The dynamics of attached and free-living bacterial population in tropical coastal waters

2015 ◽  
Vol 66 (8) ◽  
pp. 701 ◽  
Author(s):  
Siew Wen Lee ◽  
Choon Weng Lee ◽  
Chui Wei Bong ◽  
Kumaran Narayanan ◽  
Edmund Ui-Hang Sim
Keyword(s):  
Coastal Waters ◽  
Bacterial Population ◽  
Bacterial Abundance ◽  
Large Fraction ◽  
Free Living ◽  
Water Port ◽  
Eutrophic Water ◽  
Attached Bacteria ◽  
Student’S T ◽  
Student’S T Test

We investigated the dynamics of attached and free-living bacterial abundance over a period of 18 months in tropical coastal waters of Malaysia. We measured the abundance at both oligotrophic coastal water (Port Dickson) and eutrophic estuary (Klang), and hypothesised that attached bacteria are predominant in eutrophic waters. We found that bacterial abundance was higher at Klang than Port Dickson (Student’s t-test: t=4.87, d.f.=19, P<0.001). Attached bacteria also formed a large fraction of the total bacteria at Klang (75% ±13s.d.) relative to Port Dickson (56% ±22), and showed preference for chlorophyll-a-based particles rather than total suspended solids. The bacterial community structure was clearly different between the two stations but was similar between the attached and free-living bacterial population. Our results showed the importance of attached bacteria in eutrophic water where they could play a major role in carbon and nutrient cycling.

scholarly journals Antagonistic Interactions among Marine Pelagic Bacteria

2001 ◽  
Vol 67 (11) ◽  
pp. 4975-4983 ◽  
Author(s):  
Richard A. Long ◽  
Farooq Azam
Keyword(s):  
Bacterial Abundance ◽  
Antagonistic Activity ◽  
Small Scale ◽  
Free Living ◽  
Associated Bacteria ◽  
Inhibition Of Growth ◽  
Attached Bacteria ◽  
Diffusion Assay ◽  
Antagonistic Interactions

ABSTRACT Recent studies suggest that bacterial abundance and species diversity in the ocean's water column are variable at the millimeter scale, apparently in response to the small-scale heterogeneity in the distribution of organic matter. We hypothesized that bacterium-bacterium antagonistic interactions may contribute to variations in community structure at the microscale. We examined each of the 86 isolates for their inhibition of growth of the remaining 85 isolates by the Burkholder agar diffusion assay. More than one-half of the isolates expressed antagonistic activity, and this trait was more common with particle-associated bacteria than with free-living bacteria. This was exemplified by members of the α subclass of the class Proteobacteria (α-proteobacteria), in which production of antagonistic molecules was dominated by attached bacteria. We found that γ-proteobacteria (members of the ordersAlteromonadales and Vibrionales) are the most prolific producers of inhibitory materials and also the most resilient to them, while members of the Bacteriodetes were the organisms that were least productive and most sensitive to antagonistic interactions. Widespread interspecies growth inhibition is consistent with the role of this phenomenon in structuring bacterial communities at the microscale. Furthermore, our results suggest that bacteria from pelagic marine particles may be an underutilized source of novel antibiotics.

Limnoithona sinensis as refuge for bacteria: protection from UV radiation and chlorine disinfection in drinking water treatment

2014 ◽  
Vol 60 (11) ◽  
pp. 745-752 ◽  
Author(s):  
Tao Lin ◽  
Bo Cai ◽  
Wei Chen
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Uv Radiation ◽  
Bacterial Population ◽  
Drinking Water Treatment ◽  
Free Living ◽  
Surrounding Water ◽  
Chlorine Disinfection ◽  
Attached Bacteria ◽  
Living Bacteria

In this study, we tested the potential of Limnoithona sinensis to provide its attached bacteria refuge against disinfection. The experimental results indicated that in water devoid of zooplankton, both UV radiation and chlorine disinfection significantly decreased the viability of free-living bacteria. In the presence of L. sinensis, however, the attached bacteria could survive and rapidly recover from disinfection. This demonstrated that L. sinensis provided protection from external damage to various aquatic bacteria that were attached to its body. The surviving bacteria remained on L. sinensis after disinfection exposure, which enabled a rapid increase in the bacterial population followed by their subsequent release into the surrounding water. Compared with UV radiation, chlorine disinfection was more effective in terms of inactivating attached bacteria. Both UV radiation and chlorine disinfection had little effect in terms of preventing the spread of undesirable bacteria, due to the incomplete inactivation of the bacteria associated with L. sinensis.

