Novel bioconversion of wheat straw to bio-organic fertilizer in a solid-state bioreactor

In order to increase the eco-efficiency and overall availability of naturally renewable resource, the novel bioconversion of steam-exploded wheat straw to bio-organic fertilizer containing N(2)-fixer, P and K solubilizers was investigated. The conversion was performed in solid-state fermentation (SSF) with periodic air-forced pressure oscillation (PAPO). The results showed that SSF-PAPO was competitive with the conventional solid-state fermentation (cSSF) in biomass accumulation and wheat straw digestion. With solid-liquid ratio 1:3, microbial biomass production at 72 h was high up to 2 x 10(11) cfu g(-1), nearly twice as that in cSSF. The degradation rate of cellulose, hemicellulose and lignin after fermentation in SSF-PAPO reached 48.57 +/- 10.66, 84.77 +/- 2.75 and 2.15 +/- 10.11, respectively, which was greater than that of 29.30 +/- 10.28%, 33.47 +/- 4.85% and 0.53 +/- 9.07% in cSSF, correspondingly. The SSF-PAPO system displayed unique advantage, by a novel gas phase control strategy on gas concentration and heat gradient, on the bioconversion of wheat straw to the bio-organic fertilizer.