Yimin Cai

Lactobacillus paralimentarius sp. nov., isolated from sourdough

Six strains of lactic acid bacteria isolated from sourdough were characterized taxonomically. They were Gram-positive, catalase-negative, facultatively anaerobic rods that did not produce gas from glucose. Morphological and physiological data indicated that the strains belong to the genus Lactobacillus and they were similar to Lactobacillus alimentarius in phenotypic characteristics. These strains shared the same phenotypic characteristics and exhibited intragroup DNA homology values of over 89.8%, indicating that they comprised a single species. The G + C content of the DNA for the strains was 37.2-38.0 mol%. The 16S rRNA sequence of representative strain TB 1T was determined and aligned with that of other Lactobacillus species. This strain was placed in the genus Lactobacillus on the basis of phylogenetic analysis. L. alimentarius was the most closely related species in the phylogenetic tree and this species also showed the highest sequence homology value (96%) with strain TB 1T. DNA-DNA hybridization indicated that strain TB 1T did not belong to L. alimentarius. It is proposed that these strains are placed in the genus Lactobacillus as a new species, Lactobacillus paralimentarius sp. nov. The type strain of L. paralimentarius is TB 1T, which has been deposited in the Japan Collection of Microorganisms (JCM) as strain JCM 10415T.

Bifidobacterium lactis Meile et al. 1997 Is a Subjective Synonym of Bifidobacterium animalis (Mitsuoka 1969) Scardovi and Trovatelli 1974

Bifidobacterium lactis JCM 10602T (T = type strain) and Bifidobacterium animalis JCM 1190T were found to be phenotypically similar. These strains were subjected to investigation of their genetic relationships. The 16S rRNA sequence of B. animalis JCM 1190T was aligned with that of other Bifidobacterium species. B. animalis and B. lactis were the most closely related species in the phylogenetic tree and showed a high similarity in sequences (98.8%). The levels of DNA‐DNA hybridization between the type strains of B. lactis and B. animalis ranged from 85.5 to 92.3%, showing that they represent a single species. It is proposed that B. lactis should be considered as a junior subjective synonym of B. animalis.

Characteristics of lactic acid bacteria isolated from forage crops and their effects on silage fermentation

Enterococcus faecalis CA 6, E faecium CA 10, E casseliflavus CA 13, Weissella paramesenteroides CA 14, Leuconostoc pseudomesenteroides CA 17, Pediococcus pentosaceus CA 21, P acidilactici CA 25 and Lactobacilus plantarum CA 28 isolated from forage crops were characterised and their effects on silage fermentation were studied. Strains CA 6, CA 10 and CA 13 grew only at relatively high pH (above 5.0), while strains CA 21, CA 25 and CA 28 were able to grow at pH values below 4.0. Strain CA 25 grew at 50°C, but the others did not grow at above 45 °C. These strains were used as inoculants for perennial ryegrass silage ensiled at 25 or 45 °C. At 25 °C all strains significantly (P < 0.01) reduced the pH value and butyric acid content and greatly increased the lactic acid content compared with the control, particularly strains CA 21, CA 25 and CA 28. At 45°C strain CA 25 markedly improved the fermentation quality of silage, but the others did not. These silages had a lower lactic acid content and a higher proportion of L(+)- to total lactic acid than equivalent silages kept at 25 °C. The results confirmed that at 25 °C P pentosaceus CA 21, P acidilactici CA 25 and L plantarum CA 28 were the most effective, whereas at 45 °C only Pacidilactici CA 25 had a beneficial effect on silage fermentation quality.

Production of 3-hydroxypropionaldehyde in silage inoculated with Lactobacillus coryniformis plus glycerol.

We examined the production of an antimicrobial component, 3-hydroxypropionaldehyde (3-HPA), in laboratory-scale silage inoculated with Lactobacillus coryniformis strain 394, which ferments glycerol to 3-HPA. A modified colorimetric method that used an NaOH-treated blank and determined the absorption spectrum of the samples was employed to detect a 3-HPA-like component (HLC) that was assumed to be 3-HPA. Inoculation with Lb. coryniformis 394 plus glycerol in ensiling produced HLC at 10–460 ppm and contributed to inhibition of butyric fermentation and retardation of aerobic spoilage. HLC was considered to be 3-HPA from its absorption spectrum. These results suggest that the production of 3-HPA by Lb. coryniformis 394 is useful in ensiling and that the modified colorimetric method is effective to detect 3-HPA in silage.

Silage produces biofuel for local consumption

BackgroundIn the normal process of bioethanol production, biomass is transported to integrated large factories for degradation to sugar, fermentation, and recovery of ethanol by distillation. Biomass nutrient loss occurs during preservation and degradation. Our aim was to develop a decentralized ethanol production system appropriate for farm or co-operative level production that uses a solid-state fermentation method for producing bio-ethanol from whole crops, provides cattle feed, and produces no wastes. The idea is to incorporate traditional silage methods with simultaneous saccharification and fermentation. Harvested, fresh biomass is ensiled with biomass-degrading enzymes and yeast. Multiple parallel reactions for biomass degradation and ethanol and lactic acid production are induced in solid culture in hermetically sealed containers at a ranch. After fermentation, ethanol is collected on site from the vapor from heated fermented products.ResultsThe parallel reactions of simultaneous saccharification and fermentation were induced efficiently in the model fermentation system. In a laboratory-scale feasibility study of the process, 250 g of freshly harvested forage rice with 62% moisture was treated with 0.86 filter paper units/g dry matter (DM) of cellulase and 0.32 U/g DM of glucoamylase. After 20 days of incubation at 28°C, 6.4 wt.% of ethanol in fresh matter (equivalent to 169 g/kg DM) was produced. When the 46 wt.% moisture was gathered as vapor from the fermented product, 74% of the produced ethanol was collected. Organic cellular contents (such as the amylase and pronase degradable fractions) were decreased by 63% and organic cell wall (fiber) content by 7% compared to silage prepared from the same material.ConclusionsWe confirmed that efficient ethanol production is induced in nonsterilized whole rice plants in a laboratory-scale solid-state fermentation system. For practical use of the method, further study is needed to scale-up the fermentation volume, develop an efficient ethanol recovery method, and evaluate the fermentation residue as an actual cattle feed.

The effect of inoculation and additives on D(-)- and L(+)-lactic acid production and fermentation quality of guineagrass (Panicum maximum Jacq) silage.

Two experiments were carried out to study the influence of storage time, glucose and urea additions (Experiment 1) and lactic acid bacteria inoculation with and without glucose addition (Experiment 2) on the production oflactate isomers and fermentation quality of guineagrass (Panicum maximum Jacq) silage. All silages in both experiments were well preserved, as indicated by lower pH and little or no butyric acid. In Experiment 1, addition of glucose or urea did not significantly affect the pH of silages (P>0.05). Urea addition tended to reduce acetic acid content and greatly increased NH 3 -N content. L(+)-lactic acid was produced predominantly in the first 3 days of ensiling, but D(-)-lactic acid increased gradually until 1 month after ensiling. Thereafter all silages became stable. In Experiment 2, inoculation of Lactobacillus casei or L rhamnosus with or without glucose reduced D(-)-lactic acid and increased L(+)-lactic acid of silages. The proportions of L(+)-lactic acid in these silages were higher than 80% of total lactic acid. L plantarum alone or in combination with glucose promoted D(-)-lactic acid production and decreased the proportion of L(+)-lactic acid. Glucose addition alone tended to reduce the proportion of L(+)-lactic acid in both experiments.