was found in ashwood culture as compared to the liquid culture, probably as a result of the synergetic effect of attached fungal growth, presence of limiting-substrate conditions and the microenvironment provided by ashwood, all favorable for production of high extracellular enzyme titres. Diuron degradation occured during the idiophasic growth, in the presence of manganese peroxidase, detected as dominant enzyme in both cultures.     

Trees,Mycorrhiza and Minerals –Field Relevance of in vitro Experiments

Ectomycorrhizal fungi are mutualistic symbionts of boreal forest trees and may mediate mineral weathering through their direct access to photosyntentically derived carbon. In soil, fungal mycelia (i) provide a large surface for nutrient uptake; (ii) induce intense colonization of nutrient rich substrates; (iii) cause local acidification and (iv) produce organic acids. Mechanisms of ectomyorrhizal fungi induced weathering in response to nutrient limiting growth conditions remains largely unresolved. This review summarizes how current knowledge on fungal weathering is affected by experimental setup and conditions, i.e., pure or symbiotic growth, nitrogen source, the mean of detecting weathering activity and species examined.     

Influence of complex nutrient source on growth of and curvacin a production by sausage isolate Lactobacillus curvatus LTH 1174

Lactobacillus curvatus LTH 1174, a fermented sausage isolate, produces the antilisterial bacteriocin curvacin A. Its biokinetics of cell growth and bacteriocin production as a function of various concentrations of a complex nutrient source were investigated in vitro during laboratory fermentations with modified MRS medium. A modification of the nutrient depletion model was used to fit the data describing growth and bacteriocin production. Both cell growth and bacteriocin activity were influenced by changes in the complex nutrient source concentration. Standard MRS medium clearly limited the growth of L. curvatus LTH 1174. Higher nutrient concentrations, up to a certain degree, led to improved growth, a higher attainable biomass concentration, and a higher bacteriocin activity in the supernatant. A lower concentration of complex nutrient source caused severe growth inhibition, leading to a lower biomass concentration but a much higher specific bacteriocin production. When examining the separate components of the complex nutrient source, a stimulating effect of bacteriological peptone on growth was found without an adverse effect on bacteriocin production, resulting in increased curvacin A activity. Furthermore, specific depletion of the amino acids tyrosine, serine, and asparagine/aspartic acid was observed for this strain.