Enrique Hernández

Determination of trichothecenes, zearalenone and zearalenols in commercially available corn-based foods in Spain

Among the main Spanish commercially available trademarks, we have selected a total of 25 samples of corn-based foods, which have the highest consume rate, to carry out the analysis of deoxynivalenol (DON), T-2 toxin, zearalenone (ZEA) and zearalenols (ZOL). The contents of mycotoxins were determined by gas chromatography with flame ionization detection, and those of ZEA were confirmed by HPLC with fluorescence detection. Of the 25 analyzed samples, the incidence of DON, ZEA and alfa-ZOL was 68, 44 and 24%, respectively; levels detected ranged from 29-195, 34-216, and 36-71 microg/kg, respectively. T-2 toxin was only detected in one sample (<50 microg/kg). Beta-ZOL was not present in excess of the detection limit in the investigated samples. The results suggest a risk for consumers of corn products and the need to monitor the final products before consumption. This is the first report in Spain on natural contamination with these mycotoxins in corn-based foods.

Note. In Vitro Viability of Bifidobacterium Strains Isolated from Commercial Dairy Products Exposed to Human Gastrointestinal Conditions

Levels of bifidobacteria contained in commercial fermented milks in Spain were determined by fluorescent techniques. The transit tolerance of probiotic bifidobacteria strains to human gastrointestinal tract (GIT) was assessed in vitro. The number of bifidobacteria in commercial fermented milks declared to contain bifidobacteria varied from 104 to 107 bacteria/m L. Viable cell counts estimated by plating onto selective media were lower than direct counts. Bifidobacteriumstrains analysed showed different survival behaviour. Viable bacteria counts decreased considerably following exposure to gastric juice. As only intrinsic acid resistant cells survive their passage through the human intestine, the selection of acid tolerant strains is necessary for the elaboration of probiotic products. Viability of dairy bifidobacteria is affected by gastrointestinal juices but the majority of tested strains survived well at gastrointestinal conditions. The reason for this may be the low number of viable bifidobacteria contained in commercial dairy products. Adaptation and survival at low pH is likely to determine the efficacy of Bifidobacterium strains both as dairy starters and probiotic microorganisms. This study confirmed the usefulness of fluorescent techniques for a rapid and accurate evaluation of bacterial viability in probiotic products.

Detection of fusarin C and trichothecenes in Fusarium strains from Spain

A group of 49 strains of Fusarium sp. isolated from different Spanish samples of cereals and mixed feedstuffs were screened for their ability to produce trichothecenes like T‐2 toxin (T‐2), HT‐2 toxin (HT‐2), diacetoxyscirpenol (DAS) and deoxynivalenol (DN), as well as other mycotoxin produced by Fusarium named fusarin C. The production of these mycotoxins was analyzed by means of spectro‐photometry, thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and gas chromatography (GC). Results showed that from 19 Fusarium strains in which cultures trichothe‐cene production was detected, 15 were HT‐2 producers, 9 T‐2 producers, 14 DAS producers and 10 DN producers. On the other hand, from 28 Fusarium strains in which cultures fusarin C production was detected, 22 were low fusarin C producers (ranged from 0.04 to 1 μg/l ICI medium), 5 Fusarium strains were intermediate‐level producers (ranged from 1 to 10 μg/l ICI medium) and one Fusarium strain produced 240 μg/l ICI medium. The identified Fusarium strains that produced trichothecenes and fusarin C were F. moniliforme and F. oxysporum.

A new approach to optimize bandwidth reservation for real-time video transmission with deterministic guarantees