scholarly journals Transcriptome Analysis of Durusdinium Associated with the Transition from Free-Living to Symbiotic

2021 ◽  
Vol 9 (8) ◽  
pp. 1560
Author(s):  
Ikuko Yuyama ◽  
Naoto Ugawa ◽  
Tetsuo Hashimoto
Keyword(s):  
High Stress ◽  
Free Living ◽  
False Discovery Rates ◽  
False Discovery ◽  
Expression Of Genes ◽  
Photosynthesis Genes ◽  
Student’S T ◽  
Shock Proteins ◽  
Related Proteins ◽  
Student’S T Test

To detect the change during coral–dinoflagellate endosymbiosis establishment, we compared transcriptome data derived from free-living and symbiotic Durusdinium, a coral symbiont genus. We detected differentially expressed genes (DEGs) using two statistical methods (edgeR using raw read data and the Student’s t-test using bootstrap resampling read data) and detected 1214 DEGs between the symbiotic and free-living states, which we subjected to gene ontology (GO) analysis. Based on the representative GO terms and 50 DEGs with low false discovery rates, changes in Durusdinium during endosymbiosis were predicted. The expression of genes related to heat-shock proteins and microtubule-related proteins tended to decrease, and those of photosynthesis genes tended to increase. In addition, a phylogenetic analysis of dapdiamide A (antibiotics) synthase, which was upregulated among the 50 DEGs, confirmed that two genera in the Symbiodiniaceae family, Durusdinium and Symbiodinium, retain dapdiamide A synthase. This antibiotic synthase-related gene may contribute to the high stress tolerance documented in Durusdinium species, and its increased expression during endosymbiosis suggests increased antibacterial activity within the symbiotic complex.

Iron effects on colonization behavior, motility, and enzymatic activity of marine bacteria

2007 ◽  
Vol 53 (8) ◽  
pp. 968-974 ◽  
Author(s):  
Kam W. Tang ◽  
Hans-Peter Grossart
Keyword(s):  
Marine Bacteria ◽  
Laboratory Experiments ◽  
Large Fraction ◽  
Iron Limitation ◽  
Colonization Rate ◽  
Particle Interactions ◽  
Iron Availability ◽  
Free Living ◽  
Attached Bacteria ◽  
Colonization Behavior

Iron availability in the ocean has been shown to affect the growth and production of phytoplankton and free-living bacteria. A large fraction of marine bacteria are specialized in colonizing and living on particles and aggregates, but the effects of iron limitation on these bacteria are not fully known. We conducted laboratory experiments to study the effects of iron availability on particle colonization behavior, motility, and enzymatic activities of 4 strains of marine bacteria. Iron depletion reduced the bacterial particle colonization rate by 1.7%–43.1%, which could be attributed to reduced swimming speeds in 2 of the 4 strains. Protease activity was not affected by iron availability. However, attached bacteria did show higher protease activities than their free counterparts. Our results suggest that iron limitation in the ocean could in some cases reduce bacteria–particle interactions by reducing bacterial motility and colonization rate.

Serosal and cutaneous recordings of gastric myoelectrical activity in patients with gastroparesis

1994 ◽  
Vol 266 (1) ◽  
pp. G90-G98 ◽  
Author(s):  
J. D. Chen ◽  
B. D. Schirmer ◽  
R. W. McCallum
Keyword(s):  
Electrical Stimulation ◽  
Slow Wave ◽  
Test Meal ◽  
Frequency Change ◽  
Fasting State ◽  
Gastric Myoelectrical Activity ◽  
Myoelectrical Activity ◽  
Gastric Slow Wave ◽  
Student’S T ◽  
Student’S T Test

