Bioconversion of acid- and gamma-ray-treated sweet potato residue to microbial protein by mixed cultures

Sweet potato residue, a starchy agricultural waste, was used as a substrate to produce microbial protein by Fusarium moniliforme and Saccharomyces cerevisiae in submerged fermentation. Acid- and gamma-irradiation-pretreated sweet potato residue enhanced the biomass yield and protein production when the residue was fermented with F. moniliforme and S. cerevisiae. A mixed culture of F. moniliforme and S. cerevisiae efficiently and rapidly utilized free sugars; the maximal biomass yield (13.96 g/l) and protein production (65.8%) were obtained after 3 days fermentation. Lower carbon utilization by the two microbial strains occurred in the waste-containing media as compared to control, increasing the economic value of the waste usage. Received 25 October 2001/ Accepted in revised form 22 June 2002     

Comparative studies of hepatotoxicity and fumonisin B1 and B2 content of water and chloroform/methanol extracts of Fusarium moniliforme strain MRC 826 culture material

Fusarium moniliforme has been associated with several diseases including equine leukoencephalomalacia, human esophageal cancer and hepatotoxicity/hepatocarcinogenicity in laboratory animals. The potential health risks to animals and humans posed by F. moniliforme contaminated grains cannot be assessed until the toxins are identified and toxicologically evaluated. As part of a systematic approach to identifying the hepatotoxins produced by F. moniliforme, diets containing aqueous and chloroform/methanol (11) extracts of F. moniliforme strain MRC 826 culture material (CM) and/or the extracted CM residues were fed to male Sprague-Dawley rats for four weeks. Serum alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase activities were increased after two and four weeks and microscopic liver lesions were found in those animals fed aqueous CM extract and the CM residue after chloroform/ methanol extraction. Fumonisins B₁ and B₂ were extracted from the CM by water, but not chloroform/ methanol, and were present in the toxic diets at concentrations of 93–139 and 82–147 ppm, respectively. Nontoxic diets contained 22 ppm fumonisin B₁ and 65 ppm fumonisin B₂.Abbreviations CM culture material - ELEM equine leukoencephalomalacia Mention of a trademark, proprietory name or vendor does not imply its approval by the US Department of Agriculture to the exclusion of others that may also be suitable.     

Actinomycotic intracavitary lung colonization

We describe four cases of actinomycotic intracavitary lung colonization and review the literature on the subject. Aspergillus fumigatus, A. niger, A. flavus, Pseudallescheria boydii are responsable for the majority of fungi intracavitary lung colonization (fungus ball). The similarities in clinical symptom (haemoptysis) and radiologic feature (pulmonary air meniscus) of fungus ball and actinomycotic intracavitary colonization prompted the investigation into a range of microorganisms, including Nocardia spp. [2–6] and Actinomyces spp. [1–5]. We report four cases of such actinomycotic syndrome, three of them in diabetic patients, and review briefly the literature.     

Detoxification of aflatoxins in groundnut meal

An attempt was made to detoxify aflatoxic groundnut meal with ammonia during pelleting in order to develop a cheap and rapid detoxification process. These experiments were not successful but storage with ammonia gave a high degree of detoxification. Thus, a detoxification above 99% is obtained when ground groundnut meal is stored with 5% NH₃ and 20% water for 10 days in tight plastic bags. The treatment results in a decline in NPU of about 10%, relatively, as determined with rats, but conversely the content of NPN is increased. The detoxified meal is most likely to be used as an ingredient in compounded rations for ruminants where the NPN (ammonia) will be of value as a nutrient. A feeding experiment with dairy cattle showed an 80% decline of aflatoxin M₁ in the milk when a 93% detoxified groundnut meal was used as a feed ingredient.     

