Some lactobacilli have protective effects against some heavy metals in mammals, but the underlying mechanism is not fully understood. To evaluate the remediation potency and the mechanism of Lactobacillus against chromium (Cr) in mice, Lactobacillus plantarum TW1-1 was orally administrated to Kunming mice for 7 weeks during exposure to 1 mM K2Cr2O7 in drinking water. Results showed that TW1-1 helped to decrease Cr accumulation in tissues and increase Cr excretion in feces, and may also attenuate alterations in oxidative stress and histopathological changes caused by Cr exposure. Moreover, the chromate reduction ability of fecal bacteria doubled after administration of TW1-1 upon Cr induction. MiSeq sequencing of fecal bacterial 16S rRNA genes revealed that the overall structures of gut microbiota was shifted by Cr exposure and partially restored by TW1-1. The abundances of 49 of the 79 operational taxonomic units altered by Cr were reversed by TW1-1. Based on these, we proposed a working model of TW1-1 against Cr: TW1-1 helps to remove Cr from the host and meanwhile acts as a regulator of gut microbiota, which aids in chromate reduction and provide protection against Cr. We call this process of remediation of heavy metal in the gut “gut remediation”.

Gut remediation: a potential approach to reducing chromium accumulation using Lactobacillus plantarum TW1-1.

OBJECTIVE In order to detect the effect of lactic acid bacteria isolated from Tibetan Plateau on silage fermentation quality of Elms nutans METHODS We used 3 isolated lactic acid bacteria with better growth at low temperatures of 10 and 15 degrees C at ensiling of Elymus nutans Subsequently, effects of the selected lactic acid bacteria on fermentation profiles of Elymus nutans silages stored at 15 and 25 degrees C were evaluated by using the same species of commercial inoculants as the control RESULTS PP-6 isolated from Tibetan Plateau could ferment raffinose, lactose, sorbitol, melibiose and sucrose, and LS-5 could ferment cottonseed sugar, laetrile, rhamnose, lactose, sorbitol, xylose, arabinose, melibiose and sucrose, but the same species of commercial strains could not use these sugars Inoculation of these three strains into Elymus nutans at 15 and 25 degrees C ensiled for 50 d, we found that LS-5 significantly reduced silage pH, propionic acid concentration and ratio of ammonia nitrogen/total nitrogen at 15 degrees C (P < 005), salvaged more water-soluble carbohydrate and crude protein; Application of LP-2 and PP-6 as a combined inoculant to Elymus nutans significantly improved lactic acid concentration (P < 005), resulting in a lower ratio of ammonia nitrogen/total nitrogen, saved more crude protein and significantly reduced neutral detergent fiber content (P < 005) as compared with the commercial strains CONCLUSION The three isolated strains can improve silage quality of Elymus nutans growing on the Qinghai-Tibetan Plateau at low temperature, but these strains have no obvious advantages at 25 degrees C in comparison with the commercial inoculants

Xusheng Guo

Papers

Effect of lactic acid bacteria isolated from Tibetan Plateau on silage fermentation quality of Elms nutans