Spatial-Potential-Color-Resolved Bipolar Electrode Electrochemiluminescence Biosensor Using a CuMoOx Electrocatalyst for the Simultaneous Detection and Imaging of Tetracycline and Lincomycin.

A spatial-potential-color-resolved bipolar electrode electrochemiluminescence biosensor (BPE-ECL) using a CuMoOx electrocatalyst was constructed for the simultaneous detection and imaging of tetracycline (TET) and lincomycin (LIN). HOF-101 emitted peacock blue light under positive potential scanning, and CdSe quantum dots (QDs) emitted green light under negative potential scanning. CuMoOx could catalyze the electrochemical reduction of H2O2 to greatly increase the Faradic current of BPE and realize the ECL signal amplification. In channel 1, CuMoOx-Aptamer II (TET) probes were introduced into the BPE hole (left groove A) by the dual aptamer sandwich method of TET. During positive potential scanning, the polarity of BPE (left groove A) was negative, resulting in the electrochemical reduction of H2O2 catalyzed by CuMoOx, and the ECL signal of HOF-101 was enhanced for detecting TET. In channel 2, CuMoOx-Aptamer (LIN) probes were adsorbed on the MXene of the driving electrode (DVE) hole (left groove B) by hydrogen-bonding and metal-chelating interactions. LIN bound with its aptamers, causing CuMoOx to fall off. During negative potential scanning, the polarity of DVE (left groove B) was negative and the Faradic current decreased. The ECL signal of CdSe QDs was reduced for detecting LIN. Furthermore, a portable mobile phone imaging platform was built for the colorimetric (CL) detection of TET and LIN. Thus, the multiple mode-resolved detection of TET and LIN could be realized simultaneously with only one potential scan, which greatly improved detection accuracy and efficiency. This study opened a new technology of BPE-ECL sensor application and is expected to shine in microchips and point-of-care testing (POCT).

Adsorption of sulfamethoxazole and lincomycin from single and binary aqueous systems using acid-modified biochar from activated sludge biomass.

The extensive use of pharmaceuticals has raised growing concerns regarding their presence in surface waters. High concentrations of sulfamethoxazole (SMX) and lincomycin (LIN), as commonly prescribed antibiotics, persist in various wastewaters and surface waters, posing risks to public health and the environment. Biochar derived from accessible biowaste, like activated sludge biomass, offers a sustainable and eco-friendly solution to mitigate antibiotic release into water systems. This study investigates the effectiveness of H3PO4-modified activated sludge-based biochar (PBC) synthesized through microwave (MW) heating for the adsorption of SMX and LIN antibiotics. The synthesis parameters of PBC were optimized using a central composite design considering MW power, time, and H3PO4 concentration. Characterization results validate the efficacy of the synthesis process creating a specific surface area of 365 m2/g, and well-developed porosity with abundant oxygen-containing functional groups. Batch and dynamic adsorption experiments were piloted to assess the adsorption performance of PBC in single and binary antibiotic systems. Results show that PBC exhibits a higher affinity for SMX rather than LIN, with maximum adsorption capacities of 45.6 mg/g and 26.6 mg/g, respectively. Based on kinetic studies chemisorption is suggested as the primary mechanism for SMX and LIN removal. Equilibrium studies show a strong agreement with the Redlich-Peterson isotherm, suggesting a composite adsorption mechanism with a greater probability of multilayer adsorption for both antibiotics. Hydrogen bonding and π-π electron sharing are suggested as the prevailing adsorption mechanisms of SMX and LIN on the modified biochar. Furthermore, a dynamic adsorption system was replicated using a fixed bed column setup, demonstrating effective removal of SMX and LIN from pure water and real wastewater samples using PBC-loaded hydrogel beads (PBC-B). These findings serve as crucial support for upcoming studies concerning the realistic application of sludge-based biochar in the removal of antibiotics from water systems.

