Effects of antibiotics on the development and intestinal bacterial diversity of black soldier fly larvae

The effects of four antibiotics (metronidazole (M) levofloxacin (L), sodium ampicillin (A), and streptomycin sulphate (S)) and their pair-wise combinations at three doses on the development and intestinal bacterial diversity of the black soldier fly (BSF; Hermetia illucens) larvae were studied. At a low dose M and L were able to inhibit larval growth. At a high dose, all antibiotics were shown to inhibit larval growth. However, the pair-wise combinational use of the antibiotics did not effectively enhance the inhibitory effect. The gut bacterial diversity of the normal control (NC) was significantly higher than the antibiotic-treated groups with 737 operational taxonomic units (OTUs) from the larval guts of NC, compared to 305 and 227 from ML and AS. The number of anaerobic bacteria in ML was significantly lower than in NC and AS, with the relative abundance of OTUs from larval guts of ML being only about 0.01, compared to 0.4 for NC and 0.15 for AS. These results indicated that antibiotics at the experimental concentration did not affect the palatability of food for insects, but they would affect the diversity of food and intestinal microorganisms of BSF larvae, and the inhibitory effect of antibiotics on growth and development of BSF larvae displayed in this study was a complex effect.

Bacillus-based products for management of kiwifruit bacterial canker

Pseudomonas syringae pv. actinidiae is an important pathogen of kiwifruit (Actinidia deliciosa), and bacterial canker of this host is managed by monitoring and chemical control strategies. The efficacy of the bio-pesticides Amylo-X® (based on Bacillus amyloliquefaciens subsp. plantarum strain D747) and Serenade Max® (strain QST713 of B. subtilis) was evaluated by in vitro and in vivo experiments. Both antagonists inhibited different biovars of the pathogen in in vitro assays; QST713 was more efficient than D747. The two Bacillus strains also colonized A. deliciosa flowers (c. 105-7 cfu per flower) up to 96 h after inoculation. D747 persisted on leaves (c. 104-6 cfu cm-2) up to 4 weeks after inoculation, during 2 years in Emilia Romagna and Latium regions of Italy. On flowers, the antagonists reduced pathogen populations, compared to untreated (control) flowers. On A. deliciosa and A. chinensis plants under controlled conditions, Amylo-X® reduced severity of bacterial canker, providing ca. 50% relative protection on A. deliciosa and 70% on A. chinensis. Serenade Max® was less effective, giving 0% relative protection on A. deliciosa and 40% on A. chinensis. In a field trial, on A. deliciosa plants, Amylo-X® reduced the severity of bacterial canker on leaves, providing ca. 40% relative protection. The sensitivity of both antagonistic strains to streptomycin sulphate was confirmed by testing the most used concentration where antibiotics are approved for management of bacterial pathogens.

Genomic Insights Into Antibiotic Resistance Pattern of Tetracycline Degrading Bacterium Arthrobacter Nicotianae OTC-16

Although many bacteria have the potential to remove antibiotic residues from environmental niches, the benefits of using antibiotic degrading bacteria to manage antibiotic pollution should be assessed against the risk of the potential expansion of antimicrobial resistance. This study investigated the antibiotic resistance pattern of the bacterium Arthrobacter nicotianae OTC 16, which shows substantial biodegradation of oxytetracycline/tetracycline. The results showed that this strain could be resistant to at least seven categories, 15 antibiotics, based on antimicrobial susceptibility testing. The genome of A. nicotianae OTC 16 contains one chromosome(3,643,989 bp) and two plasmids (plasmid1,123,894 bp and plasmid2, 29,841bp). Of the 3,561 genes isolated, eight were related to antibiotic resistance. During oxytetracycline (OTC) degradation by the strain OTC 16, the expression of ant2ia, sul1, tet33, and cml_e8 in the plasmid, and one gene(tetV) in the chromosome were tracked by real time quantitative reverse transcription polymerase chain reaction(qRT PCR). Only the plasmid derived resistance genes were up regulated under the pressure of OTC. The presence of OTC increased the tolerance of strain OTC 16 to streptomycin sulphate. This work deepens our understanding of the behavioural characteristics of resistance genes and adaptive evolution of resistant drug bacteria under the pressure of antibiotics.

