Performance and Yield

Performance and Yield

<b>8. Performance and Yield Data</b> Methanotrophs have been considered for use in industrial applications since the 1970s, and a variety of studies have assessed performance and yield data for these bacteria, including both gamma- and alpha-proteobacteria.  Table 8.1 shows values reported for either theoretical predictions (<a title="Anthony, 1978 #10" href="/wiki/references#_ENREF_14">Anthony, 1978</a>, <a title="Anthony, 1982 #8" href="/wiki/references#_ENREF_15">1982</a>; <a title="Leak, 1986 #142" href="/wiki/references#_ENREF_117">Leak and Dalton, 1986b</a>)(Anthony, 1978, 1982; Leak &amp; Dalton, 1986b) or experimental measurements (<a title="Harwood, 1972 #106" href="/wiki/references#_ENREF_88">Harwood and Pirt, 1972</a>; <a title="Lamb, 1980 #138" href="/wiki/references#_ENREF_115">Lamb and Garver, 1980</a>; <a title="Leak, 1986 #141" href="/wiki/references#_ENREF_116">Leak and Dalton, 1986a</a>; <a title="Park, 1991 #189" href="/wiki/references#_ENREF_140">Park et al., 1991</a>; <a title="Park, 1992 #192" href="/wiki/references#_ENREF_141">Park et al., 1992</a>). The values that have been obtained vary depending on which assimilation pathway was utilized, which form of the MMO was expressed, and which nitrogen source was used.  Growth rates vary widely, depending on the strain. &nbsp; <table width="637" border="1" cellspacing="0" cellpadding="0"> <tbody> <tr> <td valign="top" width="67"><b> </b></td> <td valign="top" width="62"><b> </b></td> <td colspan="4" valign="top" width="220"><b>Theoretical Predictions</b></td> <td colspan="5" valign="top" width="288"><b>Experimental Measurements</b></td> </tr> <tr> <td valign="top" width="67"><b>Strain Type</b></td> <td valign="top" width="62"><b>MMO</b></td> <td valign="top" width="50"><b>Y</b></td> <td valign="top" width="44"><b>% CO₂</b></td> <td valign="top" width="60"><b>CCE</b></td> <td valign="top" width="66"><b>% energy</b></td> <td valign="top" width="42"><b>Y</b></td> <td valign="top" width="60"><b>% CO₂</b></td> <td valign="top" width="42"><b>CCE</b></td> <td valign="top" width="72"><b>Biomass</b></td> <td valign="top" width="72"><b>μ</b><b>^-1</b><b></b></td> </tr> <tr> <td valign="top" width="67">Gamma</td> <td valign="top" width="62">pMMO</td> <td valign="top" width="50">1.09</td> <td valign="top" width="44">31</td> <td valign="top" width="60">38-63</td> <td valign="top" width="66">35-63</td> <td valign="top" width="42">1.2</td> <td valign="top" width="60">33.5</td> <td valign="top" width="42">43.3</td> <td valign="top" width="72">20-25</td> <td valign="top" width="72">0.2-0.37</td> </tr> <tr> <td valign="top" width="67">Gamma</td> <td valign="top" width="62">sMMO</td> <td valign="top" width="50">0.75</td> <td valign="top" width="44">54</td> <td valign="top" width="60">32-42</td> <td valign="top" width="66">54-66</td> <td valign="top" width="42">0.8</td> <td valign="top" width="60">64</td> <td valign="top" width="42">31</td> <td valign="top" width="72">25-29</td> <td valign="top" width="72">0.02-0.2</td> </tr> <tr> <td valign="top" width="67">Alpha</td> <td valign="top" width="62">pMMO</td> <td valign="top" width="50">0.94</td> <td valign="top" width="44">42</td> <td valign="top" width="60">34-54</td> <td valign="top" width="66">34-80</td> <td valign="top" width="42">0.8</td> <td valign="top" width="60">-</td> <td valign="top" width="42">-</td> <td valign="top" width="72">6-20</td> <td valign="top" width="72">0.12</td> </tr> <tr> <td valign="top" width="67">Alpha</td> <td valign="top" width="62">sMMO</td> <td valign="top" width="50">0.65</td> <td valign="top" width="44">60</td> <td valign="top" width="60">36-39</td> <td valign="top" width="66">57-68</td> <td valign="top" width="42">0.22-0.5</td> <td valign="top" width="60">88</td> <td valign="top" width="42">-</td> <td valign="top" width="72">3</td> <td valign="top" width="72">0.013-0.08</td> </tr> </tbody> </table> Y, g cell dry wt/g substrate; % CO₂, % methane oxidized to CO₂; CCE, carbon conversion efficiency (% CH₄ metabolized for biomass); % energy, % methane metabolized for energy; biomass, g wet wt/L fermentation broth; μ^-1, specific growth rate. &nbsp; Although it may be predicted that the yields of methanotrophs should be higher using ammonium as a nitrogen source instead of nitrate, in fact, the reported yields are similar (<a title="Leak, 1986 #141" href="/wiki/references#_ENREF_116">Leak and Dalton, 1986a</a>).