deletions | additions       diff --git a/Results.tex b/Results.tex  index b9d6bd0..5a75c15 100644  --- a/Results.tex  +++ b/Results.tex 
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$^{13}$C-xylose assimilating organisms utilized $^{13}$C-xylose as a sole  carbon source.  \subsection{Cellulose degrader DNAexhibits greater bouyant density  shifts further along the BD gradient  upon $^{13}$C incorporation than xylose degrader DNA}   Cellulose responders exhibited a greater shift in BD(i.e. assimilated more  $^{13}$C per unit DNA)  than xylose responders in response to isotope incorporation (Figure~\ref{fig:shift}, p-value 1.86e$^{-06}$). Cellulose $^{13}$C-cellulose  responders exhibited an shifted on  averageshift of  0.0163 g/mL (sd 0.0094) whereas xylose responders exhibited an shifted on  averageshift of  0.0097 (sd 0.0094). One hundred percent For reference, 100\%  $^{13}$C DNA has a buoyant density shifts  X.XX g/mL higher than relative to the BD of  its $^{12}$C counterpart. DNA buoyant density BD  increases as the its  ratio of $^{13}$Ccarbons  to $^{12}$C increases. An organism that only assimilates C into DNA from a $^{13}$C isotopically labeled source, will have a  greater $^{13}$C:$^{12}$C ratio in its DNA than an organism utilizing a mixture  of isotopically labeled and unlabeled C sources. Upon labeling, DNA from the an  organism that incoporates incorporates  exclusively $^{13}$C will shift its increase in  buoyant density position further relative to its original $^{12}$C-DNA position more  thanthe  DNAbuoyant density shift  from an organism that doesn't does not  exclusively utilize isotopically labeled C. Therefore the magnitude  DNA buoyant density shifts(labeled versus  unlabeled DNA)  indicate substrate specificity given our experimental design (only as only  one substrate was labeled in each amendment). amendment.  We measured density shift as the change in an OTU's density profile center of mass between corresponding contol and labeled gradients. Density shifts, however, should not be evaluated  on an individual OTU basis as a small number of density shifts are observed for  each OTU and the variance of the density shift metric at the level of 
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utilizers for xylose (Figure~\ref{fig:shift}), and, each responder group  exhibits a range of substrate specificites (Figure~\ref{fig:shift}).  \subsection{Xylose responders at day 1 have more estimated rRNA operon copy numbers per genome than xylose responders at days 3 and 7, and, Xylose responders have more rRNA operon copy numbers than cellulose responders.}  Estimated rRNA operon genome copy numbers per $^{13}$C-xylose responder OTU  genome and day of first response are correlated (p-value 2.02e$^{-15}$,  Figure~\ref{fig:copy}). $^{13}$C-xylose responder rRNA operon geneome genome  copy number is inversely related to time; that is, time of first response (p-value 2.02e$^{-15}$, Figure~\ref{fig:copy}).  OTUs that first respond at later time points have fewer estimated rRNA operons per genome than OTUs that first respond earlier (Figure~\ref{fig:copy}). rRNA operon copy number estimation is a recent advance in microbiome science \citep{Kembel_2012} and while  the relationship of rRNA operon copy number per genome with ecological strategy is well established \citep{Klappenbach_2000}. Specifically, microorganisms Microorganisms  with a high number of rRNA operons per genome tend to be fast growers specialized to take advantage of boom-bust environments whereas a microorganisms with  low rRNA operon copy number numbers  per genometends to occur in microorganisms that  favor slower growth under lower and more consistent nutrient input \citep{Klappenbach_2000}. At the beginning of our incubation, OTUs with estimated high rRNA operon copy numbers per genome or ``fast-growers'' assimilate xylose into biomass and with time slower growers (lower rRNA operon number per genome) begin to respond to the xylose addition. Further, $^{13}$C-xylose responders have more estimated rRNA operon copy numbers per genome than $^{13}$C-cellulose responders (p-value 1.878e$^{-09}$) suggesting xylose respiring mircrobes microbes  are generally faster growers than cellulose degraders. \subsection{Xylose responders are more abundant in the soil community than cellulose  responders}  $^{13}$C-xylose responders are generally more abundant members based on  relative abundance in bulk DNA SSU rRNA gene content than $^{13}$C-cellulose  responders (Figure~\ref{fig:shift}, p-value 0.00028). However, both$^{13}$C-xylose  and $^{13}$C-cellulose responders were found in  abundant and rare OTUs responded to $^{13}$C-xylose and $^{13}$C-cellulose  (Figure~\ref{fig:shift}). For instance, a \textit{Delftia} $^{13}$C-cellulose  responder is fairly abundant in the bulk samples (``OTU.5'',  Table~\ref{tab:cell}) with a mean bulk rank of 13 (\textit{i.e.} Table~\ref{tab:cell}). OTU.5 was  on average the 13th most abundant OTU) and a OTU in bulk samples. A  $^{13}$C-xylose responder (``OTU.1040'', Table~\ref{tab:xyl}) has a mean relative abundance in bulk samples of 2.85e$^{-05}$. Only one substrate responder ($^{13}$C-cellulose) was not found in any bulk samples ("OTU.862", Table~\ref{tab:cell}). Of thetop 10  responders sorted by descending mean rank (essentially the  10 most abundant respondersin the bulk samples),  8 are $^{13}$C-xylose responders and 5 of these 8 have mean ranks less than are consistently  among the  10 most abundant OTUs  in bulk samples. \subsection{Variation in bulk soil DNA microbial community structure is significantly less than variation in gradient fractions} Using a distance metric that incorporates relative abundance information  (weighted Unifrac metric, \citep{Lozupone_2005}) bulk sample beta diversity was  less than gradient fraction beta diversity (p.value (p-value  0.003). Time was significantly correlated to bulk sample phylogenetic profile variation (p-value  0.23, R$^{2}$ 0.63, Figure~\ref{fig:bulk_ord}) buttreatment (\textit{i.e.}  the contrast between only $^{12}$C additions with additions that included isoptically isotopically  labeled substrates) substrates  was not (p-value 0.35).