Selection of Rhizobium spp. Isolates for Inoculation of Field Pea (Pisum sativum)

Rhizobium isolates from wild pea nodules were characterized on the basis of microbiological characteristics. P4, P7, P12, P14, P16, P19, P20, P22, P23 and P24 isolates grew at the 4.5 pH, P5, P6, P11, P12, P13, P14, P16, P17, P19, P20 and P21 isolates grew at 4% NaCl and P7, P8, P10, P11, P12, P14, P19, P20, P22, P23, P24 and P25 isolates grew at 40°C. Resistance to antibiotics (μg mL-1) was investigated in a large propotion of isolates; streptomycin sulphate (80), rifampisin (40), erythromycin (30), chloramphenicol (100), Penicillin (40). In this study, local Rhizobium bacterial isolates were isolated from wild pea root nodules and their efficacy was investigated. Isolates significantly increased plant dry matter weight. The highest nitrogen fixation was achieved with P4 inoculation. Glutamine synthetase and leghemoglobin content of the nodules were determined in the inoculated with the highest P4 isolate. © 2021 Friends Science Publishers

51 Comparison of SexedULTRA 4M and conventional semen for invitro production of bovine embryos using two bulls

SexedULTRA 4M™ (Select Sires) is made using an improved method of sex-sorting sperm in a less damaging environment for retaining sperm integrity through the sorting process. The combination of invitro embryo production (IVP) and sexed semen technologies has been successful for intensity selection in the cattle industry. The objective of this research was to compare conventional (CONV) and SexedULTRA 4M (ULTRA-4M) semen for bovine IVP using 2 bulls. The research was carried out in the reproduction laboratory at Palominos Ranch (Jalisco, México). The IVP was performed with a continuous invitro culture system. Ovaries from commercial cattle (n=213) were collected from a slaughterhouse (León, México) and transported to the laboratory within 2h in physiological saline solution (0.9% NaCl) supplemented with penicillin G (100IUmL−1) and streptomycin sulphate (100µg mL−1). For IVP, IVF Bioscience™ media were used for IVM, IVF, and invitro culture (IVC). For the IVM, the cumulus–oocyte complexes (COCs) were selected (grades 1 and 2) and matured for 24h at 38.5°C in 5% CO2 in air and 100% humidity. Matured oocytes (n=1200, divided equally into 3 replicates) were divided into 2 groups, the CONV group and the ULTRA-4M group. The IVF process was conducted with both CONV and ULTRA-4M semen from the 2 bulls, separately, at an adjusted concentration of 2×106 and 0.5×106 sperm mL−1, respectively, for 18h in 38.5°C, 5% CO2 in air, and 100% humidity. The presumptive zygotes were denuded by pipetting and set in IVC until Day 7 at 38.5°C, 5% CO2, 5% O2 and 90% N2 at 100% humidity. The cleavage rate, embryos with more than 6 cells, and blastocysts on Day 7 of culture were evaluated. Statistical analysis was carried out with the GLM procedure of SAS (version 9.3; SAS Institute Inc.) to evaluate the results of CONV versus ULTRA-4M for each bull (α level=0.05). Cleavage rates were 57.1%±1.5 and 59.4%±1.5, respectively in CONV and ULTRA-4M groups with Bull 1 and 43.3%±1.5 and 45.2%±1.5 with Bull 2. The percentages of embryos with more than 6 cells were 51.4%±1.0 and 53.9%±1.0, respectively, with CONV and ULTRA-4M with Bull 1 and 30.4%±1.0 and 33.4%±1.0 with Bull 2. The percentage of blastocysts on Day 7 with Bull 1 was 34.4%±1.7 for CONV and 36.2%±1.7 for ULTRA-4M; for Bull 2, the results were 26.5%±1.7 for CONV and 29.5%±1.7 for ULTRA-4M. There were no significant differences between the CONV and ULTRA-4M groups (P>0.05) for all variables analysed for each bull; however, Bull 1 was significantly superior to Bull 2 for all variables analysed. In conclusion, under the conditions of this research, ULTRA-4M and CONV semen produced similar bovine IVP results.