The aims of this study were to 1) investigate gastric myoelectrical activity in patients with gastroparesis, 2) validate the cutaneous electrogastrogram (EGG) in tracking the frequency change of the gastric slow wave, and 3) investigate the effect of electrical stimulation on gastric myoelectrical activity. Gastric myoelectrical activity was recorded in 12 patients with documented gastroparesis using serosal electrodes for > 200 min in each subject. All recordings were made at least 4 days after surgery. Each session consisted of a 30-min recording in the fasting state and a 30-min recording after a test meal. The test meal (liquid or mixed) was selected according to patient's tolerance. Electrical stimulation was performed in three subjects via the serosal electrodes at a frequency of 3 cycles/min. Gastric myoelectrical activity was recorded using serosal electrodes in each session. The serosal recording showed slow waves of 2.5 to 4.0 cycles/min in all 12 subjects. Absence of spikes was noted in 11 of the 12 subjects. The simultaneous serosal and cutaneous recording of gastric myoelectrical activity showed that the frequency of the EGG was exactly the same as that of the serosal recording. Liquid meals resulted in a significant decrease in slow-wave frequency (Student's t test, P = 0.006), and the EGG accurately reflected this change. Electrical stimulation had no effect on the frequency of the gastric slow wave and did not induce spikes.(ABSTRACT TRUNCATED AT 250 WORDS)

The Effect of Changes in Dialysate Volume on Glucose and Urea Equilibration

1994 ◽  
Vol 14 (3) ◽  
pp. 236-239 ◽  
Author(s):  
Edward C. Kohaut ◽  
F. Bryson Waldo ◽  
Mark R. Benfield
Keyword(s):  
Renal Failure ◽  
Chronic Renal Failure ◽  
Prospective Study ◽  
Body Surface ◽  
Patient Population ◽  
Different Ages ◽  
Student’S T ◽  
A Prospective Study ◽  
Dialysate Volume ◽  
Student’S T Test

Objectives To determine the effect of changing dialysate volume on urea and glucoseequilibration curves and to determine, if dialysate volume is prescribed on the basis of body surface area, whether equilibration curves will be consistent in patients of different sizes and ages. Design A prospective study wherein children with acute or chronic renal failure had peritoneal equilibration studies done with dwell volumes of 30 mL/kg, 40 mL/kg, and 1200 mL/m2. Patient Population Twenty-two children: 7 under 3 years of age; 8 between 3 and 10 years of age; 7 older than 10 years of age. Statistics Student's t-test. Results Urea and glucose equilibrated rapidly at dwell volumes of 30 mL/kg, slower at dwell volumes of 40 mL/kg, and slowest at dwell volumes of 1200 mL/m2. Equilibration curves were similar in children of different ages when dialysate volumes of 1200 mL/m2 were infused. Conclusion Dialysate volumes of 1200 mL/m2 should be used when equilibration studies are being done to compare individuals of different ages and sizes.

scholarly journals Development and Validation of 2-Azaspiro [4,5] Decan-3-One (Impurity A) in Gabapentin Determination Method Using qNMR Spectroscopy

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1656
Author(s):  
Nataliya E. Kuz’mina ◽  
Sergey V. Moiseev ◽  
Mikhail D. Khorolskiy ◽  
Anna I. Lutceva
Keyword(s):  
Test Procedure ◽  
Active Pharmaceutical Ingredient ◽  
Test Methods ◽  
Intermediate Precision ◽  
Coefficients Of Variation ◽  
Validation Parameters ◽  
Limit Of Quantitation ◽  
Student’S T ◽  
Development And Validation ◽  
Student’S T Test

The authors developed a 1H qNMR test procedure for identification and quantification of impurity A present in gabapentin active pharmaceutical ingredient (API) and gabapentin products. The validation studies helped to determine the limit of quantitation and assess linearity, accuracy, repeatability, intermediate precision, specificity, and robustness of the procedure. Spike-and-recovery assays were used to calculate standard deviations, coefficients of variation, confidence intervals, bias, Fisher’s F test, and Student’s t-test for assay results. The obtained statistical values satisfy the acceptance criteria for the validation parameters. The authors compared the results of impurity A quantification in gabapentin APIs and capsules by using the 1H qNMR and HPLC test methods.

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