Straw incorporation is an important measure to improve soil fertility and soil acidification. However, fresh straw that is returned to the field cannot be decomposed in a short time. Accumulation of undecomposed straw in the soil changes humus composition and the C structure. An experiment was designed to evaluate the effects of decomposed straw on soil fertility and microbial communities. Soil samples were collected from a rice-rice-tobacco region in southwestern China (The rice was Hongyou No 7, which was a new variety applied in 2007 by the Honghe State Agricultural Science Institute,Yunnan province, China). (The tobacco was K326. K326 was an excellent variety which Imported from Northup King Seed Company (USA) to China in 1985). The soil was mixed with different kinds of straw and incubated in a greenhouse. The responses of the soil fertility, microbial diversity, and microbial population were analyzed after 0, 16, and 33 d of incubation. Overall, we found that (a) the soil organic matter and the organic C content of each humus component were significantly increased after 33 d of incubation. In addition, the condensation and oxidation degrees of the soil C structure were decreased. (b) Community dynamics changes in the soil were accompanied by changes of incubation times. (c) Decomposed straw incorporation could stimulate potentially beneficial microbial populations. (d) Decomposed straw incorporation with microbial agent application could be the best practice for the application of biofertilizers.
Polysaccharides derived from lactic acid bacteria (LAB) have widespread industrial applications owing to their excellent safety profile and numerous biological properties. The antioxidant activity of exopolysaccharides (EPS) offers defense against disease conditions caused by oxidative stress. Several genes and gene clusters are involved in the biosynthesis of EPS and the determination of their structures, which play an important role in modulating their antioxidant ability. Under conditions of oxidative stress, EPS are involved in the activation of the nonenzyme (Keap1-Nrf2-ARE) response pathway and enzyme antioxidant system. The antioxidant activity of EPS is further enhanced by the targeted alteration of their structures, as well as by chemical methods. Enzymatic modification is the most commonly used method, though physical and biomolecular methods are also frequently used. A detailed summary of the biosynthetic processes, antioxidant mechanisms, and modifications of LAB-derived EPS is presented in this paper, and their gene-structure−function relationship has also been explored.
In visual working memory (VWM) tasks, participants’ performances can be improved using dimension-based retro-cues, which direct internal attention to prioritize a particular dimension (e.g., color or orientation) of VWM representations during the maintenance stage after the stimuli disappear. This phenomenon is called the dimension-based retro-cue benefit (RCB). The present study investigated whether the dimension-based RCB requires sustained attention to prioritize information by inserting interference between the retro-cue and the test array to distract the sustained attention. The experiments tested the influence of perceptual or cognitive interference on dimension-based RCB when the interference appeared at the VWM maintenance stage or attentional deployment stage (Exp. 1: masks appeared at the VWM maintenance stage; Exp. 2: masks appeared at the attentional deployment stage; Exp.3: an odd-even interference task appeared at the VWM maintenance stage). We found that the dimension-based RCB was attenuated by perceptual interference (masks) or cognitive interference (odd-even interference task). Our results suggest that sustained attention is needed for effective prioritization of a particular dimension of VWM representations.
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