Isolation and identification of symbiotic bacteria from the skin, mouth, and rectum of wild and captive tree shrews

Endosymbionts influence many aspects of their hosts’ health conditions, including physiology, development, immunity, metabolism, etc. Tree shrews(Tupaia belangeri chinensis) have attracted increasing attention in modeling human diseases and therapeutic responses due to their close relationship with primates. To clarify the situation of symbiotic bacteria from their body surface, oral cavity, and anus, 12 wild and 12 the third generation of captive tree shrews were examined. Based on morphological and cultural characteristics, physiological and biochemical tests, as well as the 16 S rDNA full sequence analysis, 12 bacteria strains were isolated and identified from the wild tree shrews: body surface: Bacillus subtilis(detection rate 42%), Pseudomonas aeruginosa(25%), Staphlococcus aureus(33%), S. Epidermidis(75%), Micrococcus luteus(25%), Kurthia gibsonii(17%); oral cavity: Neisseria mucosa(58%), Streptococcus pneumonia(17%); anus: Enterococcus faecalis(17%), Lactococus lactis(33%), Escherichia coli(92%), Salmonella typhosa(17%); whereas, four were indentified from the third generation captive tree shrews: body surface: S. epidermidis(75%); oral cavity: N.mucosa(67%); anus: L. lactis(33%), E. coli(100%). These results indicate that S. epidermidis, N. mucosa, L. lactis and E. coli were major bacteria in tree shrews, whereas, S. aureus, M. luteus, K. gibsonii, E. faecalis and S. typhosa were species-specific flora. This study facilitates the future use of tree shrews as a standard experimental animal and improves our understanding of the relationship between endosymbionts and their hosts.

Chemical Composition and in Vitro Antibacterial Activity of the Leaf Essential Oil of Mentha officinalis from Rwanda

The search for new prototype drugs to combat infection is an absolute necessity and in this regard plant essential oils may offer great potential and hope. In this investigation, the essential oil of the leaves ofMentha officinalis grown in Rwanda was extracted by hydrodistillation method and analyzed by gas chromatography （GC） and gas chromatography coupled with mass spectrometry （GC-MS）. The disc diffusion method was used to evaluate in vitro the zone of bacterial growth inhibition at various concentrations of the oil for five bacterial strains： Escherichia coli, Bacillus aureus, Streptococcus lactis, Staphylococcus aureus and Salmonella typhimurium. The results of this study revealed many components among which the major components were menthol （80.79%）, menthone （4.906%）, isomenthone （3.5%）, piperitone （2.56%）, and methyl acetate （2.2%）. After 7 days of incubation on PCA medium, the growth of Escherichia coli, Bacillus aureus, Streptococcus lactis and Staphylococcus aureus was totally inhibited at an average diameter of 19 mm, 32 mm, 50 mm and 30 mm respectively by a medium concentration of 30 μm/disc ofM. officinalis oil. Quite the reverse, this investigation by a bioassay showed that the essential oil ofM. officinalis has no effect on Salmonella typhimurium. The obtained results in the present study indicate the possibility of exploiting the essential oil ofM. officinalis to combat so many infectious human diseases in Rwanda. However, further investigations are required to make the medical exploitation of this plant successful.

Antibacterial Screening of Fifteen Cameroonian Medicinal Plants against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi

Multi-drug resistant microbial infections caused by Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi represent a critical public health issue worldwide. Plant-derived agents are credible sources for search and development of alternative antimicrobials to fight these infections. This study describes the in-vitro antibacterial activity of plants extracts from 15 medicinal plants of the Cameroonian pharmacopeia against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi. Plants selected based on their ethnopharmacological uses were extracted by either maceration or decoction using distilled water, ethanol, methanol and ethylacetate. The afforded extracts were phytochemically screened for bioactive secondary metabolites. The microdilution method was used to assess the antibacterial activity. The two promising extracts were tested in combination using the cbeckboard technique. Eighty one extracts showed antibacterial activity with eight having minimum inhibitory concentrations below 2.5 mg/mL. Results from combination assays with extracts from Terminalia catappa and Gnidia glauca leaves showed synergistic effect against Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi and additive effect against Staphylococcus aureus. These extracts mainly contained saponins, tannins, glucosides, phenols, triterpenes and anthraquinones. These results support the ethnobotanical claims and indicate further directions for the investigation of plants extracts to develop alternative drugs against multi-resistant bacteria.

Use of Cladophora glomerata Extract against Multidrug Resistant Bacterial Pathogens

The antibacterial effect of the crude methanol extracts and purified fractions of Ctadophora glomerata （Linnaeus） Kutzing （Cladophoraceae） against multidrug resistant human pathogen were investigated. The test bacterial strains were Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus faecalis, Escherichia coli and S. typhimurium. Ethanol extract （0.5 mg/mL） of Cladophora glomerata inhibited growth of all the test organisms. Primary detection of active compounds showed that maeroalgae （Cladophora glomerata） containing flavonoids, alkaloids, phenols and tannins. Gas Chromatography-Mass Spectrometry was used to know the compounds which responsible of antibacterial activity and they were g-Pentadecanone that was found to be a major compound （42.67%） followed by 8-Octadecanone （22.43%） and Salicylic acid （20.04%） in addition to 10-hexadecaden （8.01%）. These findings suggest the possibility of using the Cladophora glomerata as a novel source of natural antimicrobial agents in pharmaceutical industries.

瞿髯诗〔卷上〕

我校《教学与研究》创刊之际,裨得有关教授专家大力支持。夏承焘教授不仅遥承惠诺,不远数千里,寄来佳作《瞿髯诗》油印稿一册,又复赐书刊名题字。夏老已臻八十高龄,于诗词创作研究素负盛名。

雨碎江南

梦中的江南,总是带着淡淡的烟水寒色,似斟在琉璃杯中清浅的佳酿。蒙蒙的细雨,依旧无声无息,编织着暮雨中的江南。风有酒的气味,雨有酒的气味,小桥流水人家亦有酒的气味。轻风拂面,青石巷中悠悠而过的行人,也闻到了江南的气味。古色古香的江南啊,似是被时间遗忘,守着那一片净土,远离了红尘喧嚣,牵引着谁的相思?暮春时节,落花天,撑一把秦风汉月的油纸伞.