Endophytic Bacillus strains isolated from alfalfa (Medicago sativa L.) seeds: enhancing the lifespan of Caenorhabditis elegans.

Medicago sativa L. (alfalfa) is an important forage crop throughout the world. Despite the abiotic nutritional components of alfalfa having been extensively studied, there is only limited information on alfalfa endophytes. In this study, thirteen endophytic bacteria were isolated from alfalfa seeds. Bacillus (76·9%) was the most abundant genus, followed by Enterobacter (15·4%), Brevibacterium (7·7%), Geobacillus (7·7%) and Staphylococcus (7·7%). Four of the 13 endophytic bacteria, including Bacillus amyloliquefaciens EnB-alf1, Bacillus subtilis EnB-alf3, EnB-alf5 and EnB-alf13, were capable of significantly extending the lifespan of Caenorhabditis elegans. In addition, B. amyloliquefaciens EnB-alf1 enhanced the resistance of C. elegans to thermal stress whereas B. subtilis EnB-alf3 enhanced the resistance to oxidative stress. Further studies demonstrated that the enhanced lifespan of the worm was depended on the function of DAF-2/DAF-16 and was associated with the colonization of strain in the worms' intestines when strain EnB-alf1 or strain EnB-alf3 was presented to the worms as food sources. Our results suggest that some endophytic Bacillus strains isolated from alfalfa are beneficial on C. elegans health. SIGNIFICANCE AND IMPACT OF THE STUDY: Medicago sativa L. (alfalfa) is an important forage crop throughout the world. Despite the abiotic nutritional components of alfalfa having been extensively studied, there is only limited information available on alfalfa endophytes. Beneficial bacteria residing in the host intestine have been shown to affect host longevity. However, there is limited information available on the functions of alfalfa seed endophytes to nematodes. In this study, four endophytic Bacillus strains isolated from alfalfa seeds were found to significantly extend the lifespan of Caenorhabditis elegans and enhance resistance to thermal and oxidative stress. Our results suggest that some endophytic Bacillus strains isolated from alfalfa seeds can promote good health in C. elegans.

Reduction of soy isoflavones by use of Escherichia coli whole-cell biocatalyst expressing isoflavone reductase under aerobic conditions.

UNLABELLED: Soy isoflavone metabolites are currently receiving much attention due to the stronger and wider bioactivities than that of isoflavones. Therefore, biosynthesis of isoflavone metabolites by isolated isoflavone biotransforming bacteria is important. However, the biosynthesis process must be under obligate anaerobic conditions due to the reduction reactions catalysed by isoflavone biotransforming bacteria. In this study, we cloned the daidzein and genistein reductase gene (dgr) from Slackia sp. AUH-JLC159. The recombinant Escherichia coli (E. coli) whole-cell was used for the first time as the biocatalyst for aerobic biosynthesis of dihydrodaidzein (DHD) and dihydrogenistein (DHG) from soy isoflavones daidzein and genistein. Our results indicated that the recombinant E. coli whole-cell was able to reduce daidzein and genistein to DHD and DHG under aerobic conditions, while the maximal concentration of the substrate daidzein or genistein that the E. coli whole-cell was able to convert efficiently was only 0·4 mmol l(-1) . Under the optimized conditions, the maximal concentration of daidzein or genistein that the E. coli whole-cell was able to convert efficiently was increased to 1·4 mmol l(-1) . Our results demonstrated that E. coli whole-cell is an efficient biocatalyst for biosynthesis of isoflavone metabolites under aerobic conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Soy isoflavone metabolites, which are more biologically active than their precursor isoflavones, are currently receiving much more attention. However, the non-natural isoflavone metabolites are synthesized or biosynthesized under obligate anaerobic conditions. Here, we describe a new approach to the reduction of soy isoflavones daidzein and genistein under aerobic conditions by use of the recombinant Escherichia coli whole-cell expressing isoflavone reductase. Our study provides the first evidence that isoflavone metabolites, such as dihydrodaidzein and dihydrogenistein, are able to be produced efficiently under aerobic conditions.

Enhanced biosynthesis of O-desmethylangolensin from daidzein by a novel oxygen-tolerant cock intestinal bacterium in the presence of atmospheric oxygen.

AIMS: To improve the oxygen-tolerant capability of a newly isolated anaerobic bacterium and to biosynthesize O-desmethylangolensin (O-Dma) from daidzein aerobically. METHODS AND RESULTS: After a long-term domestication process, an oxygen-tolerant bacterium, which we named Aeroto-AUH-JLC108, was derived from the newly isolated obligate anaerobic bacterium Clostridium sp. AUH-JLC108. Strain Aeroto-AUH-JLC108 differed from the natively anaerobic wild-type strain AUH-JLC108 by various characteristics, including a change in bacterial shape, biochemical characteristics and 16S rRNA gene sequences. Both the growth speed and the maximal optical density (OD) value of strain Aeroto-AUH-JLC108 grown aerobically were significantly increased compared to that of the wild-type strain grown anaerobically. The maximal concentration of the substrate daidzein that the oxygen-tolerant strain Aeroto-AUH-JLC108 grown aerobically was able to convert efficiently was 2.0 mmol l(-1) and 0.6 mmol l(-1) for strain AUH-JLC108 that was grown anaerobically. CONCLUSIONS: Strain Aeroto-AUH-JLC108 is a conditional oxygen-tolerant bacterium. The growth speed, bacterial growth mass and bioconversion capability of strain Aeroto-AUH-JLC108 grown aerobically was significantly increased compared to that of the wild-type strain AUH-JLC108 grown anaerobically. SIGNIFICANCE AND IMPACT OF THE STUDY: Strain Aeroto-AUH-JLC108 is the first reported pure culture responsible for the formation of O-Dma from daidzein in the presence of atmospheric oxygen.

Effect of short-term nutritional supplementation on hormone concentrations in ovarian follicular fluid and steroid regulating gene mRNA abundances in granulosa cells of ewes.

This study was conducted to investigate effects of short-term nutritional supplementation on concentrations of reproductive hormones in follicular fluid and on mRNA abundance in granulosa cells (GCs) during the luteal phase of ewes. Eighteen ewes were randomly assigned to treatment or control groups (n = 9, each group). All the ewes were subjected to estrous synchronization using a Controlled Intravaginal Releasing Device (CIDR). From the second to the eleventh day of estrous synchronization, ewes were fed a diet with a relatively greater (treatment group) or a maintenance (control group) energy content. Samples of follicular fluid and GCs were collected from antral follicles of estrous ewes after CIDR removal. The results indicate mean FSH concentration of fluid in small follicles and mean LH concentrations of fluid in large follicles of the ewes in the treatment group were greater (P < 0.05) than that of ewes in the control group. Follicular fluid E2 concentrations were directly related (P < 0.05) to follicular diameter. The ewes of the treatment group had greater (P < 0.05), compared with the control group, abundances of Follicle Stimulating Hormone Receptor (FSHR) in small and medium follicles, and (P<0.05) Luteinizing Hormone Receptor (LHR), Steroid Acute Regulatory Protein (STAR), cytochrome P450 (CYP17A1, CYP19A1) enzyme and Estrogen Receptor (ESR1) in large follicles. The results of this study provide evidence for a potential mechanism by which short-term nutritional supplementation improves follicular development possibly because of increased expression of steroid synthesis-regulating genes in large follicles.