An electrochemiluminescence sensor based on Ag NPs amplifying PDDA-modified TbPO4:Ce NWs signal for sensitive detection of lincomycin.

The residue of lincomycin in water will not only aggravate the drug resistance of bacteria but also cause damage to the human body through biological accumulation. In this work, an electrochemiluminescence (ECL) aptasensor for the detection of lincomycin was constructed based on polydimethyldiallylammonium chloride (PDDA) functionalized Ce-doped TbPO4 nanowires (PDDA-TbPO4:Ce NWs) and silver nanoparticles (Ag NPs). TbPO4:Ce NWs were used as the luminophore, and PDDA was used to functionalize the luminophore to make the surface of the luminophore positively charged. The negatively charged silver nanoparticles were combined with PDDA-TbPO4:Ce NWs by electrostatic interaction. Ag NPs accelerated the electron transfer rate and promoted the ECL efficiency, which finally increased the ECL intensity of TbPO4:Ce NWs by about 4 times. Under the optimal conditions, the detection limit of the ECL sensor was as low as 4.37 × 10-16 M, and the linear range was 1 × 10 - 15 M to 1 × 10 - 5 M, with good selectivity, stability, and repeatability. The sensor can be applied to the detection of lincomycin in water, and the recovery rate is 97.7-103.4 %, which has broad application prospects.

[Characteristics and Risk Assessment of Antibiotic Contamination in Oujiang River Basin in Southern Zhejiang Province].

Antibiotic pollution in the environment has a negative impact on ecosystem security. Taking the Oujiang River Basin as an example,high-performance liquid chromatography mass spectrometry(LC-MS)was used to detect the concentration of six classes of 35 antibiotics in the surface water of the southern Zhejiang River Basin. The concentration level and spatial distribution of antibiotics were analyzed,the risk of antibiotics to ecology and human health were assessed using relevant models,and the sources of antibiotics were discussed. The results showed that in 20 sampling sites,a total of four classes of 12 antibiotics were detected,including sulfonamides,quinolones,tetracyclines,and lincosamides. The total concentration was ND-1 018 ng·L-1. The highest detection rate was that of Lincomycin(90.48%),followed by that of sulfapyridine(38.10%). The three antibiotics with the highest average concentrations were ofloxacin(12.49 ng·L-1),Lincomycin(11.08 ng·L-1),and difloxacin(7.38 ng·L-1). Antibiotics in the basin showed mainly spotty pollution,which had large spatial differentiation. The average concentration of antibiotics in the upstream(54.39 ng·L-1)was higher than that mid-downstream(46.64 ng·L-1). The degree of antibiotic pollution from upstream to downstream showed a characteristic of being "sparse in the upstream and dense in the downstream. " This indicated that the concentration of antibiotics in the upstream was significantly different,whereas the pollution degree of antibiotics in the downstream was uniform. The upstream was mainly polluted by health,livestock,and poultry breeding wastewater emissions,and downstream pollution was mainly caused by densely populated activities and the rapid development of economy,trade,and industry. The ecological risk assessment results showed that the upstream site H6 had the highest risk quotient,ofloxacin and enrofloxacin had high risk levels, and lincomycin had a moderate risk level. Health risk assessment results showed that the Oujiang River surface water antibiotics posed no risk to human health.

Supersensitive detection of lincomycin with an ECL aptasensor based on the synergistic integration of gold-functionalized upconversion nanoparticles and thiolated 3,4,9,10-perylene tetracarboxylic acid.

