嗜热子囊菌利用短链有机酸生产角质酶

以嗜热子囊菌(Thermobifida fusca WSH03-11)发酵生产角质酶为模型,研究微生物利用市政污泥厌氧酸化所产短链有机酸为碳源发酵生产高附加值产品的可能。发现：(1)以丁酸、丙酸和乙酸为碳源时,有机酸和氮元素浓度分别为8.0 g/L和1.5 g/L有利于角质酶的生产;而以乳酸为碳源时,最适有机酸和氮源浓度分别为3.0 g/L和1.0 g/L;(2)改变诱导物角质的浓度,以丁酸、丙酸、乙酸和乳酸为碳源,分别比优化前提高了31.0%、13.3%、43.8%和73.2%;(3)在四种有机酸中,T. fusca WSH03-11利用乙酸的速率最快,平均比消耗速率是丙酸的1.3倍,丁酸的2.0倍及乳酸的2.2倍;以丁酸为碳源时的酶活(52.4 U/mL)是乳酸的1.7倍、乙酸的2.5倍和丙酸的3.2倍;角质酶对乳酸的得率(12.70 u/mg)分别是丁酸的1.4倍、丙酸的3.0倍和乙酸的3.8倍;(4)以混合酸为碳源生产角质酶,T. fusca WSH03-11优先利用乙酸,而对丁酸的利用受到抑制。进一步研究发现,混合酸中0.5 g/L的乙酸将导致丁酸的消耗量降低66.7%。这是首次利用混合酸作碳源发酵生产角质酶的研究报道。这一研究结果进一步确证了利用市政污泥厌氧酸化所产有机酸为碳源发酵生产高附加值产品的可行性,为以廉价碳源生产角质酶奠定了良好的基础。     

Earthquake impacts in old‐growth Nothofagus forests in New Zealand

Abstract. Six stands located on different land forms in mixed old‐growth Nothofagus forests in the Matiri Valley (northwest of South Island, New Zealand) were sampled to examine the effects of two recent large earthquakes on tree establishment and tree‐ring growth, and how these varied across land forms. 50 trees were cored in each stand to determine age structure and the cores were cross‐dated to precisely date unusual periods of radial growth. The 1968 earthquake (M = 7.1, epicentre 35 km from the study area) had no discernible impact on the sampled stands. The impact of the 1929 earthquake (M = 7.7, epicentre 20 km from the study area) varied between stands, depending on whether or not they had been damaged by soil or rock movement. In all stands, the age structures showed a pulse of N. fusca establishment following the 1929 earthquake, with this species dominating establishment in large gaps created by landslides. Smaller gaps, created by branch or tree death, were closed by both N. fusca and N. menziesii. The long period of releases (1929–1945) indicates that direct earthquake damage was not the only cause of tree death, and that many trees died subsequently most likely of pathogen attack or a drought in the early 1930s. The impacts of the 1929 earthquake are compared to a storm in 1905 and a drought in 1974–1978 which also affected forests in the region. Our results confirm that earthquakes are an important factor driving forest dynamics in this tectonically active region, and that the diversity of earthquake impacts is a major source of heterogeneity in forest structure and regeneration.     

Cloning, expression and identification of a new trehalose synthase gene from Thermobifida fusca genome

Trehalose is a disaccharide with two glucose mole-cules linked in an α,α-1,1-glycosidic linkage. The onlyreducing group in each of its glucose molecules has beenused up for the formation of α,α-1,1-glycosidic linkage,therefore trehalose is a nonreducing disaccharide withhigh stability against the disruption caused by such factorsas temperature and extreme pH of environment [1]. Ithas been well established that many organisms will copewith external stress conditions by increasing the levelo…     

The impact of environmental perturbation on microbial community structure and dynamics: Factors affecting growth of Clonothrix fusca in groundwater

Abstract

In a previous work temporal succession of two sheathed, filamentous methanotrophic γ-Proteobacteria, Crenothrix polyspora and Clonothrix fusca, was observed by analyzing the microbial community of an artesian well. Although a correlation between physical-chemical environmental parameters and growth of these microorganisms was suggested, the link with the microbial physiology remained elusive. In this study we demonstrate that phosphatidylethanolamine and cardiolipin, generally abundant in most γ-Proteobacteria, could not be detected in C. fusca membranes by thin-layer chromatography. The absence of cardiolipin was supported by results of enzymatic assay of cardiolipin synthase activity and by Southern blot analysis that failed to detect cls homologous sequences in the genomic DNA of this microorganism. The absence of phosphatidylethanolamine and cardiolipin might account for requirement of millimolar concentrations of magnesium and calcium for growth, and for massive over-growth of this microorganism during the winter season when the water levels of magnesium and calcium increased in the artesian well.     

Characterization of eight microsatellite loci in the maize stalk borer Busseola fusca Fuller, 1901 (Lepidoptera: Noctuidae)

The noctuid stem borer Busseola fusca occurs throughout sub‐Saharan Africa, where it is considered as a major pest of corn and sorghum. To understand B. fusca phylogeography, we isolated and characterized eight microsatellite loci in this species. We investigated these loci for polymorphism on a subset sample of individuals from different geographic populations. All loci were polymorphic, showing between four and 10 alleles. Cross‐species amplification of four of these loci was tested on 11 other noctuid species.     

