细菌技术在水泥基材料中的研究现状及展望

介绍了细菌技术胶凝复合材料的研究进展，例如细菌诱导碳酸钙沉淀的机理，细菌在水泥基复合材料中的应用方法，细菌对水泥基材料机械性能、耐久性的影响，以及成本效益分析等。概述了在建筑中应用细菌技术的水泥基复合材料的机遇和挑战。     

固态发酵产酶反应中体系传热传质行为分析

固态发酵是纤维素类生物质转化的有效途径,具有用水量少、容积产率高等优点。固态发酵生产纤维素酶一般是液态发酵酶产量的近3倍,可大幅降低酶的生产成本。在固态发酵过程,微生物在缺水环境中生长,发酵底物和接种物之间存在异质性,导致发酵热量分布不均匀、发酵过程氧气与中间产物不易扩散等问题。基于此,重点对固态发酵反应中体系传热传质方式及其影响因素进行了分析,并探讨其强化方法。根据传热方式,总结了发酵罐适用的导热微分方程及传热模拟方法,并分析气泡和颗粒基质中的传质过程及其限速步骤以及解决传质限速的途径。反应体系传热传质机理研究可促进固态发酵技术产业化应用进程。该研究可为有机废弃物固态发酵技术研究及应用提供一定的理论和技术支持。     

Oxidative capacity and hemolytic activity of settled dust from moisture‐damaged schools

Exposure to moisture‐damaged indoor environments is associated with adverse respiratory health effects, but responsible factors remain unidentified. In order to explore possible mechanisms behind these effects, the oxidative capacity and hemolytic activity of settled dust samples (n = 25) collected from moisture‐damaged and non‐damaged schools in Spain, the Netherlands, and Finland were evaluated and matched against the microbial content of the sample. Oxidative capacity was determined with plasmid scission assay and hemolytic activity by assessing the damage to isolated human red blood cells. The microbial content of the samples was measured with quantitative PCR assays for selected microbial groups and by analyzing the cell wall markers ergosterol, muramic acid, endotoxins, and glucans. The moisture observations in the schools were associated with some of the microbial components in the dust, and microbial determinants grouped together increased the oxidative capacity. Oxidative capacity was also affected by particle concentration and country of origin. Two out of 14 studied dust samples from moisture‐damaged schools demonstrated some hemolytic activity. The results indicate that the microbial component connected with moisture damage is associated with increased oxidative stress and that hemolysis should be studied further as one possible mechanism contributing to the adverse health effects of moisture‐damaged buildings.     

Effect of electrode spacing on the performance of microbial fuel cells with a honeycomb flow straightener

Microbial fuel cells (MFCs) are bioelectrochemical transducers that can be used to produce electrical power under the activity of microbes during the wastewater treatment processes. In the present study, the electrode spacing was considered as a parameter to investigate the influence on the performance of MFCs. The electrode spacing was defined as the distance of the anode electrode plate to the polymer exchange membrane in the MFCs. Three values were set at 0.0, 3.0, and 6.0 cm, respectively. In addition, a flow device, like a honeycomb type flow straightener, was introduced and implemented in the anode chamber for creating a uniform flow. The inner diameter of the honeycomb was 0.7 cm. Results showed that a higher limiting current density with 4108.7 mA/m² and a lower resistance with 2.51 Ω can be found in the case of the 0.0 cm electrode spacing. These results also indicated that the shorter electrode spacing with flow straightener devices would improve the performance of MFCs, leading to lower internal resistance and higher power density. In addition, the scanning electron microscopy was employed to analyze the biofilm thickness for MFCs with different electrode spacing. It was also found that the biofilm thickness with 0 cm electrode spacing was larger than the other two cases, leading to a lower internal resistance in the MFCs.     

Psychobiotics: A new approach for treating mental illness?

Gut microbiomes may have a significant impact on mood and cognition, which is leading experts towards a new frontier in neuroscience. Studies have shown that increase in the amount of good bacteria in the gut can curb inflammation and cortisol level, reduces symptoms of depression and anxiety, lowers stress reactivity, improves memory and even lessens neuroticism and social anxiety. This shows that, probably the beneficial gut bacteria or probiotics function mechanistically as delivery vehicles for neuroactive compounds. Thus, a psychobiotic is a live organism, when ingested in adequate amounts, produces a health benefit in patients suffering from psychiatric illness. Study of these novel class of probiotics may open up the possibility of rearrangement of intestinal microbiota for effective management of various psychiatric disorders.     