In this work, the supersensitive and selective determination of lincomycin (Lin) was achieved using a novel electroluminescent (ECL) aptasensor based on the synergistic integration of gold functionalized upconversion nanoparticles (UCNPs) and thiolated 3,4,9,10-perylene tetracarboxylic acid (PTCA). The integration of two luminophores of UCNPs and PTCA combined the merits of the cathodoluminescence stability of UCNPs and the high quantum yield of PTCA, which significantly promoted the ECL signal and analytical performance of the proposed sensor. The introduction of gold nanoparticles in UCNPs can not only improve the conductivity and ECL performance of UCNPs but also cause them to easily integrate with thiolated PTCA (t-PTCA) via an Au-S bond. The ECL signal of UCNPs@Au/t-PTCA/GCE was almost twice as strong as that of t-PTCA/GCE and tenfold higher than that of UCNPs@Au/GCE. Because of the non-conductive protein of the Lin aptamer, the ECL intensity of apt/UCNPs@Au/t-PTCA/GCE noticeably decreased. In the presence of Lin, the aptamer was pulled down from the sensing interface, resulting in the recovery of the ECL intensity of the sensor. Under optimal conditions, our proposed sensor can quantify the concentration of Lin in the range from 1.0 × 10-15 to 1.0 × 10-7 M with a low detection limit of 2.4 × 10-16 M (S/N = 3), exhibiting high sensitivity and specificity for the determination of Lin.

Degradation kinetics of veterinary antibiotics and estrogenic hormones in a claypan soil.

Veterinary antibiotics and estrogens are excreted in livestock waste before being applied to agricultural lands as fertilizer, resulting in contamination of soil and adjacent waterways. The objectives of this study were to 1) investigate the degradation kinetics of the VAs sulfamethazine and lincomycin and the estrogens estrone and 17ß-estradiol in soil mesocosms, and 2) assess the effect of the phytochemical DIBOA-Glu, secreted in eastern gamagrass (Tripsacum dactyloides) roots, on antibiotic degradation due to the ability of DIBOA-Glu to facilitate hydrolysis of atrazine in solution assays. Mesocosm soil was a silt loam representing a typical claypan soil in portions of Missouri and the Central United States. Mesocosms (n = 133) were treated with a single target compound (antibiotic concentrations at 125 ng g-1 dw, estrogen concentrations at 1250 ng g-1 dw); a subset of mesocosms treated with antibiotics were also treated with DIBOA-Glu (12,500 ng g-1 dw); all mesocosms were kept at 60% water-filled pore space and incubated at 25 °C in darkness. Randomly chosen mesocosms were destructively sampled in triplicate for up to 96 days. All targeted compounds followed pseudo first-order degradation kinetics in soil. The soil half-life (t0.5) of sulfamethazine ranged between 17.8 and 30.1 d and ranged between 9.37 and 9.90 d for lincomycin. The antibiotics results showed no significant differences in degradation kinetics between treatments with or without DIBOA-Glu. For estrogens, degradation rates of estrone (t0.5 = 4.71-6.08 d) and 17ß-estradiol (t0.5 = 5.59-6.03 d) were very similar; however, results showed that estrone was present as a metabolite in the 17ß-estradiol treated mesocosms and vice-versa within 24 h. The antibiotics results suggest that sulfamethazine has a greater potential to persist in soil than lincomycin. The interconversion of 17ß-estradiol and estrone in soil increased their overall persistence and sustained soil estrogenicity. This study demonstrates the persistence of these compounds in a typical claypan soil representing portions of the Central United States.

Lincosamide Antibiotics: Structure, Activity, and Biosynthesis.

Lincosamides are naturally occurring antibiotics isolated from Streptomyces sp. Currently, lincomycin A and its semisynthetic analogue clindamycin are used as clinical drugs. Due to their unique structures and remarkable biological activities, derivatizations of lincosamides via semi-synthesis and biosynthetic studies have been reported. This review summarizes the structures and biological activities of lincosamides, and the recent studies of lincosamide biosynthetic enzymes.

Three new LmbU targets outside lmb cluster inhibit lincomycin biosynthesis in Streptomyces lincolnensis.

