Total Bacterial Growth Research Articles

Enrichment and Characterization of Sheep Caecum Mixed Lactic Acid Bacteria as Potential Direct-fed Microbials (DFMs) in Livestock

Abstract Lactic Acid Bacteria (LAB) have been widely used as feed supplements in the form of live bacteria or Direct-fed microbials (DFMs) which are expected to have a positive impact on livestock productivity. However, each LAB strain has different characteristics so its ability to influence its host livestock will also be different. This research aims to characterize the LAB enrichment process obtained from the caecum of sheep. The sheep caecum LAB underwent re-inoculated while being enriched in MRS broth medium. After obtaining the LAB isolates, characterization was carried out in the form of pH measurements, total plate count, bacteriocin production, and bacterial kinetic growth. The results showed that LAB could be grown from the digesta of sheep caecum as seen from the decrease in the average pH of the growth medium reaching pH 4.14 with a bacterial colony count of 6,01 log CFU/ml. The grown LAB had a Ks value of 0.24 μM glucose and a μmax value of 2.69 OD. Apart from that, the clear zone test showed a positive result. In conclusion, Enrichment of mixed LAB cultures from sheep caecum has decreased environmental pH by 33%. Sheep caecum mixed LAB culture has easy growth characteristics and antimicrobial activity so it can be a suitable alternative DMF candidate. Further research focusing on the application of this LAB strain is needed to be able to determine the effect of bacteria on livestock.

To Isolate and Identify the Etiological Agents and Establish the Co-Relation between Pyuria and Significant Bacteriuria among Patients Suspected of Urinary Tract Infection

Urinary tract infection (UTI) one of the most common infectious diseases has been seen as a global burden. Escherichia coli (E. coli) is responsible for causing majority of the UTIs. This study was conducted at Kantipur Hospital Pvt. Ltd. Kathmandu from July 2016 to December 2017.The research was conducted to study about the relation between pyuria and bacteriuria among patients suspected of urinary tract infection. A total of 464 mid-stream urine samples were collected. Out of total processed sample 97/464 was positive while 263 were culturally negative. E. coli accounted for 76.28 %( 74) of the growth while K. pneumoniae accounted for 9.27% (9) of the total bacterial growth. Other organism which were found were P. vulgaris 8.24 (8) S. aureus 3.09 %( 3), Coagulase negative staphylococcus (CoNS) 1.03% (1), E. facealis1.03% (1) and P. aeruginosa 1.03% (1). Amikacin was most susceptible drugs for E. coli with 90.54% (67) success followed by gentamicin 81.08 %( 60). Both amikacin and gentamicin proved susceptible for other gram negative isolates too. Among the total isolates 73 of them were found to Multi Drug Resistant (MDR) were E. coli 92.85% (66) has most number of MDR cases followed by 3.96 %( 4).It was found that female patient were more affected (79) than male patient (18).While on age group basis people aging between 21-30 years mostly had infection (31). Among the 464 samples, 78.67% (365) of samples showed insignificant pyuria. However, 4.12% of samples gave positive culture results. The highest Culture positivity, 28 (75.67%) samples out of 37 was detected in urine samples having pus cells of 6-10/hpf, whereas 5(33.33%) urine samples with more han 50 pus cells/hpf was culture positive. Female are more susceptible for UTI than Male and presence of pyuria can be good indicator of urine infection, though Culture should always be considered as gold standard.

Optimization and Analysis of Polyhydroxyalkanoate (PHA) by Bacillus sp. Strain CL33 and Bacillus flexus Strain S5a from Palm Oil Mill Waste

Polyhydroxyalkanoate (PHA) is a biodegradable polymer that microorganisms can synthesize amidst non-optimal growth conditions with excess carbon sources. Palm oil, rich in fatty acids, serves as a carbon source for PHA synthesis. The bacterial PHA production can be influenced by carbon concentration in the growth medium. Therefore, determining the optimal concentration of palm oil as a carbon source is crucial for PHA production. Additionally, it is possible to determine the type of PHA generated by bacteria, which can then be utilized as information when processing utilizing the PHA. The experiment employed palm oil concentrations of 0.5%, 1%, and 2% and was carried out for periods of 48, 72, 96 hours. It was discovered that Bacillus sp. strain CL33 and Bacillus flexus strain S5a produced the most effective PHA at a concentration of 25 with an incubation period of 96 hours. The PHA generated by these bacteria was quantitatively analyzed through measurements of total bacterial growth, cell dry weight, and the levels of crotonic acid. PHA types were also analyzed using GC-MS, with monomers including 2-hydroxybutyrate(-2HB), 2-hydroxy-3-phenylpropionate (2H3PhP), 3-Hydroxyhexanoate (3HHx), 3-hydroxyoctanoate (3H2O), and 3-hydroxydecanoate (3HD). The Bacillus sp. strain CL33 yielded a PHA level of 92.23%. Meanwhile, Bacillus flexus strain S5a synthesized a polyhydroxyalkanoate comprising mostly 3-hydroxyhexanoate (3HHx) and polydimethylsiloxane (PDMS). The monomers used were decamethyltetrasiloxane, dodecamethylpentasiloxane, hexamethylcyclotrisiloxane, octamethylpentasiloxane, and dodecamethylcyclohexasiloxane. The type of PHA produced accounted for 85.93% of the total.

