Enzymatic phosphorylation of mannose by glucomannokinase from Mycobacterium phlei using inorganic polyphosphate

Low and high nucleic acid content bacteria play discrepant roles in response to various carbon supply modes

Planktonic bacteria can be grouped into 'high nucleic acid content (HNA) bacteria' and 'low nucleic acid content (LNA) bacteria.' Nutrient input modes vary in environments, causing nutrient availability heterogeneity. We incubated them with equal amounts of total glucose added in a continuous/pulsed mode. The pulse-treated LNA bacteria exhibited twice the cell abundance and four times the viability of the continuous-treated LNA, while HNA did not show an adaptation to pulsed treatment. In structural equation modelling, LNA bacteria had higher path coefficients than HNA, between growth and carbon-saving metabolic pathways, intracellular ATP and the inorganic energy storage polymer, polyphosphate, indicating their low-cost growth, and flexible energy storage and utilisation. After incubation, the pulse-treated LNA bacteria contained more proteins and polysaccharides (0.00064, 0.0012 ng cell-1 ) than the continuous-treated LNA (0.00014, 0.00014 ng cell-1 ), conferring endurance and rapid response to pulses. Compared to LNA, HNA keystone taxa had stronger correlations with the primary glucose metabolism step, glycolysis, and occupied leading positions to explain the random forest model. They are essential to introduce glucose into the element cycling of the whole community under both treatments. Our work outlines a systematic bacterial response to carbon input.

A high mannose concentration is well tolerated by colorectal adenocarcinoma and melanoma cells but toxic to normal human gingival fibroblast: an in vitro investigation

Background

The primary cause of cancer is gene mutation which allows the growth of abnormal and damaged cells. Nutrition is one of the key factors that either increases or decreases the risk of cancer. Mannose has been found in many fruits such as oranges, apples and berries. Mannose has been linked to increase the risk factors or potential therapeutic for cancers. However, insufficient information is available on the effects of high mannose concentration on the normal and cancer cell lines. This study aimed to evaluate the viability patterns of human cancer and normal cell lines treated with mannose. Human gingival fibroblast (HGF), skin malignant melanoma (A375) and colorectal adenocarcinoma (HT29) cell lines were cultured and treated with additional mannose in three respective concentrations: 1 mg/ml, 5 mg/ml and 10 mg/ml. Then, cell viability was measured using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide)-assay.

Results

The HGF cells’ percentage pattern of viability showed a rapid decline of nearly 95% on the third day of treatment. A375 cells were able to survive in high mannose condition as the cell viability percentage was at the highest value on Day 5. Meanwhile, HT29 cells showed declining cell viability pattern when treated with mannose. The data exhibited significance; the p value was less than 0.001.

Conclusions

High mannose concentration can be toxic to HGF. In addition, A375 is adaptive to mannose at all concentrations in which it shares the same pattern with the untreated group. However, the cell viability pattern for HT29 cell is declining.

The Synthesis of Mannose-6-Phosphate Using Polyphosphate-Dependent Mannose Kinase

Mannose-6-phosphate (M6P) is involved in many metabolic pathways in life, and it has important applications in the treatment of diseases. This study explored a cost-effective enzyme catalytic synthesis method of M6P, using polyphosphate-dependent mannose kinase from Arthrobacter species. This synthesis uses polyphosphate to replace expensive ATP, and it is greener and safer than chemical synthesis. This study investigated the effects of key factors such as metal ions, temperature, and substrate addition on this enzymatic reaction, and improved the conversion efficiency. We moreover take advantage of the response surface method to explore the best catalytic conditions synthetically. The conversion was 99.17% successful under the optimal reaction conditions. After a series of optimizations, we carried out a 200 mL scale-up experiment, which proved that the method has good prospects for industrial applications.