BACKGROUND: Antibiotics biosynthesis is usually regulated by the cluster-situated regulatory gene(s) (CSRG(s)), which directly regulate the genes within the corresponding biosynthetic gene cluster (BGC). Previously, we have demonstrated that LmbU functions as a cluster-situated regulator (CSR) of lincomycin. And it has been found that LmbU regulates twenty non-lmb genes through comparative transcriptomic analysis. However, the regulatory mode of CSRs' targets outside the BGC remains unknown. RESULTS: We screened the targets of LmbU in the whole genome of Streptomyces lincolnensis and found fourteen candidate targets, among which, eight targets can bind to LmbU by electrophoretic mobility shift assays (EMSA). Reporter assays in vivo revealed that LmbU repressed the transcription of SLINC_0469 and SLINC_1037 while activating the transcription of SLINC_8097. In addition, disruptions of SLINC_0469, SLINC_1037, and SLINC_8097 promoted the production of lincomycin, and qRT-PCR showed that SLINC_0469, SLINC_1037, and SLINC_8097 inhibited transcription of the lmb genes, indicating that all the three regulators can negatively regulate lincomycin biosynthesis. CONCLUSIONS: LmbU can directly regulate genes outside the lmb cluster, and these genes can affect both lincomycin biosynthesis and the transcription of lmb genes. Our results first erected the cascade regulatory circuit of LmbU and regulators outside lmb cluster, which provides the theoretical basis for the functional research of LmbU family proteins.

In vitro susceptibility of Brachyspira hyodysenteriae strains isolated in pigs in northern Italy between 2005 and 2022.

Pleuromutilins (tiamulin and valnemulin) are often used to treat swine dysentery due to recurrent resistance to macrolides and lincosamides. Recently, reduced susceptibility of B. hyodysenteriae to pleuromutilin has been reported. 536 strains of B. hyodysenteriae were isolated from symptomatic pigs weighing 30-150 kg in northern Italy between 2005 and 2022. B. hyodysenteriae was isolated by standard methods and confirmed by PCR. The minimum inhibitory concentration (MIC) to doxycycline, lincomycin, tiamulin, tylosin, tylvalosine and valnemulin was evaluated according to CLSI procedures and MIC data were reported as MIC 50 and MIC 90. The temporal trend of the MIC values was evaluated by dividing the data into two groups (2005-2013 and 2014-2022). Comparison of the distribution in frequency classes in the two periods was performed using Pearson's chi-squared test (p < 0.01). MIC 50 was close to the highest values tested for lincomycin and tylosin, while MIC 90 was close to the highest values tested for all antibiotics. 71.7% of the strains were susceptible to tylvalosin, while 75%-80.4% had reduced susceptibility to valnemulin and tiamulin, respectively. The difference in the distribution of MIC classes was statistically significant in the two periods for doxycycline, tiamulin, tylvalosin and valnemulin, and more MIC classes above the epidemiological cut-off were observed in 2014-2022 compared with 2005-2013. The evaluation of the trends during the period considered shows a decreasing rate of wild-type strains with MIC values below the epidemiological cut-off over time and confirms the presence of resistant strains in northern Italy.

Underlying the inhibition mechanisms of sulfate and lincomycin on long-term anaerobic digestion: Microbial response and antibiotic resistance genes distribution.

This study evaluated the resilience of a long-term anaerobic treatment system exposed to sulfate, lincomycin (LCM) and their combined stress. LCM was found to impede anaerobic propionate degradation, while sulfate for restraining methanogenic acetate utilization. The combined stress, with influent LCM of 200 mg/L and sulfate of 1404 mg/L, revealed severer inhibition on anaerobic digestion than individual inhibition, leading to 73.9 % and 38.5 % decrease in methane production and sulfate removal, respectively. Suppression on propionate-oxidizing bacteria like unclassified_f__Anaerolineae and unclassified_f__Syntrophaceae further demonstrated LCM's inhibitory effect on propionate degradation. Besides, the down-regulation of genes encoding dissimilatory sulfate reduction enzymes caused by LCM triggered great inhibition on sulfate reduction. A notable increase in ARGs was detected under sulfate-stressed condition, owing to its obvious enrichment of tetracycline-resistant genes. Genera including unclassified_f__Syntrophaceae, unclassified_f__Geobacteraceae and unclassified_f__Anaerolineaceae were identified as dominant host of ARGs and enriched by sulfate addition. Overall, these results could provide the theoretical basis for further enhancement on anaerobic digestion of pharmaceutical wastewater containing sulfate and lincomycin.

