PA-1, a Versatile Anaerobe Obtained in Pure Culture, Catabolizes Benzenoids and Other Compounds in Syntrophy with Hydrogenotrophs, and P-2 plus Wolinella sp. Degrades Benzenoids

Abstract

Methanogenic enrichments catabolizing 13 mM phenylacetate or 4 mM phenol were established at 37°C, using a 10% inoculum from a municipal anaerobic digester. By using agar roll tubes of the basal medium plus 0.1% yeast extract-25 mM fumarate, a hydrogenotrophic lawn of Wolinella succinogenes and phenol or phenylacetate, strains P-2 and PA-1, respectively, were isolated in coculture with W. succinogenes. With the lawn deleted, PA-1 was isolated in pure culture. Strain P-2 is apparently a new species of anaerobic, motile, gram-negative, spindle-shaped, small rod that as yet has been grown only in coculture with W. succinogenes. It used phenol, hydrocinnamate, benzoate, and phenylacetate as energy sources. Product recovery by the coculture, per mole of phenol and 4.4 mol of fumarate used, included 2.03, 0.12, 0.08, and 3.23 mol, respectively, of acetate, propionate, butyrate, and succinate. Carbon recovery was 75% and H recovery was 80%, although CO2 and a few other possible products were not determined. That P-2 is an obligate proton-reducing acetogen and possible pathways for its degradation of phenol are discussed. Strain PA-1 is apparently a new species of anaerobic, motile, relatively small, gram-negative rod. It utilized compounds such as phenylacetate, hydrocinnamate, benzoate, phenol, resorcinol, gallate, 4-aminophenol, 2-aminobenzoate, pyruvate, Casamino Acids, and aspartate as energy sources in coculture with W. succinogenes. Per mole of phenylacetate and 1.44 mol of fumarate used, 1.04, 0.53, and 0.78 mol of acetate, propionate, and succinate, respectively, were recovered from the coculture. Only about 50% of the carbon and H were recovered. In coculture with Methanospirillum hungatei, 0.96 mol of acetate and 0.25 mol of methane were recovered per mol of pyruvate used; 0.90 mol of acetate and 0.33 mol of methane, per mol of fumarate used; 0.93 mol of acetate and 0.54 mol of methane, per mol of aspartate used; and 1.71 mol of acetate and 0.57 mol of methane, per mol of glucose used. Carbon and H recoveries, assuming CO2 and ammonia were produced in stoichiometric amounts, were 97 and 98% for pyruvate, 72.5 and 82% for fumarate, 96.5 and 98% for aspartate, and 61.8 and 76% for glucose. No explanation such as contamination could be found for the fact that the coculture PA-1 plus Wolinella sp. did not use glucose; after growth with M. hungatei on pyruvate, however, the latter coculture used glucose. The PA-1 pure culture produced 0.86 mol of propionate per mol of succinate used during growth. PA-1 produced a small amount of H2. Strain PA-1 is the most versatile anaerobic bacterium yet known that catabolizes monobenzenoids in the absence of electron acceptors such as sulfate or nitrate.

Molecular characterization of a sulfate-reducing consortium which mineralizes benzene

“…Co-cultures of anaerobes similar to Syntrophus sp. and Wolinella succinogenes have been shown to degrade several aromatic compounds including phenol and benzoate [34]. The remaining six clones are either distantly related to known genera or are related to poorly described organisms (SB-22) and hence little insight can be gained about their role.…”

A mathematical model of syntrophic cocultures in the chemostat (Anaerobic degradation; H2-producing acetogenic bacteria; methanogens; interspecies H2-transfer; continuous culture; growth rate expressions)

“…The steady state system of (1) reads -g,(Cs,, Cs2)~ --L + D(C R -Csl ) =0, Table 1 The solutions of the batch case at various initial conditions Table 2 The three solutions of the chemostat case For definition of the functions ~j(D) (j=l, 2, 3), ~p(D) see text (Eqns. (12), (13), (14a), (14b)).…”

“…The functions (12), (13) and (14b) give the substrate concentration of the first organism in the three steady states. Note that (14a) describes the steady-state substrate concentration of the second organism.…”

“…The first components are the functions ¢p,, %, % given by Eqns. (12), (13) and (14b), respectively. These are plotted in Fig.…”

“…At the first stage, hydrolytic and acidogenic bacteria hydrolyze polymers and ferment the monomers to organic acids, alcohols, CO 2 and H 2. The second group consists of H2-producing acetogenic bacteria that convert alcohols [2][3][4], fatty acids [5][6][7][8][9], amino acids [10], and aromatic compounds [11][12][13][14] almost exclusively to acetate, H 2 and CO 2. At the third stage, methane is formed by methanogenic bacteria utilizing as main substrates the acetate and the H 2 (plus CO2) produced by the other groups [15].…”