G P Kalle
Articles written in Journal of Biosciences
Volume 5 Issue 1 March 1983 pp 43-52
Synthesis of dipicolinic acid in
Volume 5 Issue 4 December 1983 pp 321-330
Dipicolinic acid synthesis in
Volume 6 Issue 3 September 1984 pp 315-324
The composition of volatile fatty acids in the biogas digester based on cattle manure as substrate and stabilised at 25°C showed that it contained 87–88% branched chain fatty acids, comprising of isobutyric and isovaleric acids, in comparison to 38 % observed in the digester operating at 35°C.
Mixed cellulolytic cultures equilibrated at 25°C (C-25) and 35‡C (C-35) showed similar properties, but rates of hydrolysis were three times higher than that observed in a standard biogas digester. The proportion of isobutyric and isovaleric were drastically reduced when C-25 was grown with glucose or filter paper as substrates. The volatile fatty acids recovered from C-25 (at 25°C) inhibited growth of methanogens on acetate, whereas that from C-35 was not inhibitory. The inhibitory effects were due to the branched chain fatty acids and were observed with isobutyric acid at concentrations as low as 50 ppm.
Addition of another micro-organism
Volume 9 Issue 3-4 December 1985 pp 137-144
Biogas production has been shown to be inhibited by branched chain fatty acids (isobutyric, isovaleric) produced in the digester by cellulolytic organisms. Performance of these mixed cellulolytic cultures isolated at 25°C (C25) and at 35° (C35) in a batch digester using cattle manure confirmed that C35, which forms mainly straight chain fatty acids from cellulose was more suitable for use as an inoculum than C25 which formed predominantly branched chain fatty acids. Reconstitution of cellulolytic culture C35 and mixed methanogens M35 almost doubled both the amount and rate of methane production. Cellulolytic culture was useful in pretreatment of water hyacinth prior to its use as a substrate for methane generation A method for preservation and transportation of mixed cellulolytic culture for use as an inoculum in the digester is described.
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