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Abstract: The distributions of microbial tetraether lipids, i.e. glycerol dialkyl glycerol tetraethers (GDGTs), were investigated in a variety of Chinese soils featured by a wide range of pH values in different climate zones. The bacterial branched GDGTs and archaeal isoprenoid GDGTs were found to be widely distributed in Chinese soils and their relative abundance was controlled primarily by soil pH. The bacterial bGDGTs usually dominate over archaeal iGDGTs in abundance when the soil pH is below 8.0. However, archaeal iGDGTs become dominant and the abundance of halophilic archaea characterized by GDGT V without cyclopentyl ring increases dramatically in the alkaline soil with pH greater than 8.0. The relative abundance of archaeal iGDGTs to bacterial bGDGTs was defined here as RAI index. The RAI index decreases with elevated soil pH and a linear correlation is found between them, indicating that the relative abundance of archaeal iGDGTs to bacterial bGDGTs increases with increased pH. The RAI index thus could be a novel proxy of the pH values of paleosol. The terrestrial input index, BIT (Branched and Isoprenoid Tetraethers Index), decreases with increased soil pH, suggesting that soil pH should be taken into consideration when the terrestrial contribution to marine sediments is estimated by BIT index. Moreover, the TEX86 index cannot be used to reconstruct sea surface temperature in the sediments featured by a large terrestrial input.

Abstract: In this study, cutinase production by Thermobifida fusca WSH03-11 was investigated with mixed short-chain organic acids as co-carbon sources to demonstrate the possibility of producing high value-added products from organic wastes. T. fusca WSH03-11 was cultured with different combinations of butyrate, acetate, and lactate with a purpose of increasing cutinase activity. The optimum proportion of butyrate, acetate, and lactate was 4:1:3. In batch cultivation, acetate and lactate were consumed quickly, while the consumption of butyrate was depressed in the presence of acetate with a concentration higher than 0.5 g/L. Based on these results, a two-stage batch and fed-batch cultivation strategy was proposed: a batch culture with acetate and lactate as the co-carbon sources in the first 10 h, and then a fed-batch culture with a constant butyrate feeding rate of 12 mL/h during 11~20 h. By this two-stage cultivation strategy, cutinase activity, dry cell weight, and consumption rate of butyrate were increased by 70%, 103.4%, and 4.3-fold, respectively, compared to those of the batch cultivation. These results provided a novel and efficient way to produce high value-added products from organic wastes.