Bioactivities of endophytic actinobacteria inhabiting Artemisia herba-alba emphasizing differences from free-living strains.

The endophytic actinobacteria associated with Artemisia herba-alba (synonym: Seriphidium herba-alba) are highly diverse. This study aimed to illustrate the extent of their differences from the free-living actinobacteria in the surrounding environment. A selection of eighteen actinobacteria inhabiting A. herba-alba were compared with twenty and ten actinobatceria isolates from the surrounding desert and groundwater, respectively, representing six genera. Antagonistic and enzymatic activities, plant growth-promoting traits, and the occurrence of biosynthetic genes were compared among the isolates. Data were analyzed statistically using principal component analysis (PCA) and were visualized using heat map. Endophytic strains showed higher antimicrobial activity and production of plant growth promoters compared to desert and groundwater strains. Polyketide synthase and non-ribosomal peptide synthetase gene clusters were detected at higher frequencies in the endophytic strains (8 and 11 strains, respectively) than the desert strains (1 and 2 strains, respectively). In contrast, both gene clusters were not detected in the groundwater strains. The PCA revealed unique metabolic characteristics of the endophytes. The heatmap clustered the endophytic strains apart from the free-living strains, indicating distinctive qualitative and quantitative bioactivities. Analysis of 16S rRNA genes confirmed the chemotaxonomic identity of all but two strains, with > 94.5% similarity. Six endophytes displayed < 99.5% similarity with their closest type strains, which might indicate species novelty. This study provides an evidence of functional differences and possible species novelty of the endophytic actinobacteria inhabiting A. herba-alba, compared with the free-living species.

Virulence-determinants and antibiotic-resistance genes of MDR-E. coli isolated from secondary infections following FMD-outbreak in cattle.

This study aimed to evaluate the prevalence, multidrug-resistance traits, PCR-detection of virulence, and antibiotic-resistance genes of E. coli isolated from secondary infections following FMD-outbreak in cattle. A total of 160 random samples were gathered from private dairy farms in Damietta Province, Egypt. The specimens were subjected to bacteriological examination, serotyping, congo-red binding assay, antibiogram-testing, and PCR-monitoring of virulence-determinant genes (tsh, phoA, hly, eaeA, sta, and lt) as well as the antibiotic-resistance genes (blaTEM, blaKPC, and blaCTX). The prevalence of E. coli was 30% (n = 48) distributed in 8 serogroups (40/48, 83.3%), while 8 isolates (8/48, 16.6%) were untypable. Besides, 83.3% of the examined isolates were positive for CR-binding. The tested strains harbored the virulence genes phoA, hly, tsh, eaeA, sta, and lt with a prevalence of 100% and 50%, 45.8%, 25%, 8.4%, and 6.2%, respectively. Furthermore, 50% of the recovered strains were multidrug-resistant (MDR) to penicillins, cephalosporins, and carbapenems, and are harboring the blaTEM, blaCTX, and blaKPC genes. Moreover, 25% of the examined strains are resistant to penicillins, and cephalosporins, and are harboring the blaTEM and blaCTX genes. To the best of our knowledge, this is the first report concerning the E. coli secondary bacterial infections following the FMD-outbreak. The emergence of MDR strains is considered a public health threat and indicates complicated treatment and bad prognosis of infections caused by such strains. Colistin sulfate and levofloxacin have a promising in vitro activity against MDR-E. coli.

Molecular Typing, Antibiogram and PCR-RFLP Based Detection of Aeromonas hydrophila Complex Isolated from Oreochromis niloticus.

Motile Aeromonas septicemia is a common bacterial disease that affects Oreochromis niloticus and causes tremendous economic losses globally. In order to investigate the prevalence, molecular typing, antibiogram and the biodiversity of Aeromonas hydrophila complex, a total of 250 tilapia (Oreochromis niloticus) were collected randomly from 10 private tilapia farms (25 fish/farm) at El-Sharkia Governorate, Egypt. The collected fish were subjected to clinical and bacteriological examinations. The majority of infected fish displayed ulcerative necrosis, exophthalmia, and internal signs of hemorrhagic septicemia. The prevalence of A. hydrophia complex was 13.2%, where the liver was the most predominant affected organ (54.1%). Polymerase chain reaction (PCR) was used to verify the identification of A. hydrophila complex using one set of primers targeting gyrB as well as the detection of virulent genes (aerA, alt, and ahp). All isolates were positive for the gyrB-conserved gene and harbored aerA and alt virulence genes. However, none of those isolates were positive for the ahp gene. The antimicrobial sensitivity was carried out, where the recovered strains were completely sensitive to ciprofloxacin and highly resistant to amoxicillin. All retrieved strains showed the same phenotypic characteristics and were identical based on the restriction fragment length polymorphism (RFLP). Experimentally challenged fish presented a high mortality rate (76.67%) and showed typical signs as in naturally infected ones. In conclusion, the synergism of phenotypic and genotypic characterization is a valuable epidemiological tool for the diagnosis of A. hydrophila complex. RFLP is a fundamental tool for monitoring the biodiversity among all retrieved strains of A. hydrophia.

Generic and functional diversity in endophytic actinomycetes from wild Compositae plant species at South Sinai - Egypt.

The diversity of culturable endophytic actinomycetes associated with wild Compositae plants is scantily explored. In this study, one hundred and thirty one endophytic actinobacteria were isolated from ten Compositae plant species collected from South Sinai in Egypt. Microscopic and chemotaxonomic investigation of the isolates indicated fourteen genera. Rare genera, such as Microtetraspora, and Intrasporangium, which have never been previously reported to be endophytic, were identified. Each plant species accommodated between three to eight genera of actinobacteria and unidentified strains were recovered from seven plant species. The generic diversity analysis of endophytic assemblages grouped the plant species into three main clusters, representing high, moderate and low endophytic diversity. The endophytes showed high functional diversity, based on forty four catabolic and plant growth promotion traits; providing some evidence that such traits could represent key criteria for successful residence of endophytes in the endosphere. Stress-tolerance traits were more predictive measure of functional diversity differences between the endophyte assemblages (Shannon's index, p = 0.01). The results indicate a potential prominent role of endophytes for their hosts and emphasize the potency of plant endosphere as a habitat for actinobacteria with promising future applications.