New targets of TetR-type regulator SLCG_2919 for controlling lincomycin biosynthesis in Streptomyces lincolnensis.

The transcription factor (TF)-mediated regulatory network controlling lincomycin production in Streptomyces lincolnensis is yet to be fully elucidated despite several types of associated TFs having been reported. SLCG_2919, a tetracycline repressor (TetR)-type regulator, was the first TF to be characterized outside the lincomycin biosynthetic cluster to directly suppress the lincomycin biosynthesis in S. lincolnensis. In this study, improved genomic systematic evolution of ligands by exponential enrichment (gSELEX), an in vitro technique, was adopted to capture additional SLCG_2919-targeted sequences harboring the promoter regions of SLCG_6675, SLCG_4123-4124, SLCG_6579, and SLCG_0139-0140. The four DNA fragments were confirmed by electrophoretic mobility shift assays (EMSAs). Reverse-transcription quantitative polymerase chain reaction (RT-qPCR) showed that the corresponding target genes SLCG_6675 (anthranilate synthase), SLCG_0139 (LysR family transcriptional regulator), SLCG_0140 (beta-lactamase), SLCG_6579 (cytochrome P450), SLCG_4123 (bifunctional DNA primase/polymerase), and SLCG_4124 (magnesium or magnesium-dependent protein phosphatase) in ΔSLCGL_2919 were differentially increased by 3.3-, 4.2-, 3.2-, 2.5-, 4.6-, and 2.2-fold relative to those in the parental strain S. lincolnensis LCGL. Furthermore, the individual inactivation of these target genes in LCGL reduced the lincomycin yield to varying degrees. This investigation expands on the known DNA targets of SLCG_2919 to control lincomycin production and lays the foundation for improving industrial lincomycin yields via genetic engineering of this regulatory network.

Oral bioavailability and egg drug residue of lincomycin in laying hens after different treatment.

Lincomycin (LCM) is an antibiotic used to treat severe bacterial infections in livestock and companion animals. In this study, we aimed to investigate the oral bioavailability of LCM with PK data after IV and PO administration and to compare differences in drug residue patterns in eggs. To ensure food safety, an additional study on egg residue was conducted using 3 different commercial LCM drugs. For bioavailability study, laying hens were divided into oral and intravenous (n = 8/group) groups and received single dose (10 mg/kg) of LCM. The limits of quantification for LCM were 0.729 µg/mL and 0.009 mg/kg in plasma and eggs, respectively. The oral group exhibited a significantly lower average serum drug concentration than the IV group, with a bioavailability of 2.6%. Furthermore, the egg residue profiles confirmed reduced systemic drug exposure after oral administration. For the commercial LCM drug egg residue experiment, laying hens were divided into low- and high-dose groups (n = 12/group) for each drug and treated with the recommended dosage and administration method for each respective drug. The eggs were collected and analyzed until 14 d after the last drug treatment. Despite differences in the LCM content and formulation among commercial drugs, all the tested commercial drugs showed average concentrations below the MRL in eggs within approximately 3 d after the last drug treatment. In this study, we have confirmed that LCM has a low oral absorption rate in laying hens, and this was consistent with the findings from the egg residue profiles. Further studies are requested to elucidate the exact reasons for evidently low oral drug absorption in laying hens.

An electrochemiluminescence aptasensor based on Ti3C2 QDs-1T/2H MoS2 nano-hybrid material for the highly sensitive detection of lincomycin.

