Effects of Organic Phosphorus on Methylotrophic Methanogenesis in Coastal Lagoon Sediments With Seagrass (Zostera marina) Colonization

Abstract

Methanogens are the major contributors of greenhouse gas methane and play significant roles in the degradation and transformation of organic matter. These organisms are particularly abundant in Swan Lake, which is a shallow lagoon located in Rongcheng Bay, Yellow Sea, northern China, where eutrophication from overfertilization commonly results in anoxic environments. High organic phosphorus content is a key component of the total phosphorus in Swan Lake and is possibly a key factor affecting the eutrophication and carbon and nitrogen cycling in Swan Lake. The effects of organic phosphorus on eutrophication have been well-studied with respect to bacteria, such as cyanobacteria, unlike the effects of organic phosphorus on methanogenesis. In this study, different sediment layer samples of seagrass-vegetated and unvegetated areas in Swan Lake were investigated to understand the effects of organic phosphorus on methylotrophic methanogenesis. The results showed that phytate phosphorus significantly promoted methane production in the deepest sediment layer of vegetated regions but suppressed it in unvegetated regions. Amplicon sequencing revealed that methylotrophic Methanococcoides actively dominated in all enrichment samples from both regions with additions of trimethylamine or phytate phosphorus, whereas methylotrophic Methanolobus and Methanosarcina predominated in the enrichments obtained from vegetated and unvegetated sediments, respectively. These results prompted further study of the effects of phytate phosphorus on two methanogen isolates, Methanolobus psychrophilus , a type strain, Methanosarcina mazei , an isolate from Swan Lake sediments. Cultivation experiments showed that phytate phosphorus could inhibit methane production by M. psychrophilus but promote methane production by M. mazei . These culture-based studies revealed the effects of organic phosphorus on methylotrophic methanogenesis in coastal lagoon sediments and improves our understanding of the mechanisms of organic carbon cycling leading to methanogenesis mediated by organic phosphorus dynamics in coastal wetlands.

Diverse methylotrophic methanogenic archaea cause high methane emissions from seagrass meadows

“…However, Methanococcoides have also been reported to be capable of using choline and glycinebetaine directly ( 55 , 56 ) and do not necessarily require a bacterial partner for methane production. In a recent study, Methanococcoides , Methanosarcina , and Methanolobus species were successfully enriched on methylated compounds from Zostera seagrass sediments ( 57 ). Based on our combined results, we thus propose that members of these cosmopolitan and ubiquitous methylotrophic methanogens were likely responsible for methane production in P. oceanica seagrass meadows.…”

Seasonal Dynamics of Bathyarchaeota-Dominated Benthic Archaeal Communities Associated with Seagrass (Zostera japonica) Meadows

“…Recently, a spatial comparison of the archaeal community among seagrass meadows was reported [17,18]. Seagrass vegetation selectively enriched Woesearchaeota (Woese-3 and Woese-21), Bathyarchaeota (Bathy-6 and Bathy-18), as well as methanogenic archaea [18,19], revealing that there is ecological niche separation of archaeal taxa between seagrass-vegetated and adjacent unvegetated sediments [18]. Beyond seagrass ecosystems, the spatial patterns in archaeal distribution have been described for several coastal marine environments, including the Antarctic coastal waters [20], mangrove and intertidal wetland mudflats [21,22], the coast of the North Sea [23], and Shark Bay mats [24].…”

Dynamics of Methane in Mangrove Forest: Will It Worsen with Decreasing Mangrove Forests?

“…Apart from sulphate supply, fresh organic matter supply was often found to be strongly correlated with methane-procuring activities [39]. Consistently, several reports have described that surface layer sediment has greater methaneproducing activity and contains higher soil organic matter content compared to other sediment [101,103]. However, the substrate supply in sediment is spatio-temporally heterogenous because it is affected by tidal pumping, crab/goby burrowing, and the structural complexity of aerial mangrove tree roots [60].…”