In an extension of an earlier study of the formation of a mixture of m
ethane, propane and carbon dioxide in the biodegradation of solvent-ex
tracted elephant grass lignocellulose using pure microorganism culture
s unextracted (crude) elephant grass stalk was used. The effects of mi
xed microorganisms (instead of pure cultures), potato dextrose agar (P
DA) and nutrients (PO43- SO42-, urea, D,L-asparagine) were studied. In
addition, the effectiveness of mixed microorganisms harnessed directl
y from the air on substrate samples was also investigated. The results
showed good correlation with those of the earlier study. The extent o
f biogas formation was found to depend on the concentration of elephan
t grass and to be first-order with respect to the latter. PDA and all
the nutrients enhanced biogas formation. Urea was most effective at th
e lower concentrations. Systems with microorganisms harnessed directly
on the substrate by prior exposure to air degraded practically as eff
iciently as those treated with mixed cultures.