Persistence of G10P[11] neonatal rotavirus infections in southern India

ABSTRACTNeonatal rotavirus infections are predominantly caused by distinct genotypes restricted to this age-group and are mostly asymptomatic. Stool samples from neonates admitted for >48 hours in neonatal intensive care units (NICUs) in Vellore (2014-2015) and Chennai (2015-2016) in southern India, and from neonates born at hospitals in Vellore but not admitted to NICUs (2015-2016) were tested for rotavirus by ELISA and genotyped by hemi-nested RT-PCR. Of the 791 neonates, 150 and 336 were recruited from Vellore and Chennai NICUs, and 305 were born in five hospitals in Vellore. The positivity rates in the three settings were 49.3% (74/150), 29.5% (99/336) and 54% (164/305), respectively. G10P[11] was the commonly identified genotype in 87.8% (65/74), 94.9% (94/99) and 98.2% (161/164) of the neonates in Vellore and Chennai NICUs, and those born at Vellore hospitals, respectively. Neonates delivered by lower segment caesarean section (LSCS) at Vellore hospitals, not admitted to NICUs, had a significantly higher odds of acquiring rotavirus infection compared to those delivered vaginally [p=0.002, OR=2.4 (1.4-4.3)]. This report demonstrates the persistence of G10P[11] strain in Vellore and Chennai, indicating widespread neonatal G10P[11] strain in southern India and their persistence over two decades, leading to interesting questions about strain stability.

Promising Anti-MRSA Activity of Brevibacillus sp. Isolated from Soil and Strain Improvement by UV Mutagenesis

Antibiotic-resistant infection is a major health problem, and a limited number of drugs are currently approved as antibiotics. Soil bacteria are promising sources in the search for novel antibiotics. The aim of the present study is to isolate and assess soil bacteria with anti-MRSA activity and improve their capabilities by UV mutagenesis. Soil samples from the upper south of Thailand were screened for antibacterial activity using the cross-streak method. Agar well diffusion was used to examine the activity of isolates against a spectrum of human pathogens. The most active isolate was identified by 16S rRNA sequencing, and the production kinetics and stability were investigated. The most promising isolate was mutated by UV radiation, and the resulting activity and strain stability were studied. The results show that isolates from the cross-streak method could inhibit Staphylococcus aureus TISTR 517 (94 isolates) and Escherichia coli TISTR 887 (67 isolates). Nine isolates remained active against S. aureus TISTR 517 and MRSA, and eight isolates inhibited the growth of E. coli TISTR 887 as assessed using agar well diffusion. The most active strain was Brevibacillus sp. SPR-20, which had the highest activity at 24 h of incubation. The active substances in culture supernatants exhibited more than 90% activity when subjected to treatments involving various heat, enzymes, surfactants, and pH conditions. The mutant M201 showed significantly higher activity (109.88–120.22%) and strain stability compared to the wild-type strain. In conclusion, we demonstrate that soil Brevibacillus sp. is a potential resource that can be subjected to UV mutagenesis as a useful approach for improving the production of anti-MRSA in the era of antibiotic resistance.

Strain-Level Analysis of Bifidobacterium spp. from Gut Microbiomes of Adults with Differing Lactase Persistence Genotypes

When humans domesticated animals, some adapted genetically to digest milk into adulthood (lactase persistence). The gut microbiomes of people with lactase-persistent genotypes (AA or AG) differ from those with lactase-nonpersistent genotypes (GG) by containing fewer bacteria belonging to the bifidobacteria, a group which contains beneficial species. Here, we asked if the gut microbiomes of adults with GG and AA/AG genotypes differ in the species of bifidobacteria present. In particular, we used a novel technique which allowed us to compare bifidobacteria in adults at the strain level, without the traditional need for culturing. Our results show that the GG genotype enhances the abundance of bifidobacteria regardless of species. We also noted that a person’s specific strains are recoverable several years later, and twins can share the same ones. Given that bifidobacteria are inherited from mother to child, strain stability over time in adulthood suggests long-term, multigenerational inheritance.

The mechanism of stability of fault system inducing roof water-inrush

This paper analyzes the strain stability during mining, which often causes a water inrush. Mining couses costant stress on the fault zone, which is a loading process on the system composed of fault material and surrounding medium. A cusp catastrophe model is presented and the necessary and sufficient conditions leading to fault systems are discussed. The fault zone is assumed to be planar and is a combination of two media: medium-1 is elastic-brittle or strain-hardening and medium-2 is strain-softening. The shear stress-strain constitutive model for the strain-softening medium is described by the Weibull’s distribution law. It was found that the instability of a fault system mainly relies on the ratio between the stiffness of medium1 to the post-peak stiffness of the strain-softening medium, and the homogeneity index of strain-softening medium and the bifurcation point, k ≤ 1, which is the turning point of the fault system from stability to potential instability. One can judge the occurrence of fault instability from this feature and regard the index D as a parameter, which reflects the precursory abnormality of a fault.

Coupling metabolic addiction with negative autoregulation to improve strain stability and pathway yield

Metabolic addiction, an organism that is metabolically addicted with a compound to maintain its growth fitness, is an underexplored area in metabolic engineering. Microbes with heavily engineered pathways or genetic circuits tend to experience metabolic burden leading to degenerated or abortive production phenotype during long-term cultivation or scale-up. A promising solution to combat metabolic instability is to tie up the end-product with an intermediary metabolite that is essential to the growth of the producing host. Here we present a simple strategy to improve both metabolic stability and pathway yield by coupling chemical addiction with negative autoregulatory genetic circuits. Naringenin and lipids compete for the same precursor with inversed pathway yield in oleaginous yeast. Negative autoregulation of the lipogenic pathways, enabled by CRISPRi and fatty acid-inducible promoters, repartitioned malonyl-CoA to favor flavonoid synthesis and increased naringenin production by 74.8%. With flavonoid-sensing hybrid promoters to control leucine synthesis, this flavonoid addiction phenotype confers a selective growth advantage to the naringenin-producing cell. The engineered yeast persisted 90.9% of naringenin titer up to 324 generations. Cells without flavonoid addiction regained growth fitness but lost 94.5% of the naringenin titer after cell passage beyond 300 generations. Metabolic addiction and negative autoregulation may be generalized as basic tools to eliminate metabolic heterogeneity, improve strain stability and pathway yield.