Role of Maize Root Exudates in Promotion of Colonization of Bacillus velezensis Strain S3-1 in Rhizosphere Soil and Root Tissue.

Bacillus velezensis strain S3-1 has a broad range of hosts and is used as a biocontrol agent and biofertilizer. However, the interaction of maize root exudates and colonization of the strain S3-1 has not yet been investigated. In our study, strain S3-1 effectively colonized both rhizosphere soil and root tissue. Collected maize root exudates significantly induced the chemotaxis, cluster movement, and biofilm formation of strain S3-1, showing increases of 1.43, 1.6, and 2.08 times, respectively, compared with the control. In addition, the components of root exudates (organic acids: citric acid, malic acid, and oxalic acid; amino acids: glycine, proline and phenylalanine; sugars: glucose, fructose, and sucrose) were tested. Each of these compounds could induce chemotactic response, swarming motility, and biofilm formation significantly. The strongest chemotactic response and swarming motility were found when malic acid was applied, but maximal ability of biofilm formation was stimulated by proline. Furthermore, we found that these compounds of root exudates stimulated the population of S3-1 adhering to the maize root surface, especially in the presence of malic acid. These results indicate that maize root exudates play an important role in the colonization of S3-1, and provide a deeper understanding of the interaction between plants and microorganisms.

Effect of plants and their root exudate on bacterial activities during rhizobacterium-plant remediation of phenol from water.

We investigated remediation of phenol from water using microbe-plant partnerships. Co-introduction of maize seedlings, Pseudomonas fluorescens rifampicin-resistant P13 and P. stutzeri P7 carrying self-transmissible TOL-like plasmids reduced phenol content in water at lower phenol concentrations (25, 50, and 75 mg/L), similar to individual introduction of the bacteria. Co-introduction of plants and bacteria significantly reduced phenol content in water at higher phenol concentrations (100, 125, and 150 mg/L) compared to using individual introduction of the bacteria. Moreover, TOL-like plasmids were transferred from P7 to P13. Addition of plants promoted the growth of both strains, leading to increased plasmid transfer. At higher phenol concentrations, addition of plants resulted in increases of catechol 2, 3-dioxygenase (C23O) activity and reduction in level of reactive oxygen species (ROS) of bacteria in the degradation experiments. Increased plasmid transfer and C23O activity and reduction in ROS level might be the major reasons why plants promote bacterial degradation of phenol at higher phenol concentrations. Furthermore, root exudate of maize seedlings and artificial root exudate (ARE) constructed using major components of the root exudate had the same effects on bacterial activities. Unlike the ARE, deletion of glucose, arabinose, or fructose or all the monosaccharides from ARE resulted in no increase in numbers of both strains and in plasmid transfer. At the higher phenol concentrations, deletion of glutamic acid, aspartic acid, alanine, or glycine or all the amino acids did not stimulate bacterial C23O activity. Deletion of fumaric, oxaloacetic or citric acids still reduced bacterial ROS level as ARE did, but, deletion of all the organic acids or DIMBOA, a hydroxamic acid, did not reduce bacterial ROS level as ARE did. The data showed that each monosaccharide might be important for sufficient numbers of plant-associated bacteria and increased plasmid transfer while each amino acid might be important for maintaining bacterial C23O activity and that DIMBOA might be responsible for the decrease in ROS levels. These results are the basis for efficient remediation of phenol from water by microbe-plant partnerships and further studies on the mechanism of rhizobacterium-plant interaction.

Blood group AB is protective factor for gestational diabetes mellitus: a prospective population-based study in Tianjin, China.

