Erratum to: Antimicrobial resistance and virulence profile of enterococci isolated from poultry and cattle sources in Nigeria

Tropical Animal Health and Production -     

Involvement of the β-cinnamomin elicitin in infection and colonisation of cork oak roots by <Emphasis Type="Italic">Phytophthora cinnamomi</Emphasis>

The virulence of two wild type (PA45 and PA37) and two genetically modified (13C: hygromycin resistant; FATSS: hygromycin resistant and β-cin knock-down) Phytophthora cinnamomi strains towards cork oak (Quercus suber) was assessed via a quantitative evaluation of disease symptoms arising from a soil infestation assay, and by a histological analysis of root colonization. Comparison of virulence, as expressed by symptom severity, resulted in the following ranking: highly virulent (wild type strains), medium virulence (strain 13C) and weakly virulent (FATSS). Both transgenic strains were compromised in their virulence, as expressed by symptom severity, but strain 13C was much less affected than FATSS. Microscopic observation showed that the FATSS strain was unable to effectively invade the root, while 13C and the two wild type strains were all able to rapidly colonize the whole root, including the vascular tissue. These results strengthen the notion that elicitins are associated, either directly or indirectly, with the infection process of Phytophthora.     

Incidence and etiology of postharvest fungal diseases of loquat fruit (<Emphasis Type="Italic">Eriobotrya japonica</Emphasis> (Thunb.) Lindl. cv. ‘Algerie’) in Alacant province (Spain)

‘Algerie’ is currently the most important loquat cultivar in Spain. The incidence and etiology of postharvest diseases affecting this cultivar were determined under local conditions. Latent and wound pathogens were evaluated for two consecutive seasons on commercially grown loquats from two orchards. Healthy loquats were either surface-disinfected or artificially wounded in the rind and placed in humid chambers at 20 °C for up to 5 weeks. Additionally, decay was assessed on commercially-handled loquats stored at 5 °C for up to 20 weeks. The most frequent disease was caused by Alternaria alternata, followed by Penicillium expansum. These two pathogens were present on fruit assessed for all types of infection. Moreover, decay caused by Botrytis cinerea was abundantly observed on both wounded and cold-stored fruit, while Colletotrichum gloeosporioides was frequently found on surface-disinfected fruit. Other pathogens that were observed causing latent infection to a lesser extent included Pestalotiopsis clavispora and Diplodia seriata. Common isolates were identified by macroscopic and microscopic morphology and/or DNA amplification and sequencing. Pathogenicity of selected isolates was demonstrated by fulfilling Koch’s postulates and disease development was assessed on artificially inoculated loquats stored at either 20 or 5 °C.     

Low seed/nut productivity in cashew (Anacardium occidentale): Effects of self-incompatibility and honey bee (Apis mellifera) foraging behaviour

Summary

The roles of self- versus cross-pollination and honey bee (Apis mellifera L.) foraging behaviour in low nut yield of cashew (Anacardium occidentale L.) were studied in NE Brazil in 1997 and 1998. It was shown that both self- and cross-pollination can set fruits in cashew, but most of fruits originating from self-pollination are shed 9–15 d after pollination, and fruits harvested are primarily from cross-pollination. Honey bees display foraging behaviour in cashew orchards conducive to cross-pollination, but in plantations originating from clonal material they failed to increase fruit yield despite cashew's dependence on insect pollination. It is concluded that cashew has a mechanism of selective abortion through which it discards self-pollinated fruits and that honey bees can contribute to increased fruit yield only when cashew trees of genetically diverse origin are found in the same orchard.     

Characterization of exopolysaccharides produced by Bifidobacterium longum NB667 and its cholate-resistant derivative strain IPLA B667dCo

Bifidobacteria are natural members of the human intestinal microbiota and some strains are being used as probiotics. Adaptation to bile can allow them to increase survival in gastrointestinal conditions, thus improving their viability. Bifidobacterium longum NB667 and the cholate-resistant strain B. longum IPLA B667dCo produced exopolysaccharides (EPS) that were partially characterized. Analysis by size exclusion chromatography-multiangle laser light scattering indicated that the EPS crude fractions of both strains contained two polymer peaks of different molar mass. On the basis of chromatographic techniques both peaks appeared to be heteropolysaccharides. The smaller peak was mainly composed of glucose, galactose and rhamnose whose molar ratios and linkage types showed slight variations between the EPS fractions of both strains. The bigger peak consisted of glucose and galactose; the monosaccharide composition was identical in the EPS fractions of the two microorganisms, but their infrared spectra presented some differences regarding compounds other than carbohydrates that seem to be associated to the polymer. Differences in the composition of EPS fractions did not affect the capability of crude EPS from B. longum to be fermented by the human intestinal microbiota in fecal batch cultures.     

