Fermentation by Lactobacillus can increase the nutritional value of feed, which is advantageous for pig production. However, the effects of Lactobacillus -driven feed fermentation on the emission of odors from pig feces are unclear. Here, we evaluated how feed fermentation by Lactobacillus affects the concentration of odor molecules in feces (CO ₂ , NH ₃ , H ₂ S, indole, and skatole) and analyzed the changes in fecal microbiota and metabolites during fecal storage. Pigs reared on fermented feed had a higher average daily gain (ADG) and lower feed-to-gain ( F / G ) ratio than the control group. By the 3rd and 5th days, the concentration of CO ₂ in feces from pigs in the fermentation group significantly decreased, and the contents of H ₂ S, NH ₃ , and skatole in the fermentation group were significantly lower than those in the control group on the 1st, 3rd, and 5th days of fecal storage. The fermentation group exhibited a higher Bacteroidetes abundance on the 3rd and 5th days. With prolonged fecal storage, the fermentation group exhibited a higher abundance of Weissella and Lactobacillus and a lower abundance of Streptococcus . The Lactobacillus fermentation group also showed lower levels of secondary amino acid metabolites, such as 6-hydroxyhexanoic acid and 5-aminopentanoic acid. The pure strain Weissella cibaria ZWC030, which could inhibit the production of skatole in vitro , was successfully isolated from the fermentation group. Overall, the study revealed the interrelationships among fecal microbiota, metabolites, and odor molecules. The findings provide a new avenue for the application of Lactobacillus -driven feed fermentation to promote ADG, decrease the F / G ratio in pigs during growth, and reduce environmental pollution. IMPORTANCE: Our present study showed that dietary supplementation with feed fermented by Lactobacillus could promote the growth performance of pigs, regulate the microbiota, and inhibit the growth of harmful bacteria. It could prevent the accumulation of toxic substances and reduce odor emission from pig feces, thereby reducing environmental pollution. In addition, one key triumph of the present study was the isolation of Weissella cibaria ZWC030, and the strain could inhibit the production of skatole in vitro in our present results.

Xylanase degrades xylan into monomers of various sizes by catalyzing the endohydrolysis of the 1,4-β-D-xylosidic linkage randomly, possessing potential in wide industrial applications. Most of xylanases are susceptible to be inactive when suffering high temperature and high alkaline process. Therefore, it is necessary to develop a high amount of effective thermoalkaliphilic xylanases. This study aims to enhance thermoalkaliphilic xylanase production in Pichia pastoris through fermentation parameters optimization and novel efficient fed-batch strategy in high cell-density fermentation. Recombinant xylanase activity increased 12.2%, 7.4%, 12.0% and 9.9% by supplementing the Pichia pastoris culture with 20 g/L wheat bran, 5 mg/L L-histidine, 10 mg/L L-tryptophan and 10 mg/L L-methionine in shake flasks, respectively. Investigation of nutritional fermentation parameters, non-nutritional fermentation parameters and feeding strategies in 1 L bioreactor and 1 L shake flask revealed that glycerol and methanol feeding strategies were the critical factors for high cell density and xylanase activity. In 50 L bioreactor, a novel glycerol feeding strategy and a four-stage methanol feeding strategy with a stepwise increase in feeding rate were developed to enhance recombinant xylanase production. In the initial 72 h of methanol induction, the linear dependence of xylanase activity on methanol intake was observed (R2 = 0.9726). The maximum xylanase activity was predicted to be 591.2 U/mL, while the actual maximum xylanase activity was 560.7 U/mL, which was 7.05 times of that in shake flask. Recombinant xylanase retained 82.5% of its initial activity after pre-incubation at 80 °C for 50 min (pH 8.0), and it exhibited excellent stability in the broad temperature (60–80 °C) and pH (pH 8.0–11.0) ranges. Efficient glycerol and methanol fed-batch strategies resulting in desired cell density and xylanase activity should be applied in other P. pastoris fermentation for other recombinant proteins production. Recombinant xylanases with high pH- and thermal-stability showed potential in various industrial applications.

This study investigated the effects of Lactobacillus-fermented low-protein diet on the growth performance, nitrogen balance, fecal microbiota, and metabolomic profiles of finishing pigs. A total of 90 finishing pigs were assigned to one of three dietary treatments including a normal protein diet (CON) as well as two experimental diets in which a low-protein diet supplemented with 0 (LP) or 1% Lactobacillus-fermented low-protein feed (FLP). In comparison with CON, the LP and FLP significantly increased average daily gain (P = 0.044), significantly decreased feed to gain ratio (P = 0.021), fecal nitrogen (P < 0.01), urine nitrogen (P < 0.01), and total nitrogen (P < 0.01), respectively. The LP group exhibited increased abundances of unclassified_f_Selenomonadaceae, Coprococcus, Faecalibacterium, and Butyricicoccus, while the abundances of Verrucomicrobiae, Verrucomicrobiales, Akkermansiaceae, and Akkermansia were enriched in the FLP group. Low-protein diet-induced metabolic changes were enriched in sesquiterpenoid and triterpenoid biosynthesis and Lactobacillus-fermented low-protein feed-induced metabolic changes were enriched in phenylpropanoid biosynthesis and arginine biosynthesis. Overall, low-protein diet and Lactobacillus-fermented low-protein diet improved the growth performance and reduce nitrogen excretion, possibly via altering the fecal microbiota and metabolites in the finishing pigs. The present study provides novel ideas regarding the application of the low-protein diet and Lactobacillus-fermented low-protein diet in swine production.

We aimed to explore the effects of two different doses of Zn on the fecal microbiota in pigeons and the correlation between these effects and intestinal immune status. Zn doses affected pigeon growth performance, and pigeons in the T60 (60 mg/kg Zn) and T90 (90 mg/kg Zn) groups exhibited higher villus height and crypt depth in duodenum and ileum compared to the control group, respectively. Supplementation with Zn increased the expression of the IL8, CD798, TJP and NKTR genes (p < 0.05), while enhancing serum immunoglobulin (Ig) G, IgM, and IgA concentrations compared to the control pigeons (p < 0.05). T60 treatment reduced relative Actinobacteriota abundance, while Lactobacillus spp. abundance was highest in the T90 group compared to the two other groups. The core functional genera significantly associated with immune indices in these pigeons were Rhodococcus erythropolis and Lactobacillus ponti. Our findings will help facilitate the application of dietary Zn intake in pig production.