Developing a highly selective and sensitive analysis strategy for lincomycin (LIN) is of great significance for environmental protection and food safety. Herein, we reported a novel electrochemiluminescence (ECL) aptasensor based on Ti3C2 QDs-1T/2H MoS2 nano-hybrid luminophore for detection of LIN. The hybridization of Ti3C2 QDs and 1T/2H MoS2 endowed nanocomposite with structural and compositional advantages for boosting the ECL performance of QDs by about three times. This enhancement could be attributed to the remarkable electrocatalytic activity and high conductivity exhibited by 1T/2H MoS2. Secondly, the great surface area of 1T/2H MoS2 is conducive to the high dispersion of Ti3C2 QDs, and its good conductivity could promote charge transfer. On the other hand, the excellent catalytic performance of 1T/2H MoS2 could facilitate the reduction of S2O82- to produce more radical, which significantly enhance the ECL signal of Ti3C2 QDs. Given these features, a sensor for detection of LIN was established based on specific recognition between target and aptamer. The sensor showed a good linear relationship (0.05 ng mL-1 ∼100 µg mL-1) with a detection limit as low as 0.02 ng mL-1. It is worth noting that this work has been validated in testing milk samples, exhibiting great potential application prospects in food analysis.

Biochar induces different responses of intracellular and extracellular antibiotic resistance genes and suppresses horizontal transfer during lincomycin fermentation dregs composting.

This study aims to indicate the influence of biochar on extracellular and intracellular ARGs (e/iARGs) variation and proliferation during lincomycin fermentation dregs (LFDs) compost. Biochar addition made iARGs keep reducing but eARGs increase to the maximum at the middle thermophilic phase and reduce at the end of the compost. Compared to control 3.15-log and 5.42-log reduction of iARGs and eARGs were observed, respectively. Biochar addition, bacterial community, and MGEs were the major contributors to iARGs and eARGs removal, with the contribution percentages of 38.4%, 31.0%, 23.7%, and 27.2%, 29.1%, and 34.9%, respectively. Moreover, biochar significantly inhibited eARGs transformation and RP4 plasmid conjugative transfer among E. coli DH5α and Pseudomonas aeruginosa HLS-6. The underlying mechanism involved in broken cell membranes of bacteria, and altered expression of oxidative stress genes and save our souls (SOS) response-related genes. The results indicated that biochar addition in composting could limit the dissemination of ARGs.

PAS domain containing regulator SLCG_7083 involved in morphological development and glucose utilization in Streptomyces lincolnensis.

BACKGROUND: Streptomyces lincolnensis is well known for producing the clinically important antimicrobial agent lincomycin. The synthetic and regulatory mechanisms on lincomycin biosynthesis have been deeply explored in recent years. However, the regulation involved in primary metabolism have not been fully addressed. RESULTS: SLCG_7083 protein contains a Per-Arnt-Sim (PAS) domain at the N-terminus, whose homologous proteins are highly distributed in Streptomyces. The inactivation of the SLCG_7083 gene indicated that SLCG_7083 promotes glucose utilization, slows mycelial growth and affects sporulation in S. lincolnensis. Comparative transcriptomic analysis further revealed that SLCG_7083 represses eight genes involved in sporulation, cell division and lipid metabolism, and activates two genes involved in carbon metabolism. CONCLUSIONS: SLCG_7083 is a PAS domain-containing regulator on morphological development and glucose utilization in S. lincolnensis. Our results first revealed the regulatory function of SLCG_7083, and shed new light on the transcriptional effects of SLCG_7083-like family proteins in Streptomyces.

Synergistic approach for acne vulgaris treatment using glycerosomes loaded with lincomycin and lauric acid: Formulation, in silico, in vitro, LC-MS/MS skin deposition assay and in vivo evaluation.

