Non-contact detection method of pregnant sows backfat thickness based on two-dimensional images.

Since sow backfat thickness (BFT) is highly correlated with its service life and reproductive effectiveness, dynamic monitoring of BFT is a critical component of large-scale sow farm productivity. Existing contact measures of sow BFT have their problems including, high measurement intensity and sows' stress reaction, low biological safety, and difficulty in meeting the requirements for multiple measurements. This article presents a two-dimensional (2D) image-based approach for determining the BFT of pregnant sows when combined with the backfat growth rate (BGR). The 2D image features of sows extracted by convolutional neural networks (CNN) and the artificially defined phenotypic features of sows such as hip width, hip height, body length, hip height-width ratio, length-width ratio, and waist-hip ratio, were used respectively, combined with BGR, to construct a prediction model for sow BFT using support vector regression (SVR). Following testing and comparison, it was shown that using CNN to extract features from images could effectively replace artificially defined features, BGR contributed to the model's accuracy improvement. The CNN-BGR-SVR model performed the best, with R2 of 0.72 and mean absolute error of 1.21 mm, and root mean square error of 1.50 mm, and mean absolute percentage error of 7.57%. The results demonstrated that the CNN-BGR-SVR model based on 2D images was capable of detecting sow BFT, establishing a new reference for non-contact sow BFT detection technology.

Physiological and metabolic analysis of nitrate reduction on poly-gamma-glutamic acid synthesis in Bacillus licheniformis WX-02.

Nitrate is an important nitrogen source for organism, but whether and how nitrate improves poly-γ-glutamic acid (γ-PGA) production of bacterial is not clear. The effect of nitrate on γ-PGA production of Bacillus licheniformis WX-02 was investigated. By addition of 50 mmol/L nitrate, the γ-PGA yield reached 12.3 ± 0.21 g/L, which increased 2.3-fold compared to the control. The mechanism of enhanced γ-PGA production was further investigated by analysis of nitrate reduction, physiology, pyruvate overflow metabolism and energy synthesis. Nitrate reduction was only carried out in the middle stage of γ-PGA fermentation. The result of consumption of nutrients showed that glucose uptake was not effected and the L-glutamic acid utilization efficiency increased from 48.3 to 77.0 %. The date of overflow metabolism obtained from high-performance liquid chromatography showed that the metabolism of pyruvate, formate, lactate and acetoin was both heightened by nitrate reduction, while the 2,3-butanediol biosynthesis was decreased. Meanwhile, the change of energy indicated that more ATP was synthesized during nitrate reduction. In summary, nitrate was a positive effector of γ-PGA biosynthesis in B. licheniformis WX-02 and nitrate reduction affected multi-metabolism pathways, including glycolysis, overflow metabolism and energy metabolism.

Deletion of meso-2,3-butanediol dehydrogenase gene budC for enhanced D-2,3-butanediol production in Bacillus licheniformis.

BACKGROUND: D-2,3-butanediol has many industrial applications such as chiral reagents, solvents, anti-freeze agents, and low freezing point fuels. Traditional D-2,3-butanediol producing microorganisms, such as Klebsiella pneumonia and K. xoytoca, are pathogenic and not capable of producing D-2,3-butanediol at high optical purity. Bacillus licheniformis is a potential 2,3-butanediol producer but the wild type strain (WX-02) produces a mix of D- and meso-type isomers. BudC in B. licheniformis is annotated as 2,3-butanediol dehydrogenase or acetoin reductase, but no pervious experiment was performed to verify this hypothesis. RESULTS: We developed a genetically modified strain of B. licheniformis (WX-02 ΔbudC) as a D-2,3-butanediol producer with high optimal purity. A marker-less gene deletion protocol based on a temperature sensitive knock-out plasmid T2-Ori was used to knock out the budC gene in B. licheniformis WX-02. The budC knock-out strain successfully abolished meso-2,3-butanediol production with enhanced D-2,3-butanediol production. No meso-BDH activity was detectable in cells of this strain. On the other hand, the complementary strain restored the characteristics of wild strain, and produced meso-2,3-butanediol and possessed meso-BDH activity. All of these data suggested that budC encoded the major meso-BDH catalyzing the reversible reaction from acetoin to meso-2,3-butanediol in B. licheniformis. The budC knock-out strain produced D-2,3-butanediol isomer only with a high yield of 30.76 g/L and a productivity of 1.28 g/L-h. CONCLUSIONS: We confirmed the hypothesis that budC gene is responsible to reversibly transfer acetoin to meso-2,3-butanediol in B. licheniformis. A mutant strain of B. licheniformis with depleted budC gene was successfully developed and produced high level of the D-2,3-butanediol with high optimal purity.