Fumonisin and Beauvericin Induce Apoptosis in Turkey Peripheral Blood Lymphocytes

Fumonisins, a family of mycotoxins produced by Fusarium verticillioides (synonym Fusarium moniliforme Sheldon) and F. proliferatum, have been associated with various deleterious effects in different animal species. Serological, hematological and pathological effects and mortality have previously been observed in broiler chicks fed F. proliferatum culture material containing known concentrations of fumonisin, moniliformin and beauvericin. Turkey peripheral blood lymphocytes were exposed in vitro for 72 hours to fumonisin B₁(FB₁), fumonisin B₂(FB₂), hydrolyzed fumonisin B₁ (HFB₁), moniliformin and tricarballylic acid (TCA) (0.01-25 g/ml). A decrease in cell proliferation, as determined by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] bioassay, occurred in the order: FB₂ > FB₁ > HFB₁, with IC₅₀ = 0.6 M, 1 M and 10 M, respectively. Internucleosomal DNA fragmentation and morphological features characteristic of apoptosis were observed following exposure to fumonisin B₁ and beauvericin; cytoplasmic condensation and membrane blebbing were seen by light microscopy. Tricarballylic acid and moniliformin did not interfere with cell proliferation. Results suggested that fumonisin B₁ and beauvericin may affect immune functions by suppressing proliferation and inducing apoptosis of lymphocytes.     

Case report: Prosthetic valve endocarditis caused by Pseudallescheria boydii and Clostridium limosum

This report describes a patient with a combined infection due to Pseudallescheria boydii and Clostridium limosum on a prosthetic dura mater aortic valve homograft. While this patient had C. limosum only growing in blood cultures, both organisms were isolated from the surgically resected aortic valve. Because P. boydii is generally resistant to amphotericin B but susceptible to miconazole, accurate differentiation of P. boydii from other fungi which may appear similarly in tissue sections (e.g., aspergillus) is important.     

Moniliformin produced by cultures of Fusarium moniliforme var. subglutinans isolated from swine feed

Feed samples from Iowa suspected of causing vomiting and enlarged vulva as well as mortalities of swine were examined for toxigenic fungi and mycotoxins Fusarium moniliforme Sheldon and F. moniliforme Sheldon var. subglutinans Wollenew. & Reink. accounted for 43% and 18.5%, respectively, of the total count of 4.75×10⁵ propagules filamentous fungi per gram of swine feed, but representatives of various Penicillium spp. and Aspergillus spp. were also found. Eight isolates of F. moniliforme var. subglutinans from the feed produced 51–540 g of moniliformin per g on cracked corn at 25°C for six weeks. Zearalenone was not detected in these corn fermentations. Eight isolates of F. moniliforme from the feed did not produce detectable amounts of either zearalenone or monoliformin on cracked corn. Moniliformin was not detected in the feed samples.     

The action of plant growth retardants on terpenoid biosynthesis

Summary The plant growth retardants (2-chloroethyl)-trimethylammonium chloride (CCC) and 2-isopropyl-4-(trimethylammoniumchloride)-5-methylphenyl-piperidine-1-carboxylate (AMO-1618) inhibit gibberellic-acid biosynthesis inFusarium moniliforme at the cyclisation of geranylgeraniol to (-)-kaurene, causing an accumulation of geranylgeraniol. The two inhibitors have no effect on the biosynthesis of ergosterol inF. moniliforme or sitosterol in barley seedlings.     

Synthesis of shorter active analogues of Bactenecin7: The effect of change of N-terminal configuration on antimicrobial activity

Bactenecin7, a cationic antibacterial peptide, contains a repeating region of Xaa-Pro-Arg-Pro (Xaa = hydrophobic residues). A series of peptides, Xaa-Pro-Arg-Pro (Xaa = D-Ala, D-Leu, D-Val, D-Phe and D-Lys) were synthesized to investigate the effect of change of N-terminal configuration on antimicrobial activity. The conformationalpreferences of these peptides in water and TFE were examined by circular dichroism. All the synthetic peptides with D-amino acid substitution at N-terminal showed potent antifungal activity against Aspergillus niger, Aspergillus flavus and Fusarium moniliforme at the concentration level of 8–10 g ml^-1. But the same tetrapeptides were unable to kill or suppress the growth of gram-negativeand gram-positive bacteria such as Escherichia coli HB101, Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus even at the concentration level of 400 g ml^-1. The present study reveals that the change of configuration at the N-terminal of tetrapeptide has negative impact on antibacterial activity but enhanced antifungal activity.     

