80 DECOMPOSITION OF ORGANIC SUBSTANCES IN SOIL 



glucuronic, citric, oxalic, fumaric, and succinic acids, as shown in 

 the following reactions: 



CsHisOe + O2 = CHO • (CH0H)4 • COOH + H2O 



Glucose Glucuronic 



acid 



CeHioOe + UO2 



Glucose 



= CH2 • COOH • COH • COOH -CHs- COOH + 2H2O 



Citric acid 



C6H12OC + 4IO2 = 3(COOH)2 + 3H2O 



Glucose Oxalic acid 



C6H12OC + 6O2 = 6CO2 + 6H2O 



Glucose 



Bacteria decompose sugars in a manner quite different from 

 that of the fungi, and the resulting end products are determined 

 principally by the presence or absence of free oxygen. Lactic, 

 butyric, acetic, propionic, formic, and valerianic acids, methane 

 and hydrogen are some of the products formed under anaerobic 

 conditions; frequently butyl alcohol, ethyl alcohol, and acetone 

 are also produced under these conditions. 



CgHioOo = 2CH3-CHOHCOOH 



Glucose Lactic acid 



CoHioOg = CH3-CH2CH2COOH + 2CO2 + 2H2 



Glucose Butyric acid 



CgHioOg = 2CH3CH2OH + 2CO2 



Glucose Ethyl alcohol 



In the presence of oxygen, the sugar molecule is broken down, 

 through the lactic acid, acetaldehyde, and pyruvic acid stages, to 

 carbon dioxide and water, as shown by the following reactions: 



CeHiaOo = 2CH3-CO-COOH + 2H2 



Glucose Pyruvic acid 



CHs-CO-COOH + Ho = CHs-CHOH-COOH 



Pyruvic acid Lactic acid 



CHs-COCOOH + Ho = CH3CHO + Ho + CO2 



Pyruvic acid Acetaldehyde 



CH3CHO + Ho = CH3CH2OH 



Acetaldehyde Ethyl alcohol 



