Effect of storage environment on carrot root rots and biochemical changes during storage

 The optimum temperature and relative humidity for the development of carrot root rot during storage were found to be 20°C and 60%, respectively, and rot development increased as these environmental factors increased in magnitude. Temperature and relative humidity both enhance the biodeterioration of the carrot root through an increase in the diameter the rotted area of infected roots. The rot during storage was found to be caused by Rhizopus oryzae, Trichoderma harzianum, Botryodiplodia theobromae, Aspergillus niger and Aspergillus flavus. The fungi enter through wounds and natural openings. The amounts of total soluble sugar in rotted carrot root were substantially decreased 2 – 4 days after infection and paper chromatography showed the presence of glucose, maltose, sucrose, lactose and galactose in healthy carrot roots, while only lactose and galactose were present in infected roots. The ascorbic acid, total nitrogen, crude protein, crude fibre, fat and mineral contens in infected carrot roots reduced as the storage period was prolonged. Received: 16 October 1996     

Fungal strains isolated from cork stoppers and the formation of 2,4,6-trichloroanisole involved in the cork taint of wine

Cork taint is mainly due to 2,4,6-trichloroanisole (TCA) produced through the activity of undesirable fungal strains. We observed that CFU mould number in TCA-containing stoppers was not quantitatively different to that of the stoppers not containing TCA (ca. 10(5)CFU/g). In contrast more fungi diversity was observed in TCA-containing stoppers. Penicillium spp (Penicillium chrysogenum, Penicillium glabrum), Aspergillus spp (Aspergillus niger and Aspergillus oryzae), Chrysonilia sitophila, Mucor racemosus, Paecilomyces sp. and Trichoderma viride were found in TCA-containing stoppers, while C. sitophila and Penicillium sp. were the main fungi in the stoppers devoid of TCA. Conidia were numerous close to the lenticels and present from the lateral surface through to the centre of the stoppers. Strains of Aspergillus, Mucor, Paecilomyces, Penicillium and Trichoderma isolated from TCA-containing stoppers were able to convert 2,4,6-trichlorophenol (TCP) in TCA in resting cell or growing conditions. The best yields of conversion were obtained by green fungi Paecilomyces sp. and P. chrysogenum, 17% and 20%, respectively. Chysonilia sitophila and Penicillium sp. did not produce TCA from TCP in our conditions.     

几种捕食真菌对烟草根结线虫致病力研究初报

本文应用捕食真菌Ａｒｔｈｒｏｂｏｔｒｙｓｏｌｉｇｏｓｐｏｒａ，Ａ．ｍｕｓｉｆｏｒｍｉｓ，Ａ．ｃｌａｄｏｄｅｓ，Ａ．Ｖｅｒｍｉｃｏｌａ，Ｍｏｎａｃｒｏｓｐｏｒｉｕｍｌｙｓｉｐａｇａ，Ｍ．ｍｅｇａｌｏｓｐｏｒｕｍ，Ｍ．ｍｕｔａｂｃｌｅ，对南方根结线虫（Ｍｅｌｏｉｄｏｇｙｎｅｉｎｃｏｇｎｉｔａ）进行了致病力测定和捕食过程观察，结果表明：各菌株对根结线虫二龄幼虫均具有致病性，Ａｒｔｈｒｏｂｏｔｒｙｓ属菌种以三维粘性菌网捕食，Ａ．ｏｌｉｇｏｓｐｏｒａ捕食率最高；Ｍｏｎａｃｒｏｓｐｏｒｉｕｍ属菌种形成粘着孢和非收缩环两种捕食器官。     

FUNGAL-INDUCED REDISTRIBUTION OF KRAFT LIGNIN MOLECULAR WEIGHT BY MULTI-ANGLE LASER LIGHT SCATTERING

Culture broths from Phanerochaete chrysosporium and Trametes cingulata, combined with co-factors such as hydrogen peroxide, dithiothreitol, copper, iron, and manganese ions were examined for the ability to modify lignin structure. High-performance size exclusion chromatography (HP-SEC) coupled to multi-angle laser light scattering (MALLS) detection was used to determine the effect of several white rot fungi, pH values, enzymes, and co-factors on the molecular weight distribution of treated kraft lignin. The analytical procedure tracked changes in molecular weight distribution, radius of gyration, and hydrodynamic radius. Results showed changes in the molecular weight distribution of lignin components when treated with combinations of factors. The induced cultures showed more lignin depolymerization for the specific lignin samples in which they were initially grown. The distribution in the radius of gyration became narrower with time, indicating that molecular conformation changed to a more uniform molecular shape. H₂O₂ and DTT showed the most significant changes in lignin molecular weight distribution.     