Active dry Saccharomyces cerevisiae can alleviate the effect of subacute ruminal acidosis in lactating dairy cows

The objective of the study was to determine the effect of active dry Saccharomyces cerevisiae (ADSC) supplementation on dry matter intake, milk yield, milk components, ruminal pH, and microbial community during a dietary regimen that leads to subacute ruminal acidosis (SARA). Sixteen multiparous, rumen-cannulated lactating Holstein cows were randomly assigned to 1 of 2 dietary treatments that included ADSC (Biomate; AB Vista, Marlborough, UK; 8 × 10¹⁰ cfu/head per day) or control. During wk 1 to 6, all cows received a high-forage (HF) diet (77:23, forage:concentrate). Cows were then abruptly switched during wk 7 to a high-grain (HG) diet (49:51, forage:concentrate) and remained on the HG until the end of wk 10. Feed intake and milk yields were recorded daily. Ruminal pH was recorded continuously using an indwelling system for 1 to 2 d per week during the pre-experimental phase, and wk 6, 7, and 10. Ruminal digesta samples were collected at the end of the experiment and analyzed for relative change in microbial communities using real-time quantitative PCR. Cows were considered to have SARA if the duration below pH 5.6 was ≥300 min/d. Ruminal pH during wk 6 (HF plateau) was not different across treatments (15 ± 46 min/d at pH <5.6). The dietary regimen successfully induced SARA during wk 7 (transition from HF to HG diet), and ruminal pH (551 ± 46 min/d at pH <5.6) was not different across treatments. However, cows receiving ADSC had an improved ruminal pH (122 ± 57 vs. 321 ± 53 min/d at pH <5.6) during wk 10 (HG plateau) compared with control. Additionally, cows receiving ADSC had a better dry matter intake (23.3 ± 0.66 vs. 21.6 ± 0.61 kg/d) and 4% fat-corrected milk yield (29.6 ± 1.2 vs. 26.5 ± 1.2 kg/d) than control cows during the HG phase (wk 8 to 10). During HG feeding, cows receiving ADSC had greater total volatile fatty acid and propionate concentrations (175 ± 7.5 vs. 154 ± 7.5 and 117 ± 6.1 vs. 94 ± 5.7 mM for ADSC and control, respectively) and lower acetate:propionate ratio (0.26 ± 0.5 vs. 0.36 ± 0.05 for ADSC and control, respectively). Microbial analyses conducted on samples collected during wk 10 showed that cows supplemented with S. cerevisiae had a 9-fold, 2-fold, 6-fold, 1.3-fold, and 8-fold increase in S. cerevisiae, Fibrobacter succinogenes, Anaerovibrio lipolytica, Ruminococcus albus, and anaerobic fungi, respectively, which suggested an increase in cellulolytic microbes within the rumen. Cows supplemented with ADSC had 2.2-fold reduction in Prevotella albensis, which is a gram-negative bacterium predominant during SARA. Prevotella spp. are suggested to be an important source of lipopolysaccharide responsible for inflammation within the rumen. Cows supplemented with ADSC had a 2.3-fold increase in Streptococcus bovis and a 12-fold reduction in Megasphaera elsdenii. The reduction in M. elsdenii may reflect lower concentration of lactic acid within the rumen for ADSC cows. In conclusion, ADSC supplementation to dairy cows was demonstrated to alleviate the condition of SARA caused by abrupt dietary changes from HF to HG, and can potentially improve rumen function, as indicated by greater numbers of cellulolytic microorganisms within the rumen.     

己酸菌液在浓香型白酒生产中的应用

采用公司自制的己酸菌功能茵液，应用于窖池养护、回窖发酵、串蒸提香以及制备调味酒等方面，并对应用结果进行了分析总结。结果表明，利用己酸菌功能茵液进行窖池的养护及其微生物复壮，能改善窖池，提高酒质；应用于回窖发酵、串蒸提香、调味酒生产等能明显提高产酒质量，增加经济效益。     

库存环境对羽绒填充物微生物影响的探讨

本文从重庆、沈阳、上海三地分别抽取库存一年、两年、三年的羽绒服,根据GB/T 14272《羽绒服装》进行微生物检测,探讨各地环境、库存时间对羽绒服微生物的影响,为企业改善羽绒制品的仓储条件提供依据。     

Nonthermal plasma for pesticide and microbial elimination on fruits and vegetables: an overview

Nonthermal plasma (NTP) is defined in terms of partly ionised gas which overall temperature is quite low because the stored energy is mostly in free electrons. Applications of NTP have been expanded to new areas of food applications such as the microbial inactivation and also the elimination of pesticide and toxic chemical residues in food such as fruits and vegetables while nutritional content and key characteristics are still preserved. Plasma treatment has successfully decreased the concentrations of pesticides by about 45‐71%. In this article, NTP technologies as well as investigations about applying of NTP for removing pesticide residues and improving microbial safety in fresh produce are described. Potential applications of NTP in food processing together with some of their challenges and limitations are also discussed.     

Production of polyhydroxy fatty acids from linoleic acid by Clavibacter sp. ALA2

Hydroxy fatty acids are important industrial materials. We isolated a microbial culture, Clavibacter sp. ALA2, which converts linoleic acid to many polyhydroxy fatty acids. Structures of the products were determined as: 12,13,17-trihydroxy-9(Z)-octadecenoic (THOA, main product), 12-[5-ethyl-2-tetrahydrofuranyl]-7,12-dihydroxy-9(Z)-dodecenoic (ETDDA), and 12-[5-ethyl-2-tetrahydrofuranyl]-12-hydroxy-9(Z)-dodecenoic (ETHDA) acid. The yield of THOA was 25% and the relative amount of the products were THOA/ETDDA/ETHDA =9:1.3:1. The structures of the hydroxy unsaturated fatty acids resemble those of plant self-defense substances.