This study aims to develop a pharmaceutical formulation that combines the potent antibacterial effect of lincomycin and lauric acid against Cutibacterium acnes (C. acnes), a bacterium implicated in acne. The selection of lauric acid was based on an in silico study, which suggested that its interaction with specific protein targets of C. acnes may contribute to its synergistic antibacterial and anti-inflammatory effects. To achieve our aim, glycerosomes were fabricated with the incorporation of lauric acid as a main constituent of glycerosomes vesicular membrane along with cholesterol and phospholipon 90H, while lincomycin was entrapped within the aqueous cavities. Glycerol is expected to enhance the cutaneous absorption of the active moieties via hydrating the skin. Optimization of lincomycin-loaded glycerosomes (LM-GSs) was conducted using a mixed factorial experimental design. The optimized formulation; LM-GS4 composed of equal ratios of cholesterol:phospholipon90H:Lauric acid, demonstrated a size of 490 ± 17.5 nm, entrapment efficiency-values of 90 ± 1.4 % for lincomycin, and97 ± 0.2 % for lauric acid, and a surface charge of -30.2 ± 0.5mV. To facilitate its application on the skin, the optimized formulation was incorporated into a carbopol hydrogel. The formed hydrogel exhibited a pH value of 5.95 ± 0.03 characteristic of pH-balanced skincare and a shear-thinning non-Newtonian pseudoplastic flow. Skin deposition of lincomycin was assessed using an in-house developed and validated LC-MS/MS method employing gradient elution and electrospray ionization detection. Results revealed that LM-GS4 hydrogel exhibited a two-fold increase in skin deposition of lincomycin compared to lincomycin hydrogel, indicating improved skin penetration and sustained release. The synergistic healing effect of LM-GS4 was evidenced by a reduction in inflammation, bacterial load, and improved histopathological changes in an acne mouse model. In conclusion, the proposed formulation demonstrated promising potential as a topical treatment for acne. It effectively enhanced the cutaneous absorption of lincomycin, exhibited favorable physical properties, and synergistic antibacterial and healing effects. This study provides valuable insights for the development of an effective therapeutic approach for acne management.

DeoR regulates lincomycin production in Streptomyces lincolnensis.

Regulators belonging to the DeoR family are widely distributed among the bacteria. Few studies have reported that DeoR family proteins regulate secondary metabolism of Streptomyces. This study explored the function of DeoR (SLINC_8027) in Streptomyces lincolnensis. Deletion of deoR in NRRL 2936 led to an increase in cell growth. The lincomycin production of the deoR deleted strain ΔdeoR was 3.4-fold higher than that of the wild strain. This trait can be recovered to a certain extent in the deoR complemented strain ΔdeoR::pdeoR. According to qRT-PCR analysis, DeoR inhibited the transcription of all detectable genes in the lincomycin biosynthesis cluster and repressed the expression of glnR, bldD, and SLCG_Lrp, which encode regulators outside the cluster. DeoR also inhibited the transcription of itself, as revealed by the XylE reporter. Furthermore, we demonstrated that DeoR bound directly to the promoter region of deoR, lmbA, lmbC-D, lmbJ-K, lmrA, lmrC, glnR, and SLCG_Lrp, by recognizing the 5'-CGATCR-3' motif. This study found that versatile regulatory factor DeoR negatively regulates lincomycin biosynthesis and cellular growth in S. lincolnensis, which expanded the regulatory network of lincomycin biosynthesis.

Impact of buffered sodium butyrate as a partial or total dietary alternative to lincomycin on performance, IGF-1 and TLR4 genes expression, serum indices, intestinal histomorphometry, Clostridia, and litter hygiene of broiler chickens.