Ozone Gas Antifungal Effect on Extruded Dog Food Contaminated with Aspergillus flavus

ABSTRACT

Decontamination of Aspergillus flavus spores in inoculated extruded food (Standard and Super-Premium types), through ozone (O₃) gas, was investigated at different concentrations (40 and 60 µmol/mol) and times (30, 60, and 120 min) of exposure. The gas antifungal efficiency, humidity, and lipid stability were evaluated before and after treatments. O₃ reduced A. flavus spores of the extruded food, on both types (p < 0.05). The highest reduction (98.3%) was observed for both food types, when gas was applied for 120 min, regardless of the O₃ concentration. Regarding humidity and peroxide index, there was no difference, either prior to or after the gas application for all treatments conditions. O₃ gas can be an efficient method for fungi spores’ contamination control during commercialization of extruded food in open bags exposed to the environment.     

蛇足石杉内生真菌的研究进展

蛇足石杉由于其治疗老年痴呆等疾病,具有特殊的药用价值和潜在的巨大经济价值,正日益受到国内外的关注。本文综述了近年来国内外对蛇足石杉内生真菌的生物学性状、分离纯化、菌种鉴定、发酵产物及活性筛选等方面的研究现状,并提出一些建议,对未来蛇足石杉内生真菌的研究进行了展望。     

New insights concerning the occurrence of fungi in water sources and their potential pathogenicity

Fungi are known to occur ubiquitously in the environment. In the past years, the occurrence of filamentous fungi in the aquatic environment has been a subject of growing interest. This study describes the occurrence of various fungal genera in different drinking water sources being Penicillium and Trichoderma the most representative ones (30% and 17%, respectively). Also, 24 fungal species that have not been previously described in the aquatic environment are reported in this study, being once again the major species from the Penicillium genera. This study therefore contributes to the knowledge on the richness of fungi diversity in water. 68% of the described species were found to be able to grow at 30 °C but only Aspergillus fumigatus, Aspergillus viridinutans and Cunninghamella bertholletiae were able to grow at the higher temperature tested (42 °C). 66% of the species that were able to grow at 30 °C have spore sizes below 5 μm which enables them to cause breathing infections. These were therefore identified as potential pathogenic species.     

Effect of moisture‐damage intervention on the immunotoxic potential and microbial content of airborne particles and on occupants' upper airway inflammatory responses

This intervention study evaluated the effect of moisture‐damage repairs on the exposure and on the upper airway inflammatory responses of the occupants. The airborne microbial exposure was followed by quantitative PCR analyses of 13 microbial species in repeated long‐term indoor air samples before (N = 26) and after (N = 28) repairs of the school building. Airborne particulate matter was collected similarly from the same premises (before N = 25, after N = 34) for determination of nitric oxide (NO), tumor necrosis factor α (TNFα), and interleukin‐6 (IL‐6), measured in the cell culture medium of mouse macrophages. NO, TNFα, IL‐6, and IL‐4 were also analyzed in the nasal lavage (NAL) samples of the occupants (N = 13) to characterize their upper airway inflammatory responses during the exposure and after its cessation. After the repairs, concentrations of the measured airborne microbes decreased, the difference being significant for six of 13 species. After renovation, airborne particulate matter also caused significantly lower production of IL‐6 and TNF‐α in mouse macrophages than the material collected before the renovation. The concentration of IL‐4 in the NAL samples was significantly lower after the renovation. These results show that the inflammatory potential of the airborne material decreases after intensive repair of the moisture damage.     

Airborne fungal cell fragments in homes in relation to total fungal biomass

Fungal exposure may induce respiratory symptoms. The causative agents are compounds in the fungal cell wall. Fragments of microbes may be present in air samples but are not measurable using conventional spore counting or by the determination of viable organisms. This study assesses the proportion of fungal cell biomass and endotoxin in different particle size fractions in air samples from homes. Air samples were collected from 15 homes using a cyclone sampler, collecting particles in three aerodynamic size fractions: <1.0, 1.0–1.8, and >1.8 μm. N‐Acetylhexosaminidase (NAHA) was determined as a marker of fungal cell biomass. Endotoxin was determined using the Limulus amebocyte lysate method. NAHA and endotoxin in the size range <1.0 μm comprised up to 63% (mean 22.7%) and 96.3% (mean 22.6%) of the total concentrations, respectively. There were significant relationships between the amounts of NAHA and endotoxin in the total amount and in the size fraction >1.8 μm but not in the smaller fractions. The results demonstrate significant amounts of fungal cell biomass and endotoxin in particles <1.0 μm. Homes with reported mold damage had a lower concentration of NAHA in particles <1.0 μm than homes without mold damage. To assess airborne exposure for diagnostic and preventive purposes, measurement techniques that include this fraction should be considered.