Sixty neonatal Hu lambs were weaned at either 21 (n = 30) (early weaning, EW) or 49 days (n = 30) of age (control, CON). The starter intake and body weight (BW) of lambs was recorded weekly from birth to 63 days of age. Diarrhea rate of lambs was measured from birth to 35 days. Six randomly selected lambs from each treatment were slaughtered at 26, 35, and 63 days of age, respectively. Ruminal pH, NH₃-N, and volatile fatty acid (VFA) concentration, as well as serum parameters including immunity, antioxidant status, and inflammatory parameters from randomly selected lambs from each treatment were measured. There was no difference in BW at birth and day 21 between the two groups of lambs (p > 0.05). However, BW of the lambs in the EW group was significantly lower than those in the CON group (p < 0.01) from 28 to 49 days of age. Average daily gain (ADG) of the lambs in the EW group was significantly lower than those in the CON group (p < 0.01) at three weeks after early weaning. Starter intake of the lambs in the EW group was obviously higher than that in the CON group (p < 0.01) from day 28 to 49. In addition, the diarrhea rate was significantly higher than that in the CON group from day 5 to 14 after weaning (p < 0.01). The EW group had heavier carcasses (p < 0.01) and rumen relative to whole stomach weights (p < 0.01). Rumen pH was increased by age (p < 0.01) and was not affected by early weaning (p > 0.05). Early weaning decreased abomasum relative to whole stomach weight (p < 0.01) and increased total VFA concentrations (p < 0.01) at day 26. There was no difference in lambs’ immunity and stress indicators (p > 0.05). The results indicated that lambs weaned at 21 days of age had decreased ADG and higher diarrhea rate, although the overall immunity was not compromised. Long-term study is needed to further validate the feasibility of early weaning strategy in lambs.

A pullulanase gene (Pul3YH5) of 2568 bp, which encodes a protein containing 855 amino acid residues, was cloned from the alkaliphilic bacterium Exiguobacterium acetylicum YH5. The pullulanase (Pul3YH5) contains the YNWGYDP motif of type I pullulanase as well as four conserved glycoside hydrolase sequences of the GH13 (α‐amylase) family. When the pullulanase gene was cloned and expressed in Escherichia coli BL21 (DE3) plysS, the recombinant pullulanase had a molecular mass of ˜100·0 kDa. It was optimally active at 50°C and pH 6·0, alkali‐tolerant and displayed excellent stability (>93·0%) over a broad pH range (4·0‒10·0) when incubated for 30 min without substrate. The enzyme activity of Pul3YH5 was significantly enhanced in the presence of Co²⁺, Fe²⁺ and Mn²⁺ and was inhibited by Cu²⁺, SDS, β‐mercaptoethanol and EDTA. The enzyme displayed the highest specificity for pullulan (K_m = 0·12 ± 0·02 mg ml⁻¹), followed by soluble starch (K_m = 0·69 ± 0·04 mg ml⁻¹). Substrate hydrolysis demonstrated that pullulanase from E. acetylicum liberated maltotriose from pullulan, although hydrolytic activity was also detected with soluble starch, amylopectin, β‐limited dextrin and glycogen. These enzymatic properties indicate that Pul3YH5 is alkali‐tolerant pullulanase and that Pul3YH5 could be useful in the detergent industry. Significance and Impact of the Study Pullulanases have great potential in various industries, ranging from food (high fructose and glucose syrups) to washing detergent industries. In this study, the gene encoding the novel pullulanase from E. acetylicum YH5 was cloned and sequenced, then expressed in E. coli. The properties of the recombinant enzyme in E. coli were also determined. The pullulanase from E. acetylicum YH5 is alkaline tolerant and has a high optimum temperature, making it a candidate for applications in the detergent industry.

As an eco-friendly biocatalyst for alginate hydrolysis, bacteria-derived alginate lyase (AlgL) has been widely used in research and industries to produce oligosaccharides. However, the cost of AlgL enzyme production remains high due to the low expression and difficulty in purification from bacterial cells. In this study we report an effective method to overexpress the Pseudomonas aeruginosa AlgL (paAlgL) enzyme in Pichia pastoris. Fused with a secretory peptide, the recombinant paAlgL was expressed extracellularly and purified from the culture supernatant through a simple process. The purified recombinant enzyme is highly specific for alginate sodium with a maximal activity of 2,440 U/mg. The enzymatic activity remained stable below 45°C and at pH between 4 and 10. The recombinant paAlgL was inhibited by Zn²⁺, Cu²⁺, and Fe²⁺ and promoted by Co²⁺ and Ca²⁺. Interestingly, we also found that the recombinant paAlgL significantly enhanced the antimicrobial activity of antibiotics ampicillin and kanamycin against Pseudomonas aeruginosa. Our results introduce a method for efficient AlgL production, the characterization, and a new feature of the recombinant paAlgL as an enhancer of antibiotics against Pseudomonas aeruginosa.

Our objective was to evaluate the effects of dietary supplementation with glycerol monolaurate (GML) or the combination (Solider, SOL) of GML and tributyrin (TB) on the growth performance and rumen microbiome of weaned lambs. Thirty-six male Hu lambs (11.46 ± 0.88 kg BW and 40 ± 5 days of age) were divided into three treatment groups: (1) CON: basal diet, (2) GML: basal diet supplemented with GML at 1.84 g/kg DM, and (3) SOL: basal diet supplemented with SOL at 3 g/kg DM. GML increased the final BW (p = 0.04) and ADG (p = 0.02) compared with CON. There were no significant differences in the DMI (p > 0.10) among the three treatment groups. GML and SOL tended to decrease the dry matter intake/average daily gain (p = 0.07) compared with CON. GML tended to increase the apparent digestibility of CP (p = 0.08) compared with CON. SOL increased the apparent digestibility of NDF (p = 0.04) compared with CON. The Chao1 and Shannon indexes of SOL were both significantly higher than those of the other groups (p = 0.01). LefSE analysis showed that Bifidobacteriaceae of the Bifidobacteriales was enriched in the GML group. In addition, compared with GML, SOL reduced the relative abundance of Actinobacteria (p < 0.01) and increased the relative abundance of Verrucomicrobia (p = 0.05), and GML reduced the relative abundance of Ruminococcus (p = 0.03). Our results indicated that dietary supplementation with GML or SOL improved growth performance and feed conversion, and changed the rumen microbiome of weaned lambs.