嗜热子囊菌利用短链有机酸生产角质酶

以嗜热子囊菌(Thermobifida fusca WSH03-11)发酵生产角质酶为模型,研究微生物利用市政污泥厌氧酸化所产短链有机酸为碳源发酵生产高附加值产品的可能。发现：(1)以丁酸、丙酸和乙酸为碳源时,有机酸和氮元素浓度分别为8.0 g/L和1.5 g/L有利于角质酶的生产;而以乳酸为碳源时,最适有机酸和氮源浓度分别为3.0 g/L和1.0 g/L;(2)改变诱导物角质的浓度,以丁酸、丙酸、乙酸和乳酸为碳源,分别比优化前提高了31.0%、13.3%、43.8%和73.2%;(3)在四种有机酸中,T. fusca WSH03-11利用乙酸的速率最快,平均比消耗速率是丙酸的1.3倍,丁酸的2.0倍及乳酸的2.2倍;以丁酸为碳源时的酶活(52.4 U/mL)是乳酸的1.7倍、乙酸的2.5倍和丙酸的3.2倍;角质酶对乳酸的得率(12.70 u/mg)分别是丁酸的1.4倍、丙酸的3.0倍和乙酸的3.8倍;(4)以混合酸为碳源生产角质酶,T. fusca WSH03-11优先利用乙酸,而对丁酸的利用受到抑制。进一步研究发现,混合酸中0.5 g/L的乙酸将导致丁酸的消耗量降低66.7%。这是首次利用混合酸作碳源发酵生产角质酶的研究报道。这一研究结果进一步确证了利用市政污泥厌氧酸化所产有机酸为碳源发酵生产高附加值产品的可行性,为以廉价碳源生产角质酶奠定了良好的基础。     

Calyx fluid proteins of two Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) biotypes in Kenya: implications to biological control of the stem borer Busseola fusca (Fuller) (Lepidoptera: Noctuidae)

Cotesia sesamiae (Cameron) (Hymenoptera: Braconidae) is an indigenous larval endoparasitoid of Busseola fusca (Fuller) (Lepidoptera: Noctuidae) in sub-Saharan Africa. In Kenya, reports suggest that C. sesamiae occurs as two biotypes. Biotype avirulent to B. fusca gets encapsulated by haemocytes in this host and is unable to complete development. Biotype virulent to B. fusca is able to overcome immune defences. Factors present in the calyx fluid such as the PolyDNAviruses (PDV), venom and calyx fluid proteins have been implicated in the variation of C. sesamiae virulence against B. fusca. In the present study, calyx fluid proteins of the two C. sesamiae biotypes were compared using 2-D gel electrophoresis. More protein spots were observed in the virulent parasitoid calyx fluid, but some proteins were specifically observed in the avirulent parasitoid calyx fluid while others were observed in both. To study changes in proteins due to parasitism of B. fusca larvae by the two strains, SDS-PAGE gel were performed on fat body tissues and the haemolymph at three time points. Differences between the two strains were observed in both the fat body and haemolymph tissues. Parasitism-specific protein bands were detectable in fat body tissues of B. fusca larvae parasitized by the two C. sesamiae strains. These proteins were absent in unparasitized larvae. Implications for using C. sesamiae as a biocontrol agent of B. fusca in Africa are discussed.     

Vertical stratification in the spatial distribution of the beech scale insect (Ultracoelostoma assimile) in Nothofagus tree canopies in New Zealand

Abstract. 1. The degree of infestation by New Zealand sooty beech scale insects (Ultracoelostoma assimile, Homoptera: Margarodidae) varies dramatically among adjacent southern beech trees (Nothofagus spp., Fagaceae), but has previously been assumed to be uniformly or randomly distributed within individual host trees. In this study, a full‐census survey was conducted from ground level to canopy level on 14 naturally occurring, canopy‐dominant red beech (Nothofagus fusca) trees (size range 38.7–107.6 cm diameter at breast height) to determine the degree of within‐tree heterogeneity in herbivore density. 2. The within‐tree distribution of the sooty beech scale was vertically stratified and highly heterogeneous, with the greatest densities occurring on bark surfaces in the canopy rather than on the trunk, and on the lower rather than upper sides of the branches. The spatial distribution was strongly negatively correlated with trunk and branch diameter, and increasing bark thickness (as a function of diameter) provides a plausible explanation for differences in the establishment and population density of sooty beech scale insects with trunk and branch size. Furthermore, there was a significant change in the spatial distribution of scale insect populations on trunks and branches of trees of increasing diameter at breast height. This indicates a strong temporal component to the spatial dynamics of the sooty beech scale insect driven by changing host phenology. Future studies on phytophagous insects infesting large host trees need to consider more explicitly changes in population dynamics through space and time. 3. Because of the high degree of within‐tree heterogeneity in population density, the total population size of scale insects on an individual tree could not be predicted from any measure of population density low on the trunk. However, the dry weight biomass of sooty mould fungi growing on the ground beneath infested trees was a remarkably accurate predictor of the total population size of scale insects. The use of sooty mould fungi as a relative measure of population size could be incorporated into studies of other honeydew‐producing hemipterans, since the growth of sooty mould is a distinctive feature synonymous with high concentrations of honeydew production worldwide.