Metabolomic change and pathway profiling reveal enhanced ansamitocin P-3 production in Actinosynnema pretiosum with low organic nitrogen availability in culture medium

2020 ◽  
Vol 104 (8) ◽  
pp. 3555-3568
Author(s):  
Ting Liu ◽  
Linbing Yang ◽  
Jun Chen ◽  
Fengxian Hu ◽  
Liu-Jing Wei ◽  
...  
Keyword(s):  
Organic Nitrogen ◽  
Culture Medium ◽  
Nitrogen Availability ◽  
Actinosynnema Pretiosum

The in Vitro Culture of Excised Ovules from Velvetleaf (Abutilon theophrasti)

Weed Science ◽  
1984 ◽  
Vol 32 (6) ◽  
pp. 792-797 ◽  
Author(s):  
Laura K. Thompson ◽  
Gerald R. Leather ◽  
Maynard G. Hale
Keyword(s):  
Organic Nitrogen ◽  
Culture Medium ◽  
Green Light ◽  
Abutilon Theophrasti ◽  
Ovule Development ◽  
Nutrient Media ◽  
Organic Nitrogen Source ◽  
Embryo Length

A culture medium and environmental conditions were selected for ovule culture of velvetleaf (Abutilon theophrasti Medic. ♯4 ABUTH), which allowed development parallel to that occurring in vivo. Of the six nutrient media evaluated, the most suitable one contained an organic nitrogen source and was of high osmotic potential. A liquid medium with a pH of 5 to 7, and culture for 14 days at 25 C under green light (1.3 μmole·m-2·-1) encouraged good embryo and ovule development. No difference was recorded between polyethylene glycol 20000 and mannitol in the medium used for dehydration and subsequent imbibition of cultured mature ovules. To investigate the effects of maternal tissues, surgical alterations were performed on the testa and funiculus of immature velvetleaf ovules. The intact testa appears to be a barrier to nutrient absorption and reduces the fresh and dry weights and embryo length. Ovule and embryo development was significantly better if either the testa was nicked or the funiculus removed.

scholarly journals Measuring ecosystem nitrogen status: a comparison of proxies

2016 ◽  
Author(s):  
Maya Almaraz ◽  
Stephen Porder
Keyword(s):  
N Mineralization ◽  
Organic Nitrogen ◽  
Nitrogen Availability ◽  
N Availability ◽  
Net N Mineralization ◽  
Net Nitrification ◽  
Soil Δ15n ◽  
Foliar Δ15n ◽  
N Status

Abstract. There are many proxies used to measure nitrogen (N) availability in watersheds, but the degree to which they do (or do not correlate) within a watershed has not been systematically addressed. We surveyed the literature for intact forest or grassland watersheds in which several metrics of nitrogen availability have been measured. Our metrics included: foliar δ15N, soil δ15N, net nitrification, net N mineralization, and the ratio of dissolved inorganic to organic nitrogen (DIN : DON) in soil solution and streams. Not surprisingly, the strongest correlation (Kendall's tau) was between net nitrification and N mineralization (τ = 0.61, p < 0.0001). Net nitrification was correlated with foliar and soil δ15N (p < 0.05), while net N mineralization was correlated with soil δ15N but not foliar δ15N. Foliar and soil δ15N were correlated across tropical sites (τ = 0.68, p < 0.0001), but not in temperate sites (τ = 0.02, p > 0.05). To our surprise, the only significant correlation we found between terrestrial- and water-based metrics was that of net N mineralization with stream DIN : DON (τ = 0.62, p = 0.004). Given both soil δ15N and stream DIN : DON are used to infer long-term N status, their lack of correlation in watersheds merits further investigation.

MICROBIOLOGICAL DEGRADATION OF QUERCITRIN

1963 ◽  
Vol 9 (2) ◽  
pp. 211-220 ◽  
Author(s):  
D. W. S. Westlake
Keyword(s):  
Carbon Monoxide ◽  
Carboxylic Acid ◽  
Aspergillus Flavus ◽  
Yeast Extract ◽  
Organic Nitrogen ◽  
Culture Medium ◽  
Alternative Pathway ◽  
Nitrogen Sources ◽  
Maximum Production ◽  
Aspergillus Flavus Group

A number of molds and bacteria were screened for their ability to degrade quercitrin. The molds, but not the bacteria, were particularly active and produced carbon monoxide. The degradation of quercitrin is dependent upon the synthesis of an inducible glycosidase (quercitrinase). This enzyme is synthesized by only a few members of the Aspergillus flavus group. Two of these strains synthesized quercitrinase and excreted it and other enzymes into the culture medium. Maximum production of quercitrinase was obtained with organic nitrogen sources such as yeast extract or phytone. Quercitrinase is induced by readily metabolized flavonols and flavonol-glycosides. The glycosidase is quite specific, liberating the rhamnose from the 3-position of quercitrin and myricitrin and the 7-position of robinin. The aglycone, quercetin, is subsequently metabolized to carbon monoxide and the depside of phloroglucinol-carboxylic acid and proto-catechuic acid. Evidence is also presented for an alternative pathway for the metabolism of the flavonol nucleus.

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