BACKGROUND: Sodium butyrate (SB) is a short-chain fatty acid and a safe antibiotic alternative. During 35 days, this study compared the impact of coated SB (Butirex C4) and lincomycin (Lincomix) on broiler growth, gut health, and litter hygiene in 1200 one-day-old Ross-308 broiler chicks that were randomly assigned into 5-dietary groups with 5-replications each. Groups divided as follows: T1: Basal diet (control), T2: Basal diet with buffered SB (1 kg/ton starter feed, 0.5 kg/ton grower-finisher feeds), T3: Basal diet with 100 g/ton lincomycin, T4: Basal diet with buffered SB (0.5 kg/ton starter feed, 0.25 kg/ton grower-finisher feeds) + 50 g/ton lincomycin, and T5: Basal diet with buffered SB (1 kg/ton starter feed, 0.5 kg/ton grower-finisher feeds) + 50 g/ton lincomycin. Birds were housed in a semi-closed deep litter house, where feed and water were available ad libitum. Results were statistically analyzed using ANOVA and Tukey's post hoc tests. RESULTS: Combined dietary supplementation with SB and lincomycin (T4 and T5) significantly enhanced body weights, weight gains, feed conversion ratio, and profitability index. Also, carcasses in T4 and T5 exhibited the highest dressing, breast, thigh, and liver yields. T5 revealed the best blood biochemical indices, while T3 showed significantly elevated liver and kidney function indices. T4 and T5 exhibited the highest expression levels of IGF-1 and TLR4 genes, the greatest villi length of the intestinal mucosa, and the lowest levels of litter moisture and nitrogen. Clostridia perfringens type A alpha-toxin gene was confirmed in birds' caeca, with the lowest clostridial counts defined in T4. CONCLUSIONS: Replacing half the dose of lincomycin (50 g/ton) with 0.5 or 1 kg/ton coated SB as a dietary supplement mixture showed the most efficient privileges concerning birds' performance and health.

LcbR1, a newly identified GntR family regulator, represses lincomycin biosynthesis in Streptomyces lincolnensis.

The Actinomycetes Streptomyces lincolnensis is the producer of lincosamide-type antibiotic lincomycin, a widely utilized drug against Gram-positive bacteria and protozoans. In this work, through gene knockout, complementation, and overexpression experiments, we identified LcbR1 (SLINC_1595), a GntR family transcriptional regulator, as a repressor for lincomycin biosynthesis. Deletion of lcbR1 boosted lincomycin production by 3.8-fold, without obvious change in morphological development or cellular growth. The homologues of LcbR1 are widely distributed in Streptomyces. Heterologous expression of SCO1410 from Streptomyces coelicolor resulted in the reduction of lincomycin yield, implying that the function of LcbR1 is conserved across different species. Alignment among sequences upstream of lcbR1 and their homologues revealed a conserved 16-bp palindrome (-TTGAACGATCCTTCAA-), which was further proven to be the recognition motif of LcbR1 by electrophoretic mobility shift assays (EMSAs). Via this motif, LcbR1 suppressed the transcription of lcbR1 and SLINC_1596 sharing the same bi-directional promoter. SLINC_1596, one important target of LcbR1, exerted a positive effect on lincomycin production. As detected by quantitative real-time PCR (qRT-PCR) analyses, the expressions of all selected structural (lmbA, lmbC, lmbJ, lmbV, and lmbW), resistance (lmrA and lmrB) and regulatory genes (lmrC and lmbU) from lincomycin biosynthesis cluster were upregulated in deletion strain ΔlcbR1 at 48 h of fermentation, while the mRNA amounts of bldD, glnR, ramR, SLCG_Lrp, and SLCG_2919, previously characterized as the regulators on lincomycin production, were decreased in strain ΔlcbR1, although the regulatory effects of LcbR1 on the above differential expression genes seemed to be indirect. Besides, indicated by EMSAs, the expression of lcbR1 might be regulated by GlnR, SLCG_Lrp, and SLCG_2919, which shows the complexity of the regulatory network on lincomycin biosynthesis. KEY POINTS: • LcbR1 is a novel and conservative GntR family regulator regulating lincomycin production. • LcbR1 modulates the expressions of lcbR1 and SLINC_1596 through a palindromic motif. • GlnR, SLCG_Lrp, and SLCG_2919 can control the expression of lcbR1.