Comparative proteomic analysis reveals insights into anoxic growth of Methyloversatilis universalis FAM5 on methanol and ethanol

Abstract

Methyloversatilis universalis FAM5 is a facultative methylotrophic bacterium that has been found in a variety of natural and engineered ecosystems. The goal of this study was to investigate M. universalis FAM5 responses to different electron/carbon donors, e.g. methanol or ethanol, during anoxic growth in chemostats with nitrate as the electron acceptor. During steady-state anoxic growth on either methanol or ethanol, over 90% of the influent nitrate was reduced primarily to nitrite. The cell yield on methanol was lower, possibly due to high energy requirements for C(1) assimilation. Label-free proteomics further revealed that methanol-grown cells displayed elevated concentrations of the enzymes involved in C(1) metabolism (H(4)MPT/H(4) F pathways, formate oxidation and serine cycle). In contrast, C(2) metabolism (glyoxylate shunt and tri-carboxylic acid cycle) and polyhydroxy-β-butyrate (PHB) synthesis related proteins were overrepresented during subsequent growth on ethanol. Notably, the expression of respiratory nitrate reductase was not affected by the carbon sources applied. Furthermore, the changes in the proteome upon switching back to methanol were mostly reversible. Therefore, M. universalis displays wide-ranging responses to adapt between growth on methanol and ethanol. Such metabolic versatility could be particularly useful in wastewater treatment systems, which need to switch between different electron donors, while still reliably meeting effluent nitrogen discharge goals.

Sulfur-based mixotrophic denitrification corresponding to different electron donors and microbial profiling in anoxic fluidized-bed membrane bioreactors

“…These suggest that the addition of methanol or ethanol had a clear effect on the microbial community structure. For a given system, the carbon source has a remarkable potential impact on the denitrifying community structure than others, as organic carbon determines various metabolic pathways of heterotrophic bacteria (Baytshtok et al, 2009;Lu et al, 2014;Hallin et al, 2006;Wan et al, 2011;Lu et al, 2012).…”

Differentiation in the microbial ecology and activity of suspended and attached bacteria in a nitritation‐anammox process

“…Such seemingly stochastic changes in microbial ecology over long term, some of which don't always correlate with process changes have been previously observed (Ahn et al, 2008;Park et al, 2010a,b). On the other hand, changes in microbial structure and function have also been observed, which indeed correlate with process level changes, such as changes in the type of organic carbon for denitrification (Baytshtok et al, 2009;Lu et al, 2012;Lu and Chandran 2010) or changes in the operating mode (partial or full nitrification) (Ahn et al, 2011).…”

Prerequisites for amplicon pyrosequencing of microbial methanol utilizers in the environment

“…In addition, many more methylotrophs that have the ability to use nitrate as an alternative electron acceptor have not yet been tested for anaerobic methanol oxidation (Bamforth and Quayle, 1978; Kolb, 2009a); recent examples, in which the physiology has been thoroughly assessed, are Methyloversatilis universalis FAM5, and Methylotenera versatilis (Kalyuzhnaya et al, 2012; Lu et al, 2012; Mustakhimov et al, 2013). In environments with a high nitrogen input (for example by fertilization) and turnover, facultative aerobic and nitrate-dependent degradation of methanol likely occurs in oxygen-limited zones (Lu et al, 2012). Based on the current knowledge, these organisms are accessible by the same gene markers as described in the following section ( Figure 1 ).…”