Extracellular Peptidase in the Fungal Pathogen Pseudallescheria boydii

Pseudallescheria boydii is a ubiquitous filamentous fungus capable of causing invasive disease in humans. In the present study, using sodium dodecyl sulfate–polyacrylamide gels containing bovine serum albumin as co-polymerized substrate, we identified a 28-kDa proteolytic activity released to the extracellular environment by mycelia of P. boydii. This peptidase was detected during the growth of P. boydii in Sabouraud-dextrose medium for 13 days and reached its maximal production on day 7. The 28-kDa peptidase was active in acidic pH (5.5) and had its activity completely blocked by 1,10-phenanthroline, a potent zinc-metallopeptidase inhibitor. Two other metallopeptidase inhibitors, EDTA and EGTA, were also tested and no alterations were observed in the activity of the 28-kDa extracellular peptidase. Likewise, E-64 (a cysteine peptidase inhibitor), phenylmethylsulphonyl fluoride (a serine peptidase inhibitor), and pepstatin A (an aspartyl peptidase inhibitor) did not significantly alter the enzymatic behavior. Collectively, we described for the first time the expression of an extracellular metallopeptidase in the human opportunistic fungal pathogen P. boydii.     

Pathogenicity of Alternaria alternata and Fusarium moniliforme and Phytotoxicity of AAL-toxin and Fumonisin B1 on Tomato Cultivars

Phytotoxicity of AAL-toxin and fumonisin B₁ to six cultivars of tomato was compared with the pathogenicity of their fungal sources, Alternaria alternata and Fusarium moniliforme, respectively. These include two AAL-toxin susceptible cultivars with genotypes(asc/asc), three resistant cultivars (Asc/Asc), and a heterozygous cultivar (Asc/asc.) A. alternata spores were pathogenic to the susceptible but not to the resistant cultivars F. moniliforme was not pathogenic to any of the tomatoes. Filtrates of both fungi grown on rice containing their respective toxins caused necrosis within 48 h and eventually mortality on susceptible cultivars but not on the resistant lines. The heterozygous cultivar Asc/asc showed minimal damage and no mortality after 14 days exposure to both filtrates and both toxins. The spores of both fungi had no effect on heterozygous intact plants. Tomato leaf disc bioassays with AAL-toxin and fumonisin B₁ at 1μM caused cellular leakage and reduced chlorophyll content in susceptible cultivars and minimal effects on the heterozygous and resistant varieties.     

Production of trichothecene and non-trichothecene mycotoxins by Fusarium species isolated from maize in Minnesota

Eighty-two cultures of Fusarium species isolated in 1986 from moldy maize in Minnesota were each cultured on rice for 4 weeks and found to produce the following mycotoxins: F. graminearum isolates, deoxynivalenol (DON, 4–225 g/g), 3-acetyldeoxynivalenol (3-ADON, 2–4g/g), 15-acetyldeoxynivalenol (15-ADON, 1–35 g/g) and zearalenone (ZEA, 5–4350 g/g); F. moniliforme, fusarin C (detectable amounts to 1000 g/g); F. mòniliforme, F. oxysporum, F. proliferatum and F. subglutinans isolates, moniliformin (15–6775 g/g); F. moniliforme, F. proliferatum, and F. subglutinans isolates, fusaric acid (detectable amounts). Other mycotoxins screened for in each rice sample and not detected were T-2 toxin, HT-2 toxin, neosolaniol, T-2 tetraol, nivalenol, fusarenon-X, scirpenols, alpha and beta trans-zearalenols, wortmannin, and fusarochromanone. The rat feeding bioassay indicated that other, unidentified toxins may be present.     

Contamination of freshly harvested maize kernels with<Emphasis Type="Underline">Fusarium</Emphasis> mycotoxins on Bihar state,India

Freshly harvested maize samples, collected from different fields of Bhagalpur during January-March, 1989, were analysed for the presence of Fusarium species and their toxins.F. moniliforme was most common followed byF. roseum,F. sporotrichioides,F. graminearum andF. equiseti. Different strains of these species produced zearalenone (11.2–28.2 μ/g), DON (0.3–2.9 μg/g) and T-2 (5.2–20.6 μg/g) toxins on mostrice medium. Fifteen per cent, out of 86 maize samples analysed, were found to be contaminated with various levels of above toxins, which occurred either alone or in groups. Toxin concentration in contaminated samples varied from 0.76–1.5 μg/g (ZEN), 0.41–202 μg/g (DON) and 0.55–2.92 μg/g (T-2).     

