Table 1 PLSR model summaries of 13C-enriched VOCs (acetate, acetone and diacetyl+) fluxes after labelling with 13C2-pyruvate

From: Drought re-routes soil microbial carbon metabolism towards emission of volatile metabolites in an artificial tropical rainforest

VOC model

Gene

KO

Produce (p) or consume (c)

Variable (enzyme/VOC efflux/physiochemical)

VIP

PLSR weight

w1

w2

Acetate

na

na

na

acetone-C2 efflux

1.51

0.61

0.28

ACH1

K01067

p

acetyl-CoA hydrolase

1.21

0.48

0.15

aarC

K18118

c

succinyl-CoA:acetate CoA-transferase

1.05

0.21

−0.23

na

na

na

soil moisture (%)

1.02

−0.42

–

poxL

K00158

p

pyruvate oxidase

0.92

0.17

−0.53

poxB

K00156

p

PDH-quinone

0.90

0.18

−0.50

acyP

K01512

p

acylphosphatase

0.86

–

0.28

acs

K01895

c

acetyl-CoA synthase

0.82

−0.21

0.12

pct

K01026

p

propionate CoA-transferase

0.82

−0.28

–

ackA

K00925

c

acetate kinase

0.75

–

0.46

    

R2- total 0.91 (6 comp.)

 

0.51

0.20

Acetone

na

na

na

acetate-C2 efflux

1.36

0.61

–

adc

K01574

p

acetoacetate decarboxylase

1.05

0.47

–

na

na

na

soil moisture (%)

1.00

−0.44

–

adh1

K18382

c

NAD+-dependent secondary alcohol dehydrogenase

0.80

0.36

–

acmA

K18371

c

acetone monooxygenase

0.64

−0.29

–

    

R2- total 0.76 (1 comp.)

 

0.76

–

Diacetyl+

na

na

na

soil moisture (%)

1.12

–

0.99

butA

K03366

c

meso-butanediol dehydrogenase

0.86

–0.99

–

   

R2- total 0.23 (2 comp.)

 

0.15

0.08

  1. PLSR models were created with single response variables (fluxes for each of the 13C-enriched VOCs) and predictor variables that included expression of genes known to produce or consume each 13C-enriched VOC and soil moisture (%). The VIP values represent the degree of importance of each predictor variable on the response variable. The PLSR weights (w) depict the magnitude and direction of contribution of each predictor variable (+ or − relationship) on the response variable along the first and/or second component (w1 and w2), with a dash indicating a lack of contribution to that component. Genes or physicochemical properties that were determined to not contribute to each model are not shown (see Methods). 13C-enriched VOC fluxes and gene expression data are from three collars that received 13C2-pyruvate at 0, 6 and 48 h post pyruvate injection during pre-drought and drought conditions (n = 18). The total percentage of variance explained (R2) from predictor variables for all components (comp., shown in parentheses) in the optimized model is shown in the bottom row for each VOC model in bold. The R2 broken down by the first and second components are shown below w1 and w2, respectively, in bold. Acetone-C2 efflux was included in the model for acetate-C2, and acetate-C2 efflux was included in the model for acetone-C2 due to the high correlation between acetate-C2 and acetone-C2.
  2. na, not applicable; +, C4H6O2 represents diacetyl and/or one other unidentifiable compound.
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