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Microbial graphene oxide reduction is a developing method that serves to reduce both production costs and environmental impact in the synthesis of graphene. This study demonstrates microbial graphene oxide reduction using Shewanella decolorationis NTOU1 under neutral and mild conditions (pH = 7, 35 °C, and 1 atm). Graphene oxide (GO) prepared via the modified Hummers' method is used as the sole solid electron acceptor, and the characteristics of reduced GO (rGO) are investigated. According to electron microscopic images, the surface structure of GO was clearly changed from smooth to wrinkled after reduction, and whole cells were observed to be wrapped by GO/rGO films. Distinctive appendages on the cells, similar to nanowires or flagella, were also observed. With regard to chemical-bonding changes, after a 24-h reaction of 1 mg mL-1, GO was reduced to rGO, the C/O increased from 1.4 to 3.0, and the oxygen-containing functional groups of rGO were significantly reduced. During the GO reduction process, the number of S. decolorationis NTOU1 cells decreased from 1.65 × 108 to 1.03 × 106 CFU mL-1, indicating the bactericide effects of GO/rGO. In experiments adding consistent concentrations of initial bacteria and lactate, it was shown that with the increase of GO additions (0.5-5.0 mg mL-1), the first-order reaction rate constants (k) of lactate metabolism and acetate production increased accordingly; in experiments adding consistent concentrations of initial bacteria and GO but different lactate levels (1 to 10 mM), the k values of lactate metabolism did not change significantly. The test results of adding different electron transfer mediators showed that riboflavin and potassium ferricyanide were able to boost GO reduction, whereas 2,6-dimethoxy-1,4-benzoquinone and 2,6-dimethyl benzoquinone completely eliminated bacterial activity.
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BACKGROUND: Although numerous studies have examined the development of preterm children born very low birth weight (VLBW, birth body weight < 1500 g), variations of developmental progress within individuals have rarely been explored. The aim of this research was to examine the cognitive and motor trajectories in preterm children born VLBW at early ages and to assess the risk factors and predictability of these trajectories. METHOD: Five hundred and eighty preterm infants born VLBW from three cohort studies (2003 to 2014) were prospectively assessed their mental and motor development using the Bayley Scales at 6, 12, 24, and 36 months, and cognitive, motor and behavioral outcomes using the Movement Assessment Battery for Children and the Child Behavior Checklist for Ages 1.5-5 at 4 years of age. RESULTS: Preterm children born VLBW manifested three cognitive patterns (stably normal [64.0 %], deteriorating [31.4 %], and persistently delayed [4.6 %]) and four motor patterns (above average [6.3 %], stably normal [60.0 %], deteriorating [28.5 %], and persistently delayed [5.2 %]) during 6-36 months. Low birth body weight, stage III-IV retinopathy of prematurity and low parental socio-economic status were associated with the deteriorating patterns; prolonged hospitalization and major brain damage were additionally associated with the persistently delayed patterns. Furthermore, the cognitive and motor deteriorating pattern was each predictive of cognitive and motor impairment at 4 years of age; whereas, the persistently delayed patterns were predictive of multiple impairments. CONCLUSION AND IMPLICATIONS: Preterm children born VLBW display heterogeneous trajectories in early cognitive and motor development that predict subsequent developmental and behavioral outcomes.