The inducible and cytochrome P450-containing dehydroepiandrosterone 7α-hydroxylating enzyme system of Fusarium moniliforme

7α-Hydroxylation of DHEA by Fusarium moniliforme was investigated with regard to inducibility and characterization of the responsible enzyme system. Using GC/MS, the 7-hydroxylated metabolites of DHEA produced after biotransformation by Fusarium moniliforme mycelia were identified. The strain of Fusarium moniliforme hydroxylated DHEA predominantly at the 7α-position, with minor hydroxylation occurring at the 7β-position. Constitutive 7α-hydroxylation activity was low, but DHEA induced the enzyme complex responsible for 7α-hydroxylation via an increase in protein synthesis. DHEA 7α-hydroxylase was found to be mainly microsomal, and the best production yields of 7α-hydroxy-DHEA (28.5 ± 3.51 pmol/min/mg protein) were obtained with microsomes prepared from 18-h-induced mycelia. Kinetic parameters (K_M=1.18 ± 0.035 μM and V_max=909 ± 27 pmol/min/mg protein) were determined. Carbon monoxide inhibited 7α-hydroxylation of DHEA by microsomes of Fusarium moniliforme. Also, exposure of mycelia to DHEA increased microsomal P450 content. These results demonstrated that: (i) DHEA is 7α-hydroxylated by microsomes of Fusarium moniliforme; (ii) DHEA induces Fusarium moniliforme 7α-hydroxylase; (iii) this enzyme complex contains a cytochrome P450.     

Subchronic toxicological investigations of Fusarium moniliforme-contaminated corn,culture material,and ammoniated culture material

The fungus Fusarium moniliforme is ubiquitous on corn throughout the world and is a likely co-contaminant on corn infested with aflatoxin-producing Aspergillus flavus. Ammoniation has been used to detoxify aflatoxin-contaminated commodities. To determine the effect of ammoniation on the toxic potential of Fusarium moniliforme, male Sprague-Dawley rats were fed either diets containing 10% sound corn, ammoniated corn, corn culture material of hepatotoxic F. moniliforme strain MRC 826 (CM), or ammoniated CM for four weeks. They were observed for signs of toxicity and hematological, serum chemical and histopathological evaluations were made. Groups of male Balb/c mice were fed diets fortified with 10% sound corn or CM for four weeks and evaluated by serum chemical and histopathological means to determine the suitability of mice as a model species for investigation of F. moniliforme-induced hepatotoxicity. Ammoniation was ineffective for detoxification of the CM. Hepatotoxicity and renal toxicity of CM and ammoniated CM were qualitatively similar, although renal tubular lesions appeared more advanced in rats fed ammoniated CM. Adrenal cortical cellular vacuolation was also found in CM and ammoniated CM-fed rats, while focal seminiferous tubular degeneration and aspermia were found only in the testes of ammoniated CM-fed rats. Fumonisin B₁ concentrations of the CM and ammoniated CM diets averaged 99 and 75 ppm, respectively. CM containing 99 ppm fumonisin B₁ also produced hepatotoxicity in mice similar to that found in CM-fed rats. Thus, mice may be useful for investigations of F. moniliforme-induced hepatotoxicity.Mention of a trademark, proprietary name or vendor does not imply its approval by the US Department of Agriculture to the exclusion of others that may also be suitable.     

Accumulation of cadmium and copper by the terrestrial snail Arianta arbustorum L.: kinetics and budgets

Summary Specimens of the terrestrial gastropod Arianta arbustorum were fed on cadmium- or copper-enriched agar plates with the aim of performing an input/output analysis and of studying the distribution of these metals in several organs of the snails. After a feeding period of 20 days about 45% of cadmium were lost. 36% accumulated in the hepatopancreas, where a cadmium concentration of more than 500 g/g was measured. The efficiency of cadmium assimilation decreased from about 90% at the beginning to about 55% after 20 days. Copper was distributed more evenly than cadmium, but the main site of copper storage seemed to be the foot/mantle tissues, where 49% of the ingested copper were found. The efficiency of copper assimilation always exceeded 95%. The patterns of distribution and assimilation of copper and cadmium are discussed in relation to differences in the cytological and biochemical detoxification mechanisms which exist for these metals in molluscs.     

