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991.
Luis A. Garay Irnayuli R. Sitepu Tomas Cajka Jian Xu Hui Ean Teh J. Bruce German Zhongli Pan Stephanie R. Dungan David E. Block Kyria L. Boundy-Mills 《Biotechnology advances》2018,36(2):397-414
Extracellular fungal glycolipid biosurfactants have attracted attention because productivities can be high, cheap substrates can be used, the molecules are secreted into the medium and the downstream processing is relatively simple. Three classes of extracellular fungal glycolipid biosurfactants have provided most of the scientific advances in this area, namely sophorolipids, mannosylerythritol lipids and cellobioselipids. Polyol lipids, a fourth class of extracellular fungal glycolipid biosurfactants, comprise two groups of molecules: liamocins produced by the yeast-like fungus Aureobasidium pullulans, and polyol esters of fatty acids, produced by some Rhodotorula yeast species. Both are amphiphilic, surface active molecules with potential for commercial development as surfactants for industrial and household applications. The current knowledge of polyol lipids highlights an emerging group of extracellular fungal glycolipid biosurfactants and provides a perspective of what next steps are needed to harness the benefits and applications of this novel group of molecules. 相似文献
992.
Fungi are well known for their metabolic versatility, whether it is the degradation of complex organic substrates or the biosynthesis of intricate secondary metabolites. The vast majority of studies concerning fungal metabolic pathways for sulfur assimilation have focused on conventional sources of sulfur such as inorganic sulfur ions and sulfur-containing biomolecules. Less is known about the metabolic pathways involved in the assimilation of so-called “alternative” sulfur sources such as sulfides, sulfoxides, sulfones, sulfonates, sulfate esters and sulfamates. This review summarizes our current knowledge regarding the structural diversity of sulfur compounds assimilated by fungi as well as the biochemistry and genetics of metabolic pathways involved in this process. Shared sequence homology between bacterial and fungal sulfur assimilation genes have lead to the identification of several candidate genes in fungi while other enzyme activities and pathways so far appear to be specific to the fungal kingdom. Increased knowledge of how fungi catabolize this group of compounds will ultimately contribute to a more complete understanding of sulfur cycling in nature as well as the environmental fate of sulfur-containing xenobiotics. 相似文献
993.
Shyam Gopalakrishnan Mikkel-Holger S. Sinding Jazmín Ramos-Madrigal Jonas Niemann Jose A. Samaniego Castruita Filipe G. Vieira Christian Carøe Marc de Manuel Montero Lukas Kuderna Aitor Serres Víctor Manuel González-Basallote Yan-Hu Liu Guo-Dong Wang Tomas Marques-Bonet Siavash Mirarab Carlos Fernandes Philippe Gaubert Klaus-Peter Koepfli M. Thomas P. Gilbert 《Current biology : CB》2018,28(21):3441-3449.e5
994.
Torbjörn Tyler Fia Bengtsson Carl Johan Dahlberg Niklas Lönnell Tomas Hallingbäck Triin Reitalu 《Journal of bryology》2018,40(1):12-30
Factors driving the species richness and distribution of bryophytes are poorly studied and not well understood, particularly in grasslands. We analysed the occurrence of bryophyte species and variation in species richness across 674 plots (0.5?m?×?0.5?m) in alvar vegetation (grassland on limestone pavement with thin or no soil) on Öland (Sweden) in relation to substrate characteristics and chemistry, inundation frequency, grazing pressure and geographical variables. We found 148 taxa, including 11 nationally red-listed ones. Species richness per plot was significantly associated with substrate type, positively associated with pH and grazing intensity, but negatively associated with soil depth. However, richness of species typical of, or restricted to, alvar habitats responded differently to richness of species more common in other habitats. Typical alvar species were favoured by high pH, shallow soil and low phosphate availability, while generalists preferred relatively low pH, higher phosphate availability and organic or mull soil types. Distance from the alvar margin had only weak effects. Concerning the effects on individual species and community composition, inundation frequency and pH were found to have the largest effects, although other factors (substrate type, soil depth, bare soil, bare stone, phosphate availability and grazing pressure) were more important for some individual species, stressing the importance of microsite variability and variability in management for regional species richness. From a conservation perspective, it is concluded that grazing is generally positive whilst factors increasing phosphate availability may disadvantage the typical alvar species, and proximity to the alvar margin is not a major problem. 相似文献
995.