The transmission of video requires new service models for providing quality of service (QoS). Some of these models are based on resource reservation and admission control while others rely on resource provisioning. In both approaches, optimally estimating the resource requirements of a given video is a key issue, since they are always very demanding. This paper introduces a fast and bounded method to optimize the required network resources (bandwidth) to guarantee a maximum deterministic delay for a given workload and network state. The method is based on characterizing the workload of a stored video using a reduced set of points obtained from an off-line analysis of its empirical envelope. The paper also proposes the above workload characterization to perform the admission control test using a WFQ scheduler. The evaluation of this scheme shows that it can achieve an utilization higher than a 50% for a single flow with a 1-s deadline and reach up to an 80% with a 5-s delay. Results are also compared to tests based on EDF schemes, which have been proved to be optimal with one node. It is shown that the proposed scheme is a little less efficient than the optimal EDF scheduler with one node (as expected), but it is practically as efficient (or even better with a moderately high number of nodes) than the best known RC-EDF policies with several nodes. This is an interesting result because it shows that the WFQ schedulers can achieve a similar efficiency to EDF schedulers avoiding the complexity of their admission control tests.The transmission of video requires new service models for providing quality of service (QoS). Some of these models are based on resource reservation and admission control while others rely on resource provisioning. In both approaches, optimally estimating the resource requirements of a given video is a key issue, since they are always very demanding. This paper introduces a fast and bounded method to optimize the required network resources (bandwidth) to guarantee a maximum deterministic delay for a given workload and network state. The method is based on characterizing the workload of a stored video using a reduced set of points obtained from an off-line analysis of its empirical envelope. The paper also proposes the above workload characterization to perform the admission control test using a WFQ scheduler. The evaluation of this scheme shows that it can achieve an utilization higher than a 50% for a single flow with a 1-s deadline and reach up to an 80% with a 5-s delay. Results are also compared to tests based on EDF schemes, which have been proved to be optimal with one node. It is shown that the proposed scheme is a little less efficient than the optimal EDF scheduler with one node (as expected), but it is practically as efficient (or even better with a moderately high number of nodes) than the best known RC-EDF policies with several nodes. This is an interesting result because it shows that the WFQ schedulers can achieve a similar efficiency to EDF schedulers avoiding the complexity of their admission control tests. r 2002 Elsevier Science Ltd. All rights reserved.

Isolation and identification of ethisolide as an antibiotic product from Penicillium capsulatum.

SummaryEthisolide has been isolated from cultures of Penicillium capsulatum, and its structure determined by means of infrared, mass spectrometry, 1H- and 13C nuclear magnetic resonance. Antibiotic activity against a number of microorganisms is reported.

Mobile Pollution Data Sensing Using UAVs

Nowadays, the impact of global warming is causing societies to become more aware and responsive to environmental problems. As a result, pollution sensing is gaining more relevance. In order to have a strict control over air quality, the use of mobile sensors is becoming a promising alternative to traditional air quality stations. Mobile sensors allow to easily perform measurements in many different places, thereby offering substantial improvements in terms of the spatial granularity of the data gathered. Pollution monitoring near large industrial areas or in rural areas where transportation facilities are poor or inexistent can complicate the mobile sensing approach. To address this problem, in this paper we propose endowing Unmanned Aerial Vehicles (UAVs) with pollution sensors, allowing them to become autonomous air monitoring stations. The proposed solution has the potential to quickly cover a target region at a low cost, and providing great flexibility.

Bioproduction of an extract from Penicillium funiculosum Thom with activity against Ceratitis capitata and Tetranychus urticae

The bioproduction conditions of a crude extract from a strain of Penicillium funiculosum Thom, which shows activity against Ceratitis capitata and Tetranychus urticae, have been optimized. The efficacy degree was 95% (C. capitata) and 100% (T. urticae), according to Abbot. This is the first report on the pesticide activity of an extract from P. funiculosum against these species. The best yields were obtained when P. funiculosum was grown in Raulin-Thom medium at pH 6.5 with sucrose candy as the carbon source and ammonium sulphate and phosphate as the nitrogen source. Other favourable conditions were static cultures, at 28°C, and in the dark.

Fusarin C production by Fusarium spp. from Spain

From 657 samples of grains and feedstuffs (1991 to 1992 and 1992 to 1993 surveys), collected in two different geographical areas of Spain, 154 isolates of Fusarium spp. were obtained. The isolates were screened for their ability to produce fusarin C in a modified 10% ICI N synthetic liquid medium. The production of fusarin C was verified by means of spectrophotometry, thin layer chromatography, high-performance liquid chromatography, and nuclear magnetic resonance. Results showed that more than 57% of tested isolates were able to produce fusarin C at levels of 0.04 to 200 μg/liter of ICI medium. There were no statistically significant differences (P < 0.05) between levels of fusarin C production and the geographical origin of the Fusarium isolates. The Fusarium isolates that produced fusarin C were identified as F. moniliforme , F. oxysporum , F. sporotrichioides , and F. poae . This is the first report of fusarin C production by F. oxysporum .

Relationship between the stages of development of Fusarium moniliforme ATCC 38932 and production of fusarin C

A study of the kinetics of fusarin C production by Fusarium moniliforme ATCC 38932, a known producer of fusarin C, was carried out. This strain was subcultured on an EG medium for an adequate sporulation, and a 4% inoculum was transferred to the 10% ICI N medium. The conditions for the production of fusarin C in this synthetic culture medium were optimized. The time-course study of fusarin C performed over 26 days with this strain showed three different developmental stages in which a maximum production of fusarin C was reached on the 8th day of incubation; thereafter this strain ceased growing exponentially and exhibited a sharp decrease of fusarin C from that moment on.