Microbial transformation of ginsenoside Rb1 by Rhizopus stolonifer and Curvularia lunata

Of 49 microbial strains screened for their capabilities to transform ginsenoside Rb₁, Rhizopus stolonifer and Curvularia lunata produced four key metabolites: 3-O-[-d-glucopyranosyl-(1,2)--d-glucopyranosyl]- 20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ene (1), 3-O-[-d-glucopyranosyl-(1,2)--d- glucopyranosyl]-20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ol (2), 3-O-[-d-gluco- pyranosyl-(1,2)--d-glucopyranosyl]-3, 12, 20(S)-trihydroxydammar-24-ene (3), and 3-O--d-glucopyranosyl-3, 12, 20(S)-trihydroxydammar-24-ene (4), identified by TOF-MS, ¹H- and ¹³C-NMR spectral data. Metabolites 1, 3 and 4 were from the incubation with R. stolonifer, and 1 and 2 from the incubation with C. lunata. Compound 2 was identified as a new compound.     

Pulmonary pseudallescheriasis in a patient with healed tuberculosis

Pulmonary pseudallescheriasis in an immunocompetent patient without a pre-existing cavity or cyst is a rare phenomenon. We report a case of invasive pulmonary pseudallescheriasis in a lobectomised patient treated for tuberculosis. Filamentous fungi with pyriform conidia were seen in the bronchoalveolar lavage fluid .The fungus was identified as Pseudallescheria boydii on culture.     

Preharvest aflatoxin contamination of maize inoculated withAspergillus flavus andFusarium moniliforme

A two-year factorial experiment was utilized to test plants field-inoculated singly and in combination withAspergillus flavus andFusarium moniliforme. Pinbar inoculations were made through the husks with conidial suspensions, and 10-ear maize samples were harvested at 60 days post-silking for aflatoxin determinations. When ears were inoculated with both fungi simultaneously,F. moniliforme reduced aflatoxin formation byA. flavus isolate NRRL 3357 by approximately two-thirds.F. moniliforme had no significant effect on naturally occurring aflatoxin contamination byA. flavus. This may be due to the timing of infection by both fungi in the field. In nature,A. flavus andF. moniliforme respond differently to the environment, offering one explanation of whyF. moniliforme did not measurably affect the other fungus.     

Biological differences in reproductive strategy between the mosquito sibling species Anopheles gambiae sensu stricto and An. quadriannulatus

Females of the afrotropical mosquito species Anopheles gambiae Giles sensu stricto and An. quadriannulatus (Theobald) (Diptera: Culicidae) were studied for the effect of blood meal size and the frequency of blood feeding on reproductive development during the first gonotrophic cycle. To standardize the blood meals, meals were administered by enema in some experiments. The effects of insemination, mosquito size, and metabolic reserves at emergence on egg development were also investigated. Maximum insemination was reached after seven days, varying from 62% in An. quadriannulatus to 95% in An. gambiae and was significantly different (P<0.05) between the two species. Insemination had no effect on feeding success. Females of An. quadriannulatus were significantly larger than An. gambiae females (mean wing size 2.90 ±0.01 mm versus 2.82 ±0.01 mm), but the protein, glycogen, and lipid content of newly emerged females of the two species were not significantly different. Without a blood meal, larger females of both species were significantly more likely to develop oocytes up to Christopher's stage II. With one blood meal, 27% of An. gambiae became pre-gravid and 73% matured eggs. In contrast, all An. quadriannulatus females remained in the pre-gravid stage following ingestion of one blood meal. Vitellogenesis was significantly reduced in smaller-sized pre-gravid An. quadriannulatus compared to larger individuals. When given the opportunity to feed up to three times on three successive days, all females of An. gambiae matured eggs but only 85% of An. quadriannulatus did so. When 1 l of human blood was administered by enema, none of the females of either species developed eggs. With a single enema of 1.5 l of human blood, only An. gambiae developed eggs. A similar result was observed with 1 l and 1.5 l enemas of bovine blood although some An. gambiae also developed eggs with 1 l of blood. Anopheles quadriannulatus developed eggs only when given two 1 l enemas on successive days. However, the percentage of females developing eggs was significantly lower than that of An. gambiae. The implications of these differences in reproductive strategy are discussed in the light of behavioural traits in the field.