Optimization of GelGreen^™ concentration in CsCl density gradients.

<p>The concentrations of GelGreen^™ (from left to right) were 1X, 5X, 10X, 15X, 20X, 25X, 30X and 50X in CsCl density gradients, respectively. The locations of DNA bands are pointed by arrows.</p

Quantitative distribution of bacterial 16S rRNA gene copy number across all the fractions.

<p>Quantitative distribution of bacterial 16S rRNA gene copy number across all the fractions.</p

Molecular structures of GelGreen^™ (a) and SYBR^® Safe (b).

<p>Molecular structures of GelGreen^™ (a) and SYBR^® Safe (b).</p

Visualization of DNA bands stained by GelGreen^™ with environmental DNA after SIP incubation (a) and relative abundance of bacterial 16S rRNA gene, <i>amoA</i> gene of AOA and AOB (b).

<p>In Fig 7a, 5 μg and 10 μg labeled-DNA were added into samples A and B, respectively. Fractions I, II, III, IV and V show the range of fractions fractionated by needles and syringes.</p

Detection limit of environmental DNA in CsCl density gradients stained by GelGreen^™ under its optimal concentration.

<p>From left to right, 0 μg, 0.1 μg, 0.2 μg, 0.5 μg, 0.8 μg, 1.0 μg, 2.0 μg and 5.0 μg environmental DNA were used. The locations of DNA bands are indicated by arrows. Fractions I, II, III and IV show the range of fractions withdrawn by needles and syringes.</p

Schematic diagram summarizing steps of modified needle extraction.

<p>Fractions I, II, III, IV and V show the range of fractions withdrawn by needles and syringes.</p

Comparison of GelGreen^™ and SYBR^® Safe staining with 5 μg environmental DNA in CsCl density gradients with TE or GB buffer.

<p>A, B, C and D treatment represent GelGreen^™ in TE buffer, GelGreen^™ in GB buffer, SYBR^® Safe in TE buffer and SYBR^® Safe in GB buffer, respectively. The locations of DNA bands are pointed by arrows.</p

Metatranscriptome Revealed the Efficacy and Safety of a Prospective Approach for Agricultural Wastewater Reuse: Achieving Ammonia Retention during Biological Treatment by a Novel Natural Inhibitor Epsilon-Poly‑l‑Lysine

Appropriate inhibitors might play important roles in achieving ammonia retention in biological wastewater treatment and its reuse in agriculture. In this study, the feasibility of epsilon-poly-l-lysine (ε-PL) as a novel natural ammonia oxidation inhibitor was investigated. Significant inhibition (ammonia oxidation inhibition rate was up to 96.83%) was achieved by treating the sludge with ε-PL (400 mg/L, 12 h soaking) only once and maintaining for six cycles. Meanwhile, the organic matter and nitrite removal was not affected. This method was effective under the common environmental conditions of biological wastewater treatment. Metatranscriptome uncovered the possible action mechanisms of ε-PL. The ammonia oxidation inhibition was due to the co-decrease of Nitrosomonas abundance, ammonia oxidation genes, and the cellular responses of Nitrosomonas. Thauera and Dechloromonas could adapt to ε-PL by stimulating stress responses, which maintained the organic matter and nitrite removal. Importantly, ε-PL did not cause the enhancement of antibiotic resistance genes and virulent factors. Therefore, ε-PL showed a great potential of ammonia retention, which could be applied in the biological treatment of wastewater for agricultural reuse