Regular Consumption of Biovalorized Okara-Containing Biscuit Improves Circulating Short-Chain Fatty Acids and Fecal Bile Acids Concentrations by Modulating the Gut Microbiome: A Randomized Controlled Crossover Trial.

SCOPE: Okara is a fiber-rich food by-product whereby biovalorization with Rhizopus oligosporus can improve its nutritional quality, generating fermentable substrates for improved gut health maintenance. This study evaluates the impact of okara- and biovalorized okara-containing biscuits consumption on gut health in Singapore adults. METHODS AND RESULTS: Participants consume control (C), 20% flour-substituted okara (AOK), and 20% flour-substituted biovalorized okara (RO) biscuits for three weeks, with assessment of gut metabolites, microbiome, and dietary intake. Fecal valeric acid is significantly higher with RO compared to AOK (p = 0.005). RO and AOK have significantly higher total serum short-chain fatty acids (p = 0.002 and 0.018 respectively) and acetic acid (p = 0.007 and 0.030 respectively) compared to C. Higher serum propionic acid (p = 0.004) and lower fecal lithocholic acid (p = 0.009) are observed with RO. Although serum zonulin shows no significant difference amongst interventions, AOK reduces Clostridiales while RO increases Bifidobacterium. CONCLUSION: Okara consumption improves serum SCFA regardless of fermentation while biovalorized okara further enhances gut metabolites by modulating gut microbiome.

Intestinal microecology associated with fluoride resistance capability of the silkworm (Bombyx mori L.).

The silkworm (Bombyx mori L.) is an ideal model of Lepidoptera. However, the diversity and function of the intestinal microbiota in the gut of silkworm remain largely unknown. Changes in the intestinal microecology in fluoride-resistant strain T6 and fluoride-susceptible strain 734 of the silkworm in response to fluoride exposure were investigated. T6 and 734 were treated with 200 mg/kg fluoride (designated as T6-T and 734-T groups) and deionized water (designated as T6-C and 734-C groups). Culture-dependent approach revealed that the numbers of intestinal bacteria in the 734-T group significantly decreased compared with that in the 734-C group (4.8 ± 0.6 × 10(7) CFU/mL vs. 7.5 ± 0.7 × 10(7) CFU/mL; P < 0.05). Analyses of the intestinal content pH showed that the pH decreased in the 734-T group only. Additionally, SCFA concentrations significantly decreased in both treatment groups compared with the control groups. High-throughput sequencing indicated that the intestinal microbiota in the 734-T group was significantly more diverse than those in the other groups. The bacterial community was composed of two dominant groups (Firmicutes and Proteobacteria). Principal component analyses revealed a significant difference in the composition of the intestinal microbiota in the 734-T group compared with those in the other groups. Thaumarchaeota and Euryarchaeota were more abundant in the 734-T group, but they were less abundant in the other groups. This study enhances our understanding about the diversity and function of silkworm intestinal microbiota in response to fluoride exposure among silkworm strains with diverse resistance.

Identification and Characterization of Bacillus cereus SW7-1 in Bombyx mori (Lepidoptera: Bombycidae).

The bacterial diseases of silkworms cause significant reductions in sericulture and result in huge economic loss. This study aimed to identify and characterize a pathogen from diseased silkworm. SW7-1, a pathogenic bacterial strain, was isolated from the diseased silkworm. The strain was identified on the basis of its bacteriological properties and 16S rRNA gene sequence. The colony was round, slightly convex, opaque, dry, and milky on a nutrient agar medium, the colony also exhibited jagged edges. SW7-1 was Gram-positive, without parasporal crystal, and 0.8-1.2 by 2.6-3.4 µm in length, resembling long rods with rounded ends. The strain was positive to most of the physiological biochemical tests used in this study. The strain could utilize glucose, sucrose, and maltose. The results of its 16S rRNA gene sequence analysis revealed that SW7-1 shared the highest sequence identity (>99%) with Bacillus cereus strain 14. The bacterial strain was highly susceptible to gentamycin, streptomycin, erythromycin, norfloxacin, and ofloxacin and moderately susceptible to tetracycline and rifampicin. It exhibited resistance to other antibiotics. SW7-1 had hemolytic activity and could produce extracellular casease, lipase, and amylase. SW7-1 could reproduce septicemia-like symptoms with high mortality rate when re-fed to healthy silkworm. .The median lethal concentration (LC50) was 5.45 × 10(4) cfu/ml. Thus, SW7-1 was identified as B. cereus, which is a pathogen for silkworm and human infections are possible.