996.
PM2 is an Aeromonas-specific bacteriophage isolated on A. hydrophila strain AH-3. The bacteriophage receptor for this phage was found to be the lipopolysaccharide (LPS), specifically a low-molecular weight LPS fraction (LPS-core oligosaccharides). Mutants resistant to this phage were isolated and found to be devoid of LPS O-antigen and altered in the LPS-core. No other outer-membrane (OM) molecules appeared to be involved in phage binding. 相似文献
997.
Uptake and utilization of nitrate were investigated in Hordeum vulgare L. cvs Mette and Golf in the vegetative stage, 2 and 4 weeks after sowing. The plants were subjected to a light/dark cycle of 16/8 h (18/12°C). Results obtained with the two genotypes were essentially similar. In the light, xylem nitrate transport and shoot nitrate reduction approximately equalled the amount of nitrate absorbed by the root. A drastic decline in translocation to the shoot in darkness was entirely attributable to decreased transpiration since no major changes in xylem nitrate concentration were observed. Darkening caused only a slight decrease in nitrate uptake, while root nitrate reduction was enhanced. Nitrate starvation for 2 days did not significantlly affect dry matter increment, but resulted in a drastic drop in previously accumulated nitrate, indicating that the stored nitrate is accessible and can sustain unrestricted growth. Uptake increased upon re-addition of nitrate and after 8 h it was about twice that of non-starved plants. During recovery, restoration of root nitrate pools and root nitrate reduction took precedence over shoot nitrate accumulation and reduction. Net nitrate uptake and removal of nitrate from the root to the transpiration stream seem to be decisive for the rate of root nitrate reduction. 相似文献
998.
999.
Jitka Kasparovska Martina Pecinkova Katerina Dadakova Ludmila Krizova Sylvie Hadrova Matej Lexa Jan Lochman Tomas Kasparovsky 《PloS one》2016,11(4)
In this study, we compared the effects of two diets containing different isoflavone concentrations on the isoflavone transfer from feed into milk and on the rumen microbiota in lactating dairy cows. The on-farm experiment was conducted on twelve lactating Czech Fleckvieh x Holstein cows divided into two groups, each with similar mean milk yield. Twice daily, cows were individually fed a diet based on maize silage, meadow hay and supplemental mixture. Control group (CTRL) received the basal diet while the experimental group (EXP) received the basal diet supplemented with 40% soybean isoflavone extract. The average daily isoflavone intake in the EXP group (16 g/day) was twice as high as that in the CTRL group (8.4 g/day, P<0.001). Total isoflavone concentrations in milk from the CTRL and EXP groups were 96.89 and 276.07 μg/L, respectively (P<0.001). Equol concentrations in milk increased from 77.78 μg/L in the CTRL group to 186.30 μg/L in the EXP group (P<0.001). The V3-4 region of bacterial 16S rRNA genes was used for metagenomic analysis of the rumen microbiome. The experimental cows exhibited fewer OTUs at a distance level of 0.03 compared to control cows (P<0.05) and reduced microbial richness compared to control cows based on the calculated Inverse Simpson and Shannon indices. Non-metric multidimensional scaling analysis showed that the major contributor to separation between the experimental and control groups were changes in the representation of bacteria belonging to the phyla Bacteroidetes, Proteobacteria, Firmicutes, and Planctomycetes. Surprisingly, a statistically significant positive correlation was found only between isoflavones and the phyla Burkholderiales (r = 0.65, P<0.05) and unclassified Betaproteobacteria (r = 0.58, P<0.05). Previous mouse and human studies of isoflavone effects on the composition of gastrointestinal microbial populations generally report similar findings. 相似文献
1000.