Residue Elimination Patterns and Determination of the Withdrawal Times of Seven Antibiotics in Eggs of Taihang Chickens.

The objective of this study was to examine the residue elimination patterns of seven antibiotics in the eggs of Taihang chickens under free-range conditions and develop suitable withdrawal times (WDTs). A total of 240 healthy Taihang chickens, aged 180 days, were randomly divided into eight groups of 30 birds each. The first seven groups were administered oxytetracycline, chlortetracycline, erythromycin, tylosin, tylvalosin, lincomycin, and tiamulin, respectively, in accordance with the maximum dosages and longest durations of treatment recommended by the Veterinary Pharmacopoeia of the People's Republic of China.

A Rapid Detection Method for H3 Avian Influenza Viruses Based on RT-RAA.

The continued evolution of H3 subtype avian influenza virus (AIV)-which crosses the interspecific barrier to infect humans-and the potential risk of genetic recombination with other subtypes pose serious threats to the poultry industry and human health. Therefore, rapid and accurate detection of H3 virus is highly important for preventing its spread. In this study, a method based on real-time reverse transcription recombinase-aided isothermal amplification (RT-RAA) was successfully developed for the rapid detection of H3 AIV.

Identification and characterization of a moonlighting protein-enolase for surface display in Streptococcus thermophilus.

Background: Streptococcus thermophilus is an important food starter and receiving more attention to serve as cell factories for production of high-valued metabolites. However, the low yields of intracellular or extracellular expression of biotechnological and biomedical proteins limit its practical applications.

Results: Here, an enolase EnoM was identified from S.

Targeted and Repetitive Chromosomal Integration Enables High-Level Heterologous Gene Expression in .

is a potential cell factory for the production of enzymes and bioactive molecules using episomal plasmids, which suffer from genetic instability. While chromosomal integration strategies can provide genetic stability of recombinant proteins, low expression yields limit their application. To address this problem, we developed a two-step integration strategy in by combination of the LCABL_13040-50-60 recombineering system (comprised of LCABL_1340, LCABL_13050, and LCABL_13060) with the Cre/ site-specific recombination system, with an efficiency of ∼3.

A Single-Plasmid Genome Editing System for Metabolic Engineering of .

Genome engineering of , an important industrial microorganism for dairy fermented product, currently relies on inefficient and time-consuming double crossover events. In this study, we developed an easy-to-use genome engineering strategy for metabolic engineering of for acetoin production. Plasmid pMSP456-Cre, that contains prophage recombinase operon driven by the nisin-controlled inducible expression (NICE) system and the site-specific recombinase gene under the control of the promoter of the lactose operon from , was constructed.

Coupling the recombineering to Cre-lox system enables simplified large-scale genome deletion in Lactobacillus casei.

Background: Lactobacillus casei is widely used in the dairy and pharmaceutical industries and a promising candidate for use as cell factories. Recently, genome sequencing and functional genomics provide the possibility for reducing L. casei genome.

Paenibacillus panacisoli enhances growth of Lactobacillus spp. by producing xylooligosaccharides in corn stover ensilages.

The knowledge about the association of lignocellulosic biomass-degrading microbes with lactic acid bacteria (LAB) in ensilages is still limited. Paenibacillus strains are important microbes in sustainable agriculture. Here, P.

Identification and functional analysis of potential prophage-derived recombinases for genome editing in Lactobacillus casei.

Numerous lactic acid bacteria (LAB) bacteriophage genomes have been sequenced, while the functional genes are yet to be exploited. In this study, a λ Red-like recombinase operon LCABL_13040-50-60 was identified from a prophage PLE3 in Lactobacillus casei BL23 genome, and its recombination function was confirmed by the replacement of a 167-bp galK fragment with chloramphenicol-resistant gene (cat) in the L. casei BL23 genome.

Development of a counterselectable seamless mutagenesis system in lactic acid bacteria.

Background: Lactic acid bacteria (LAB) are receiving more attention to act as cell factories for the production of high-value metabolites. However, the molecular tools for genetic modifying these strains are mainly vector-based double-crossover strategies, which are laborious and inefficient. To address this problem, several counterselectable markers have been developed, while few of them could be used in the wild-type host cells without pretreatment.