BACKGROUND: The ABO blood types are associated with cancers, cardiovascular diseases and type 2 diabetes mellitus but whether they are also associated with gestational diabetes mellitus (GDM) is unknown. We examined the relationship between the ABO blood types and the risk of GDM in a prospective population-based Chinese cohort. METHODS: From 2010 to 2012, we recruited 14,198 pregnant women within the first 12 weeks of gestation in Tianjin, China. All women had a glucose challenge test (GCT) at 24-28 gestational weeks, followed by a 75-g 2-h oral glucose tolerance test if the results from GCT were ≥7.8 mmol/L. GDM was diagnosed based on the glucose cut-points of the International Association of Diabetes and Pregnancy Study Group criteria. Logistic regression was used to obtain odds ratios (ORs) and 95% confidence intervals (CIs) adjusted for traditional risk factors. Stratified analysis was performed by family history of diabetes (yes versus no). Sensitivity analyses were also performed by using the World Health Organization (WHO) criteria for GDM. RESULTS: Women with blood groups A, B or O (i.e. non-AB) were associated with increased risk of GDM as compared with those with blood group AB (adjusted OR: 1.44, 95% CI: 1.13-1.83). Sensitivity analyses showed that the result was consistent using WHO criteria. The adjusted OR of blood group non-AB versus AB for GDM was enhanced among women with a family history of diabetes (2.69, 1.21-5.96) and attenuated among those without (1.33, 1.03-1.71). CONCLUSIONS: Blood group AB was a protective factor against GDM in pregnant Chinese women.

Maternal OGTT glucose levels at 26-30 gestational weeks with offspring growth and development in early infancy.

AIMS: We aim to evaluate the association of maternal gestational oral glucose tolerance test (OGTT) glucose concentrations with anthropometry in the offspring from birth to 12 months in Tianjin, China. METHODS: A total of 27,157 pregnant women underwent OGTT during 26-30 weeks gestation, and their children had body weight/length measured from birth to 12 months old. RESULTS: Maternal OGTT glucose concentrations at 26-30 gestational weeks were positively associated with Z-scores for birth length-for-gestational age and birth weight-for-length. Compared with infants born to mothers with normal glucose tolerance, infants born to mothers with gestational diabetes mellitus (impaired glucose tolerance/new diabetes) had higher mean values of Z-scores for birth length-for-gestational age (0.07/0.23; normal group -0.08) and birth weight-for-length (0.27/0.57; normal group -0.001), smaller changes in mean values of Z-scores for length-for-age (0.75/0.62; normal group 0.94) and weight-for-length (0.18/-0.17; normal group 0.37) from birth to month 3, and bigger changes in mean values in Z-scores for weight-for-length (0.07/0.12; normal group 0.02) from month 9 to 12. CONCLUSIONS: Abnormal maternal glucose tolerance during pregnancy was associated with higher birth weight and birth length, less weight and length gain in the first 3 months of life, and more weight gain in the months 9-12 of life.

Birth weight and overweight or obesity risk in children under 3 years in China.

OBJECTIVE: To investigate the association between different levels of birth weight and the risk of overweight and obesity in children aged 3 years and under. METHODS: Between 2009 and 2011, health care records of 55,925 children had been collected, and body weight and length had been measured from birth to 3 years old. RESULTS: Prevalence of overweight/obesity (BMI ≥85th percentiles and BMI ≥95th percentiles, referring to WHO BMI standards) at 0.5, 1, 2, and 3 years of age are 34.7%/16.8%, 36.4%/17.7%, 26.6%/11.0%, 22.3%/9.3%, respectively. There was a positive association between birth weight and childhood overweight or obesity from 6 months to 3 years of age. After adjustment for gestational age, maternal age, weight gain during pregnancy, maternal history of diabetes, mother's and father's education, occupation, and health status, family income, feeding modalities, and sex, the odds ratios (ORs) of overweight or obesity were significantly higher among children whose birth weights were 3,000-3,499 g (1.35-1.53 folds), 3,500-3,999 g (2.09-2.37 folds), 4,000-4,499 g (2.80-3.32 folds), and more than 4,500 g (3.54-4.90 folds), compared with the reference group (2,500-2,999 g). CONCLUSIONS: Higher levels of birth weight were associated with an increased risk of overweight or obesity among Chinese children from 6 months to 3 years of age.