Methane- and ammonia-oxidizing bacteria at the chemocline of Lake Kinneret (Israel)

Abstract

The vertical distribution of methane- and ammonia-oxidizing bacteria (MOB and AOB, respectively), and the physicochemical conditions in the chemocline of Lake Kinneret (Israel) were studied at a resolution of 10 cm from 16.2 to 17.7 m depth. Profiles of the chemical parameters indicated decreasing concentrations of methane (from 22.4 to 0.11 µmol l–1) and ammonia (from 14.2 to 8.4 µmol l–1) towards the water surface and in close proximity to the chemocline. The disappearance of methane coincided with methane oxidation that could be corroborated throughout this layer with highest rates at 17.4 to 17.6 m. Disappearance of ammonia could not be linked to ammonia oxidation exclusively. The genes pmoA and the homologous amoA (coding for subunit α of the methane and ammonia monooxygenase, respectively) were amplified by PCR. The products were analyzed by terminal restriction fragment length polymorphism (T-RFLP) and sequencing of clone libraries. The results demonstrated that different MOB and AOB communities are established along the concentration gradient within the narrow layer of the metalimnetic chemocline. Changes in the intensity of the T-RFLP peaks and the frequency of different groups of alpha- and gammaproteobacterial MOB, and betaproteobacterial AOB, coincided with the concentration gradients of methane, ammonia, nitrate, and oxygen in the chemocline. This suggests that different communities of MOB, and to a lesser extent AOB, contribute to the formation of chemical gradients of their particular substrates in the chemocline

Methanotrophy under Versatile Conditions in the Water Column of the Ferruginous Meromictic Lake La Cruz (Spain)

“…The first three were most closely related to uncultured species from other freshwater lakes, reservoirs, and sediments: Lake Mizugaki (Kojima et al, 2009; Tsutsumi et al, 2011), Feitsui Reservoir (Kojima et al, 2014), Lake Cadagno (Milucka et al, 2015), Lake Kinneret (Junier et al, 2010), Lake Schoehsee (unpublished), Lake Constance (Pester et al, 2004), and lakes on the Yunnan Plateau (Liu et al, 2015). The fourth cluster was closely related to an uncultured Methylococcus species from a wetland in northeast China (Yun et al, 2013) and an uncultured bacterium from lake sediments (Liu et al, 2015).…”

Global co‐occurrence of methanogenic archaea and methanotrophic bacteria in Microcystis aggregates

“…The higher dissolved organic carbon (DOC) concentrations observed in Lake Clarendon and Wentowsee (Supporting Information Table S3) may have increased the activity and abundance of MOB by relieving light inhibition in surface waters (Thottathil et al ., 2018) or by providing carbon for anaerobic bacteria living within the aggregates to produce methane. Previous results from a high MOB lake (Lac de Villerest) along with two low MOB lakes (Grand Lake and Lake Kinneret), showed MOB present in their mid‐water column where diffusive CH 4 /O 2 counter‐gradients meet during the stratification period (Junier et al ., 2010; Morrison et al ., 2017; Pradeep Ram et al ., 2019). Considering that Lac de Villerest was sampled during the early period of turnover (October), while the other two lakes were sampled at the beginning of the stratification period (Supporting Information Table S3), we speculate that abundant MOB may have been circulated to the surface during the fall turnover in Lac de Villerest and subsequently recruited into bloom aggregates.…”