Do woodlice (Isopoda: Oniscidea) produce endogenous cellulases?

In studies on digestive processes and microorganisms in the gut of the common woodlouse, Porcellio scaber (Isopoda: Oniscidea), we observed marked contradictions between the activity of cellulolytic enzymes and the number of microorganisms. The anterior hindgut exhibited the highest cellulolytic activity, but was characterized by low microbial counts. Due to the presence of endosymbiotic bacteria in the midgut lobes that appear to produce cellulases, we suggest that the cellulases that are active in the hindgut of woodlice are of endogenous origin. Received: 4 April 1997     

Earthworms disseminate a soil-borne plant pathogen,Fusarium oxysporum f. sp. raphani

Radish plants infested with a soil-borne plant pathogen, Fusarium oxysporum f. sp. raphani PEG-4, which is resistant to hygromycin B, were placed on the surface of a soil microcosm containing earthworms (Pheretima sp.). The earthworms ate the radish plants and scattered individual casts everywhere in the burrows. The fungal propagules were detected in the gut of the earthworms and in 26 out of 28 casts. These results suggested that the pathogen could survive passage through the alimentary canal of the earthworms and be disseminated anywhere earthworms wandered. The collected casts were incubated in a moist chamber at 28°C for 14 days, which resulted in a decline in the number of the propagules. The effects of the earthworms on the population dynamics of the pathogen were estimated. The earthworms seemed to cause a decline in total propagules of the pathogen in soil, although they expanded its distribution in soil.     

Yeasts associated with soil invertebrates

The hindgut of the diplopod Pachyiulus flavipes is inhabited by specific yeast populations. The yeast communities consist almost exclusively of ascomycetes, viz., Debaryomyces hansenii, Torulaspora delbrueckii, and Zygowilliopsis californica. Evidence is provided that the yeasts isolated from the gut can be considered symbionts that remain in a steady state under different feeding and rearing conditions.     

Evaluation of a novel animal milk oligosaccharide biosimilar: macronutrient digestibility and gastrointestinal tolerance,fecal metabolites,and fecal microbiota of healthy adult dogs and in vitro genotoxicity assays

Milk oligosaccharides (MO) are bioactive compounds in mammalian milk that provide health benefits to neonates beyond essential nutrients. GNU100, a novel animal MO biosimilar, was recently tested in vitro, with results showing beneficial shifts in microbiota and increased short-chain fatty acid (SCFA) production, but other effects of GNU100 were unknown. Three studies were conducted to evaluate the safety, palatability, and gastrointestinal (GI) tolerance of GNU100. In study 1, the mutagenic potential of GNU100 was tested using a bacterial reverse mutation assay and a mammalian cell micronucleus test. In study 2, palatability was assessed by comparing diets containing 0% vs. 1% GNU100 in 20 adult dogs. In study 3, 32 adult dogs were used in a completely randomized design to assess the safety and GI tolerance of GNU100 and explore utility. Following a 2-wk baseline, dogs were assigned to one of four treatments and fed for 26 wk: 0%, 0.5%, 1%, and 1.5% GNU100. On weeks 2, 4, and 26, fresh fecal samples were collected to measure stool quality, immunoglobulin A, and calprotectin, and blood samples were collected to measure serum chemistry, inflammatory markers, and hematology. On weeks 2 and 4, fresh fecal samples were collected to measure metabolites and microbiota. On week 4, total feces were collected to assess apparent total tract macronutrient digestibility. Although revertant numbers were greater compared with the solvent control in tester strain WP2uvrA(pKM101) in the presence of metabolic activation (S9) in the initial experiment, they remained below the threshold for a positive mutagenic response in follow-up confirmatory tests, supporting that GNU100 is not mutagenic. Similarly, no cytotoxicity or chromosome damage was observed in the cell micronucleus test. The palatability test showed that 1% GNU100 was strongly preferred (P < 0.05; 3.6:1 consumption ratio) over the control. In study 3, all dogs were healthy and had no signs of GI intolerance or illness. All diets were well accepted, and food intake, fecal characteristics, metabolite concentrations, and macronutrient digestibilities were not altered. GNU100 modulated fecal microbiota, increasing evenness and Catenibacterium, Megamonas, and Prevotella (SCFA producers) and reducing Collinsella. Overall, the results suggest that GNU100 is palatable and well-tolerated, causes no genotoxicity or adverse effects on health, and beneficially shifts the fecal microbiota, supporting the safety of GNU100 for the inclusion in canine diets.     

Dietary inclusion of multispecies probiotics to reduce the severity of post-weaning diarrhea caused by Escherichia coli F18+ in pigs