Isolation, structure characterization, and immunomodulating activity of a hyperbranched polysaccharide from the fruiting bodies of Ganoderma sinense

A polysaccharide (GSP-6B) with a molecular mass of 1.86 × 10? Da was isolated from the fruiting bodies of Ganoderma sinense . Chemical composition analysis, methylation analysis, infrared spectroscopy, and nuclear magnetic resonance spectroscopy were conducted to elucidate its structure. GSP-6B contains a backbone of (1→6)-linked-β-D-glucopyranosyl residues, bearing branches at the O-3 position of every two sugar residues along the backbone. The side chains contain (1→4)-linked-β-D-glucopyranosyl residues, (1→3)-linked-β-D-glucopyranosyl residues, and nonreducing end β-D-glucopyranosyl residues. An in vitro immunomodulating activity assay revealed that GSP-6B could significantly induce the release of IL-1β and TNF-α in human peripheral blood mononuclear cell (PBMC) and showed no toxicity to either PBMC or a human macrophage cell line THP-1. GSP-6B could also activate dendritic cells (DC) by stimulating the secretion of IL-12 and IL-10 from DC.     

New Bruce-ladder multiplex PCR assay for the biovar typing of Brucella suis and the discrimination of Brucella suis and Brucella canis

Rapid and specific identification of Brucella suis at the biovar level is necessary because some of the biovars that infect animals are pathogenic for humans. None of the molecular typing methods described so far are able to discriminate B. suis biovars in a single test and differentiation of B. suis from Brucella canis by molecular approaches can be difficult. This article describes a new multiplex PCR assay, Suis-ladder, for fast and accurate identification of B. suis at the biovar level and the differentiation of B. suis, B. canis and Brucella microti. An advancement of the original Bruce-ladder PCR protocol which allows the correct discrimination of all known Brucella species is also described.     

Growth and Physiological Responses of Triticum aestivum and Deschampsia caespitosa Exposed to Petroleum Coke

Methylibium petroleiphilum PM1, which is capable of degrading of methyl tert-butyl ether (MTBE), was immobilized in calcium alginate gel beads. Various applications were explored to increase the mechanical strength of these gel beads. The introduction of 0.3 mol/L calcium chloride into the crosslinking solution, 0.002 mol/L calcium chloride into the growth medium, and 0.2% polyethyleneimine (PEI) as chemical crosslinking agent increased the stability of the Ca-alginate gel beads under the operation conditions of the bioreactor. The degradation rates of MTBE by the immobilized cells in the bioreactor system operated in batch and continuous mode , respectively, were compared. A MTBE biodegradation rate of 5.79 mg/L·h was reached for over 400 h (50 batches), and the immobilized cells in the bioreactor removed >96% MTBE during 50 days of operation. Molecular analysis of the PM1 cells revealed that microbial growth occurred predominantly as microcolonies in the outer area of the beads during the first 20 days of operation. The results of this study show that a continuous-mode, fixed-bed bioreactor reactor coupled with PM1-immobilized cells is a promising technology for remediating MTBE-contaminated groundwater.     

Cadmium Effects in Sunflower: Nutritional Imbalances in Plants and Calluses

The effects of cadmium (Cd) exposure on sunflower (Helianthus annuus L.) nutrient accumulation remain unclear. However, studies concerning crop improvement for Cd tolerance suggest the use of biotechnology techniques such as tissue culture. It is still unknown whether in vitro cells respond to Cd exposure in a way similar to plants. In this paper, the objectives were (1) to characterize the effects of Cd exposure in macronutrient and micronutrient accumulation in different sunflower organs/tissues and (2) to compare the behavior of two culture systems (plants vs. tissue culture) regarding Cd and nutrient accumulation. To achieve these aims, sunflower plants were grown hydroponically in the presence of Cd (at levels of 0, 5, 50, and 500 μ M). For in vitro cultures, seeds were germinated axenically and leaf explants were then grown on Murashige and Skoog medium (MS). One-month-old calluses were grown on MS medium containing 0, 5, 50, and 500 μ M Cd. After 21 d of exposure to 500 μ M, all plants were dead. The contents of macro- and micronutrients and of Cd were determined by ICPS in 18 d-exposed plants and calluses and in calluses exposed for six months to 50 μ M Cd. At day 18, Cd content increased in leaves, roots, and calluses. Cadmium exposure also decreased the contents of magnesium (Mg), calcium (Ca), iron (Fe), and manganese (Mn) in roots and of Mg, Ca, copper (Cu), Fe, and Mn in shoots. Exposed calluses suffered decreases only in Mg, Ca, and Mn contents. The contents of most of these nutrients in six-month-exposed calluses were similar to those of the control calluses, indicating that these long-term exposed in vitro cells developed mechanisms for regulating the effects of Cd on the accumulation of nutrients.     

Assessment of latent infection frequency in progeny tubers of advanced potatoclones resistant to bacterial wilt: A new selection criterion

Summary This paper reports results of a 3-year evaluation of CIP advanced potato clones in a bacterial wilt-infested field (race 3) in Peru. Clones resistant or moderately resistant to wilt were selected and all tubers harvested from each clone were tested for latent infection byRalstonia solanacearum using a sensitive serological technique developed at CIP. A sampling strategy to estimate accurately the frequency of infected tubers in the clones has been evaluated. This method will allow consideration of tuber latent infection as a new selection criterion in breeding for resistance to bacterial wilt. Thirteen clones were found resistant to wilt in all three evaluations (i.e.≤6% wilt), from which five had no wilt in all trials. However, all clones harboured latent infection in tubers averaging 30%. Analysing 30 tubers/clone provides an accurate estimation of the proportion of infected tubers with a high precision level.