Selection of bacteria for liquid biofertilizer production from solid waste

Abstract

Twelve isolates of bacteria which could produce cellulase, protease and lipase, were screened from already identified bacteria, soil around food waste dumping area, soil around hot spring area from Sankampang, Chiang Mai, Thailand, decomposed vegetables and compost from The Royal Project, Chitralada Palace. The selected bacteria were identified as 5 isolates of Bacillus cereus, 1 isolate of Bacillus subtilis, 4 isolates of Bacillus coagulans, 1 isolate of Serratia marcescens and 1 isolate of Pseudomonas aeruginosa. When the enzyme activities were detected, the bacteria isolates with the highest activities of each enzyme were selected for the experimental production of liquid biofertilizer from the solid waste. The result from the antagonistic test revealed that these bacteria could use together without inhibiting each other and ready for the biofertilizer production. The solid wastes were sampled from home food waste and the synthetic waste composed of the leftover from vegetables, animals and used oil in the ratio of 1:1:1 by weight. The biofertilizer consisted of 6 pots as follows: pot 1; home food waste, pot 2; home food waste with bacteria 12 isolates, pot 3; synthetic waste, pot 4; synthetic waste with bacteria 12 isolates, pot 5; autoclaved synthetic waste, pot 6; autoclaved synthetic waste with bacteria 12 isolates. After 30 days of composting, the properties of the product were examined and the followings were obtained: temperature = 28 ℃, pH = 7.5-8.5, moisture content = 80%, C/N ratio = 8.00-16.80 and nutritional values N, P, K; 1.40, 1.20, 1.23 gm% respectively. The liquid biofertilizer was later provided to the plants (Amaranthus viridis L.) for 30 days, after plantation. Then, plants were harvested and studied for the effect of growth by measuring the height and fresh weight. The tallest plant was 21.00 cm and fresh weight was 42.3 g in the group of plant receiving the liquid biofertilizer from autoclaved synthetic waste with isolated bacteria. From overall results, it was found that there were no differences among all groups of treated plants.