This study was aimed to determine the efficacy of multispecies probiotics in reducing the severity of post-weaning diarrhea caused by enterotoxigenic Escherichia coli (ETEC) F18⁺ on newly weaned pigs. Thirty-two pigs (16 barrows and 16 gilts, BW = 6.99 ± 0.33 kg) at 21 d of age were individually allotted in a randomized complete block design with 2 × 2 factorial arrangement of treatments. Pigs were selected from sows not infected previously and not vaccinated against ETEC. Pigs were fed experimental diets for 25 d based on 10 d phase 1 and 15 d phase 2. The factors were ETEC challenge (oral inoculation of saline solution or E. coli F18⁺ at 2 × 10⁹ CFU) and probiotics (none or multispecies probiotics 0.15% and 0.10% for phase 1 and 2, respectively). Body weight and feed intake were measured on d 5, 9, 13, 19, and 25. Fecal scores were measured daily. Blood samples were taken on d 19 and 24. On d 25, all pigs were euthanized to obtain samples of digesta, intestinal tissues, and spleen. The tumor necrosis factor alpha (TNFα), malondialdehyde (MDA), peptide YY (PYY), and neuropeptide Y (NPY) were measured in serum and intestinal tissue. Data were analyzed using the MIXED procedure of SAS. The fecal score of pigs was increased (P < 0.05) by ETEC challenge at the post–challenge period. The ETEC challenge decreased (P < 0.05) jejunal villus height and crypt depth, tended to increase (P = 0.056) jejunal TNFα, increased (P < 0.05) ileal crypt depth, and decreased (P < 0.05) serum NPY. The probiotics decreased (P < 0.05) serum TNFα, tended to reduce (P = 0.064) jejunal MDA, tended to increase (P = 0.092) serum PYY, and increased (P < 0.05) jejunal villus height, and especially villus height-to-crypt depth ratio in challenged pigs. Growth performance of pigs were not affected by ETEC challenge, whereas the probiotics increased (P < 0.05) ADG and ADFI and tended to increase (P = 0.069) G:F ratio. In conclusion, ETEC F18⁺ challenge caused diarrhea, intestinal inflammation and morphological damages without affecting the growth performance. The multispecies probiotics enhanced growth performance by reducing intestinal inflammation, oxidative stress, morphological damages.     

Gut microbiota—a positive contributor in the process of intermittent fasting-mediated obesity control

Historically, intermittent fasting (IF) has been considered as an effective strategy for controlling the weight of athletes before competition. Along with excellent insight into its application in various spaces by numerous studies, increasing IF-mediated positive effects have been reported, including anti-aging, neuroprotection, especially obesity control. Recently, the gut microbiota has been considered as an essential manipulator for host energy metabolism and its structure has been reported to be sensitive to dietary structure and habits, indicating that there is a potential and strong association between IF and gut microbiota. In this paper, we focus on the crosstalk between these symbionts and energy metabolism during IF which hold the promise to optimize host energy metabolism at various physical positions, including adipose tissue, liver and intestines, and further improve milieu internal homeostasis. Moreover, this paper also discusses the positive function of a potential recommendatory strain (Akkermansia muciniphila) based on the observational data for IF-mediated alternated pattern of gut microbiota and a hopefully regulatory pathway (circadian rhythm) for gut microbiota in IF-involved improvement on host energy metabolism. Finally, this review addresses the limitation and perspective originating from these studies, such as the association with tissue-specific bio-clock and single strain research, which may continuously reveal novel viewpoints and mechanisms to understand the energy metabolism and develop new strategies for treating obesity, diabetes, and metabolic disorders.     

包被肉桂油对1~21日龄肉鸡生长性能和回肠微生物区系的影响

为进一步探究肉桂油的应用效果,本试验在前期研究基础上探讨了饲粮中添加300 mg/kg包被肉桂油对肉鸡回肠菌群多样性和组成的影响。试验采用单因素设计,将132只1日龄科宝500肉鸡随机分成对照组和试验组,每个处理组6个重复,每个重复11只鸡（5只公鸡,6只母鸡）。对照组饲喂基础饲粮,试验组饲粮在基础饲粮中添加300 mg/kg包被肉桂油,试验期为21 d。结果显示,饲粮中添加300 mg/kg包被肉桂油对1~21日龄肉鸡生长性能无显著影响（P>0.05）。与对照组相比,试验组肉鸡21日龄回肠微生物的Shannon指数和Sobs指数显著增加（P<0.05）,Simpson指数显著降低（P<0.05）。两组回肠微生物共有的OTU数为133个,对照组和试验组独有的OTU数分别为4和135个。ANOSIM分析显示,肉鸡回肠微生物的组间差异大于组内差异（R=0.4896）且差异显著（P<0.05）。试验组回肠链球菌属相对丰度显著低于对照组（P<0.05）;两组回肠其他属细菌丰度差异均不显著（P>0.05）。综上所述,饲粮中添加300 mg/kg包被肉桂油有利于增加21日龄肉鸡回肠微生物多样性,降低链球菌属细菌的相对丰度。     

大熊猫粪便中微生物与寄生虫的宏转录组学分析

旨在探究大熊猫粪便中微生物组成以及耐药基因和寄生虫的真实情况。采集6只健康成年大熊猫的新鲜粪便,利用宏转录组学测序技术分析大熊猫粪便微生物组成及功能、耐药基因种类、丰度和寄生虫的组成,探讨优势细菌与耐药基因的相关性。结果表明,大熊猫粪便内微生物种类多样,包括细菌、真菌和病毒等,但以细菌为主。在门水平上,细菌类群中厚壁菌门（Firmicutes）和变形菌门（Proteobacteria）为优势菌门,在真菌菌门中担子菌门（Basidiomycota）、子囊菌门（Ascomycota）和毛霉亚门（Mucoromycota）相对丰度较高,雌性和雄性大熊猫粪便菌群丰度没有显著性差异（P>0.05）。Unigenes功能分析表明,大熊猫粪便微生物的功能主要涉及碳水化合物、氨基酸代谢等过程。在大熊猫粪便中共检测出25大类、304种耐药基因,其中,外排泵类基因的种类最多、相对丰度最高。此外,在大熊猫粪便中共发现63属126种寄生虫,寄生虫种包括线虫、绦虫和吸虫,其中,线虫为优势虫种。通过相关性分析发现,链球菌属（Streptococcus）、埃希杆菌属（Escherichia）、肠球菌属（Enterococcus）、苏黎世杆菌属（Turicibacter）与外排泵类、喹诺酮类、四环素类、糖肽类、多肽类和磺胺类耐药基因呈显著正相关性（P<0.05）。本研究从宏转录组水平揭示了大熊猫粪便中微生物、耐药基因组成以及寄生虫种类,对大熊猫微生物相关疾病和寄生虫病防控具有重要意义。