Nitrate decreases methane production also by increasing methane oxidation through stimulating NC10 population in ruminal culture

Abstract

Studies proved that addition of nitrate in rumen could lead to reduction of methane emission. The mechanism of this function was involved in the competition effect of nitrate on hydrogen consumption and the inhibitory effect of generated nitrite on methanogen proliferation. The present study investigated an alternative mechanism that denitrifying anaerobic methane oxidizing (DAMO) bacteria, DAMO archaea and anammox bacteria may co-exist in rumen, therefore, more methane can be oxidized when addition of nitrate. Ruminal batch culture model was used to test the effects of addition of 5 mM NaNO3, 4 mM NH4Cl, or both into the culture substrate on methane production, fermentation patterns, and population of methanogens, NC10 and anaerobic methanotrophic-2d (ANME-2d). Our results showed that NC10 in the ruminal culture was detected by polymerase chain reaction (PCR) when using NC10 special primer sets, and addition of nitrate reduced methane production and the relative proportions of methanogen, whereas increased the relative proportion of NC10. A combined addition of ammonia salt and nitrate did not show further inhibitory effect on methane production but accelerated nitrate removal. We did not detect DAMO archaea in ruminal culture by real-time PCR when using ANME-2d special primer sets. The present study may encourage researchers to pay more attention to methane oxidation performed by anaerobic methanotroph when studying the strategies of inhibiting ruminal methane emission.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-017-0377-2) contains supplementary material, which is available to authorized users.

Rumen microbial responses to supplemental nitrate. II. Potential interactions with live yeast culture on the prokaryotic community and methanogenesis in continuous culture

“…The percentage of protozoal N derived from bacterial N is low in the current study, probably because of feed N contamination of protozoal samples; thus, protozoal 15 N enrichment was diluted and could not be fixed (data not shown) by the boiling approach described by Ye et al (2018). Although the potential for denitrification of nitrates to N 2 or N 2 O has also been speculated to become a more prevalent route of NO 2 − reduction while CH 4 emission is suppressed (Liu et al, 2017), Latham et al (2016) summarized denitrification to be minor in the rumen but suggested that such alternative routes deserve future research. The lack (P > 0.15) of treatment effect on bacterial N flow or bacterial N derived from NH 3 -N does not support decreased NH 3 -N assimilation.…”

Rumen-protected methionine a feed supplement to low dietary protein: effects on microbial population, gases production and fermentation characteristics

“…The copy number of each standard plasmid was calculated using as described by Yu et al (2005), and the DNA standard calibration curve was made. The 16S rDNA copy numbers of cellulolytic species and total bacteria were calculated as by Zhao et al (2013), and Liu et al (2017). The real-time PCR was performed on ninety-six-well optical plates using CFX96TM Bio-Rad-IQ5 PCR System (Bio-Rad, Lab, Inc, Hercules, USA), was used for PCR assays with SYBR Green Dye Premix Ex Taq™II (Takara, Dalian, Liaoning, China).…”

Simultaneous Supplementation of Bacillus subtilis and Antibiotic Growth Promoters by Stages Improved Intestinal Function of Pullets by Altering Gut Microbiota

“…The bacteria specific primer sets were shown in Table 2 . The qPCR plasmid standard was prepared according to the method described in a previous study (Liu et al, 2017a ). After that, the concentration of plasmid standards of C .…”