Search

Seven pradimicin-like polyketides were isolated from the dichloromethane extract of the marine sediment-derived Streptosporangium sp. CGMCC 4.7309, including five new hexaricins, D–H (1–5), and known hexaricins A (6) and C (7). Their structures were determined by HRESIMS, 1D and 2D NMR, and other spectroscopic analyses. The absolute configurations of compounds 1–5 were determined on the basis of circular dichroism and specific rotation data. All isolated compounds 1–7 were tested for their antioxidant capacities by DPPH• scavenging, •OH scavenging, and •O2 scavenging assays. Compounds 3 and 4 displayed stronger antioxidant activities than the positive control (tert-butylhydroquinone). The relationship between structure and antioxidant activity is discussed. These compounds could be effective natural antioxidants with considerable pharmaceutical value.

To provide new atrazine-degrading strains for atrazine-polluted soil, we isolated the high-efficiency degradation bacterium from contaminated soil, identified with taxonomy, and studied the degrading characteristics and remediation capability of the strain in black soil.We used morphological, physiological and biochemical characteristics and 16S rDNA sequences analysis to identify the strain. We studied the effect of environmental factors such as incubation time, temperature and pH on the strain growth and atrazine degradation to confirm the optimum degradation conditions. The strain's degradation range was studied by using different herbicides as sole carbon and nitrogen source. The strain's remediation capability to atrazine-polluted soil was tested by sensitive crop bioassay after inoculating in pot soil.We isolated a high-efficiency degradation strain T3AB1 that used atrazine as sole carbon and nitrogen source from maize field suffering atrazine in Nehe, Heilongjiang province. It was initially identified as a member of the genus Arthrobacter sp.. The strain could degrade more than 99% of 500 mg/L atrazine (pH 8.0) within 72 h. We determined the best degradation conditions as follows: pH 7.0-8.0, 25-30 degrees C, 72-108 h. In addition, the strain used other herbicides as sole carbon and nitrogen source such as imazamox, imazethapyr, trifluralinm, clomazone and fomesafen, and the degradation rate reached 12.66% - 40.54% after 168 h. The strain could significantly remedy the sensitive rice crop biomass indexes after treating 21 days, and as time extending, its role in the remediation gradually increased.The screened atrazine-degrading strain T3AB1 could be a suitable candidate for bioremediation of atrazine-polluted soil.