| There has been growing interest to develop forage rice as a new feed resource for livestock in the world, and ensiling technique is becoming a common way to preserve fresh crop and grass. Many microbes, especially lactic acid bacteria(LAB), have been determined as important factors associated with grass and whole crop corn silages. These findings have contributed to a better management of silage and silage feeding, but complete information regarding the microbiota associate with silage of whole crop rice have not obtained. In this study, we employed both cultured-based and cultureindependent analyses to understand the microbial population including. Besides, we also examines the effect of LAB inoculants on the whole crop rice silage.One hundred and twenty-six strains were isolated and screened from whole crop rice silage prepared using a small-scale fermentation system, and 99 of these isolates were considered to be LAB based on their Gram-positive and catalase-negative morphology and the production of most of their metabolic products as lactic acid. These isolates were divided into eight groups(A-H) on the basis of their morphological and biochemical characteristics. The Group A to H strains were identified as Lactobacillus(L.) plantarum subsp. plantarum(species ratio: 8.1%), L. casei(5.1%), Leuconostoc(Ln.) pseudomesenteroides(11.1%), Pediococcus(P.) pentosaceus(24.2%), Enterococcus(E.) mundtii(12.1%), Lactococcus(Lc.) garvieae(15.2%), E. faecium(9.1%) and Lc. lactis subsp. lactis(15.2%) based on sequence analyses of their 16 S rRNA and recA genes. P. pentosaceus was the most abundant member of the LAB population in the paddy rice silage. A selected strain, namely L. casei R 465, was found to be able to grow under low pH conditions and to improve the silage quality with low pH and a relatively high content of lactic acid. This study demonstrated that forage paddy rice silage contains abundant LAB species and its silage can be well preserved by inoculation with LAB, and that strain R 465 can be a potentially excellent inoculant for whole crop rice silage.The effect of cellulase and lactic acid bacteria(LAB) on fermentation quality and chemical composition of rice straw silage was determined. Silages were prepared using a small-scale fermentation system and the moisture level was adjusted to 60% of fresh matter(FM) with deionized water. Treatments were designed as: control silage without additives, LAB inoculant R 465(Lactobacillus casi, 1.0 × 106 CFU g-1 of FM), commercial inoculant(Chikuso-1) FG 1(Lactobacillus plantarum, 1.0 × 106 CFU g-1 of FM), R 465 + cellulase and FG 1 + cellulase. The neutral detergent fiber(NDF), acid detergent fiber(ADF) and crude protein(CP) contents of the rice straw prior to ensiling were 76.93, 48.52 and 4.63% of dry matter(DM), respectively. After 30 d of storage, the silages treated with LAB and LAB + cellulase have a lower(P < 0.05) pH and higher(P < 0.05) lactic acid content than the control, and the coliform bacteria, yeast and mold were inhibited at the early stage of fermentation. Besides, silages treated with cellulase have lower(P < 0.05) values of ADF and NDF than the control. The results confirmed that addition of cellulase and LAB contributed to improving the fermentation quality of rice straw silage.The fermentation quality and bacterial community of whole crop rice silage stored in laboratory-scale silo and a bunker silo with different chop lengths inoculated L. buchneri were examined with culture-independent method. In the laboratory-scale silo, inoculated heterofermentative L. buchneri could inhibit the growth of Saccharomyces cerevisiae, and significantly improve the aerobic spoilage of whole crop rice silage after open. For bunker silo, whole crop rice was chopped into 6 mm, 11 mm, and 19 mm lengths by a newly developed harvester, and then stored in a bunker with Lactobacillus buchneri inoculation. Silages were stored for 8-9 months before sampling. Four samples were collected from each bunker silo: outer-upper, outer-lower, inner-upper and inner-lower. All bunker silos were preserved at pH ranging from 3.9 to 4.3. In bunker silos, higher levels of lactic acid were found for 6 and 11 mm than 19 mm silo, whereas the contents of acetic acid and propanediol were greater for 19 mm silo. Inoculated L. buchneri was detected in all samples, quantitative PCR(qPCR) revealed that copy number of L. buchneri can be achieved to around 108 CFU g-1 of FM in all samples. Band indicatives of L. acetotolerans and W. paramesenteroides were both detected in bunker silos of whole crop rice, although their distribution were not uniformly distributed.The selection of inoculant strains has not been systematic. LAB strains from different origins were isolated and used to select the best strains for ensiling whole crop rice. The LAB strains were inoculated into the extracted liquid obtained from fresh whole crop rice to evaluate the fermentation products. 11 LAB strains were selected for further experiments based on the highest products of lactic or acetic acid, including 1 strain of W. confusa, 2 of L. reuteri and 8 of L. plantarum. The API 50 CH fermentation experiment indicated that all of the selected 11 LAB strains utilised most of the carbohydrates. All the strains grew at temperatures between 10 and 45oC and at a pH of 3.5 to 4.5; however, L. reuteri F7 and F8 tolerated a pH as low as 3.0. All 11 LAB strains showed antibacterial activity against Listeria monocytogens, Escherichia coil, Salmonella sp. and Acetobacter pasteurianus; however, after excluding the effect of organic acids, only C13, F7 and F8 still exhibited antibacterial activity. The present study indicated that the selected 3 LAB strains could be used to prepare silages of whole crop rice silage, especially Lactobacillus reuteri F7 and F8. |
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