Enhanced viability of Lactobacillus reuteri for probiotics production in mixed solid-state fermentation in the presence of Bacillus subtilis

In order to develop a multi-microbe probiotic preparation of Lactobacillus reuteri G8-5 and Bacillus subtilis MA139 in solid-state fermentation, a series of parameters were optimized sequentially in shake flask culture. The effect of supplementation of B. subtilis MA139 as starters on the viability of L. reuteri G8-5 was also explored. The results showed that the optimized process was as follows: water content, 50 %; initial pH of diluted molasses, 6.5; inocula volume, 2 %; flask dry contents, 30～35 g/250 g without sterilization; and fermentation time, 2 days. The multi-microbial preparations finally provided the maximum concentration of Lactobacillus of about 9.01?±?0.15 log CFU/g and spores of Bacillus of about 10.30?±?0.08 log CFU/g. Compared with pure fermentation of L. reuteri G8-5, significantly high viable cells, low value of pH, and reducing sugar in solid substrates were achieved in mixed fermentation in the presence of B. subtilis MA139 (P?<?0.05). Meanwhile, the mixed fermentation showed the significantly higher antimicrobial activity against E. coli K88 (P?<?0.05). Based on the overall results, the optimized process enhanced the production of multi-microbe probiotics in solid-state fermentation with low cost. Moreover, the viability of L. reuteri G8-5 could be significantly enhanced in the presence of B. subtilis MA139 in solid-state fermentation, which favored the production of probiotics for animal use.     

Identification of Anthraquinone-Degrading Bacteria in Soil Contaminated with Polycyclic Aromatic Hydrocarbons

Quinones and other oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are toxic and/or genotoxic compounds observed to be cocontaminants at PAH-contaminated sites, but their formation and fate in contaminated environmental systems have not been well studied. Anthracene-9,10-dione (anthraquinone) has been found in most PAH-contaminated soils and sediments that have been analyzed for oxy-PAHs. However, little is known about the biodegradation of oxy-PAHs, and no bacterial isolates have been described that are capable of growing on or degrading anthraquinone. PAH-degrading Mycobacterium spp. are the only organisms that have been investigated to date for metabolism of a PAH quinone, 4,5-pyrenequinone. We utilized DNA-based stable-isotope probing (SIP) with [U-¹³C]anthraquinone to identify bacteria associated with anthraquinone degradation in PAH-contaminated soil from a former manufactured-gas plant site both before and after treatment in a laboratory-scale bioreactor. SIP with [U-¹³C]anthracene was also performed to assess whether bacteria capable of growing on anthracene are the same as those identified to grow on anthraquinone. Organisms closely related to Sphingomonas were the most predominant among the organisms associated with anthraquinone degradation in bioreactor-treated soil, while organisms in the genus Phenylobacterium comprised the majority of anthraquinone degraders in the untreated soil. Bacteria associated with anthracene degradation differed from those responsible for anthraquinone degradation. These results suggest that Sphingomonas and Phenylobacterium species are associated with anthraquinone degradation and that anthracene-degrading organisms may not possess mechanisms to grow on anthraquinone.     

A study of the genetic polymorphism of human inter-alpha-trypsin-inhibitor (ITI) in the Han population,Chengdu, China

Phenotypes of inter-alpha-trypsin-inhibitor (ITI) have been determined by isoelectric focusing on polyacrylamide gels followed by immunofixation. The phenotype frequencies of ITI in the Han population in Chengdu, P. R. China have been investigated using this method. In addition, family studies have been conducted in 21 families. The results show that ITI is polymorphic in the Han population in Chengdu, China. The allele frequencies are as follows: ITI*1 = 0.5763. ITI*2 = 0.4107, ITI*3 = 0.0130. ITI is thus a new and promising genetic marker that can be used in the field of forensic haematogenetics.     

Parasitism ofAphis gossypii (Homoptera: Aphididae) byAllothrombium pulvinum larvae (Acari: Trombidiidae) in cotton fields: spatial dispersion and density dependence

Spatial aspects of the interaction between the aphid host,Aphis gossypii, and its parasite,Allo-thrombium pulvinum larvae, on cotton plants were examined in seven fields in China. For both the host and the parasite, sample variance increased with the mean according to Taylor's power law, which explained a substantial proportion (84–97%) of the variation in the data. Although both the host and parasite showed aggregated distribution on cotton plants, the host aphids aggregated more strongly than the parasites. The host dispersion pattern was not significantly affected by the presence of parasites. Increasing the spatial scales of observation from individual plot to the entire field also had no significant effects on host and parasite dispersion patterns. Parasites aggregated in cotton plants with higher aphid densities in five out of the seventeen samples. Spatial patterns of parasitism were mostly host density-independent (71% of the samples) and sometimes inversely density-dependent (29% of the sample). The processes underlying these patterns were discussed.     

QUANTITATIVE VARIATION OF ECDYSTEROIDS OF IXODID TICKS

Abstract  In order to explore the role of ecdysteroids in development and reproduction of ixodid ticks, we studied the quantitative variation of ecdysteroids in the hemolymph, synganglion, ovary and whole body of the female ixodid ticks, Dermacentor niveus and Haemaphysalis longicornis , before and after engorgement and oviposition by HPLC and RIA. The ecdysteroid content in eggs of these ticks was determined by HPLC. The results indicated that before engorgement the quantitative variation of ecdysteroids in the whole female body was not significant, but their levels increased rapidly after engorgement. The ecdysteroid titer in hemolymph was peaked on the 5th day after engorgement, which was one day prior to oviposition. It may be regarded as a singnal of oviposition. In the synganglion the peak of ecdysteroid level occurred also on the 5th day after engorgement. This is coincident with the secretory activity of neurosecretory cells of synganglion. From the 3rd day after engorgement until oviposition the ecdysteroid level in the ovary increased rapidly. Ecdysteroids were detected in eggs of H. longicornis too. They stem from ovary and accumulated with the process of embryonic development.     

山岳型乡村旅游地“三生”空间演变及优化——德庆金林水乡的案例实证

以德庆县金林水乡为例,采用参与式观察和空间统计法,选取2000、2008年和2018年3个时段分析旅游发展对山岳型乡村旅游地"三生"空间的影响,并探讨了金林水乡"三生"空间的发展瓶颈及优化路径。研究发现:(1)旅游开发前,金林水乡土地结构与用地功能单一且呈片状分布;村落呈现传统乡村风貌,基础设施不健全;空间形态变化稳定,扩张缓慢。(2)旅游开发后,土地利用类型多样化,出现新型复合用地;土地功能利用复杂化,以服务旅游业为主;村庄景观风貌现代化,生活空间更加宜居。(3)旅游开发前后对比可得,土地平面占地规模化,空间用地以居民点为核心,呈圈层状向外围扩张;生产-生活-生态空间相互转化,乡村聚落重构特征较为显著;村落景观风貌的变化较大,呈现城镇化趋势。(4)金林水乡"三生"空间演化与旅游发展存在的问题表现在生产用地效率不高,生活用地质量较低,生态空间不断萎缩,在旅游产业发展上表现为旅游产品单一且缺乏创新,旅游服务功能不完善等。为此从生活空间的提质、生产空间增效、生态空间保护、旅游产业创新以及土地利用五方面提出优化建议。