Ultrasonic synergistic slightly acidic electrolyzed water processing to improve postharvest storage quality of Chinese bayberry

In the postharvest storage of Chinese bayberry, microbial loads and exogenous contaminants pose significant challenges, leading to rapid decay and deterioration in quality. This study introduced a synergistic approach, combining ultrasonics and slightly acidic electrolyzed water (US + SAEW), to enhance the postharvest storage quality of Chinese bayberry. This approach was benchmarked against conventional water washing (CW), standalone ultrasonic (US), and slightly acidic electrolyzed water (SAEW) processing. Notably, compared to CW, the US + SAEW method enhanced iprodione and procymidone removal rates by 69.62 % and 72.45 % respectively, improved dirt removal efficiency by 122.87 %, repelled drosophila melanogaster larvae by 58.33 %, and curtailed total bacterial, mold & yeast growth by 78.18 % and 83.09 %. Furthermore, it postponed the appearance of sample decay by 6 days, compared to 4 days for both US and SAEW alone. From a physicochemical perspective, compared to CW-treated samples, US + SAEW processing mitigated weight loss and color deviations, retained hardness, amplified the sugar-acid ratio, augmented activities of phenylalanine ammonia-lyase, superoxide dismutase, and catalase enzymes, suppressed polyphenol oxidase activity and malondialdehyde synthesis, and preserved total phenolic, anthocyanin, and antioxidant levels. These findings underscore the potential of US + SAEW as a strategic tool to preserve the quality of Chinese bayberry during postharvest storage.

Smart bactericide based on reduced graphene oxide decorated with copper and zinc nanoparticles

Graphene oxide (GO) synthesised by modified Tour’s method was decorated with copper and zinc nanoparticles (NPs) and simultaneously reduced by sodium borohydride to obtain a nanocomposite of reduced GO with copper and zinc NPs (rGO–Cu–Zn). The nanocomposite rGO–Cu–Zn was characterised by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The rGO–Cu–Zn was tested against Xanthomonas euvesicatoria (X. euvesicatoria), which attacks tomatoes and causes bacterial spots (BSs), and compared with the commercial product Champion 50 WG. Total bacterial growth inhibition was observed for the 1% rGO–Cu–Zn, whereas Champion 50 WG at the same concentration inhibited but did not eradicate all the bacterial colonies. To evaluate the negative effect of the rGO–Cu–Zn on the molecular level, the expression of the genes associated with the action of abiotic and biotic stress factors was analysed. Gene expression in the plants treated with 10% rGO–Cu–Zn did not exhibit a noticeable increase.Graphical

Using of Modern Genetic Methods to Detect Air-Borne Bacterial Genes Through Desert Storms in Iraq

Abstract Antibiotic resistance of pathogens is a serious issue that affects health. The airborne particle molecules such as (PM2.5, PM10) that spread by dust storms can increase the antibiotic resistance in bacterial community. In this study air samples of the dust storms were collected and the air-borne bacteria were cultured on specific growth media by portable air sampler device (SAS). Sixty plates were used through the atmospheric storms dust which included three periods of 24/5/2022,13/6/2022 and 3/7/2022. Antibiotic resistance of bacterial isolates was detected by VITEK2. Bacterial whole DNA was extracted and the genes against the most resisted antibiotics were detected by specific pre-designed primers and by using gel electrophoresis method. The results showed homogenous high concentrations of both PM2.5 and PM10 were included in storm samples just like that in Saudi Arabia. The greatest numbers of bacterial growth in collecting plates through the storm included 45 of 60 (75%) E. coli, 36 of 60 (60%) of Staphylococcus epidermis and 15 of 60 (25%) of Sphingomonas paucimobilis isolates of total bacterial growth as diagnosed by morphological characteristics and VITEK2 system. The antibiotic sensitivity test (AST) which was done by VITIK2 showed multidrug resistant for Staphylococcus epidermis, E. coli and Sphingomonas paucimobilis strains, mainly against erythromycin and tertacycline. The results of genetic studies for the antibiotic resistance illustrated the presence of gene fragments of both ermA gene and tetK gene within the bacterial nucleic acid, which are considered as potent antibiotic resistance genes (ARGs genes). In conclusion, the resistance of air-borne bacteria towards used antibiotics were elevated strongly in relation with the expression of ARGs associated with the huge amounts of PM particles in dust storms that occurred in Iraq, which is very harmful for human and other living forms on earth.

Healthy adult gut microbiota sustains its own vitamin B12 requirement in an in vitro batch fermentation model.

Vitamin B12 (cobalamin) is present in the human lower gastrointestinal tract either coming from the unabsorbed dietary fraction or from in situ production of the gut microbiota. However, it is unclear whether the gut microbial communities need exogenous B12 for growth and metabolism, or whether B12 in low and high levels could affect gut community composition and metabolite production. Here, we investigated in vitro B12 production of human fecal microbiota and the effects of different levels of B12 (as cyanocobalamin) on composition and activity. Eight fecal communities from healthy human adults distributed over three enterotypes, dominated by Firmicutes (n = 5), Bacteroides (n = 1) or Prevotella (n = 2) were used to perform batch fermentations in Macfarlane medium supplemented with low B12 medium (Control, 5 ng/ml, within the tested fecal range), no B12 addition (NB12), and high B12 addition (ExtraB12, 2500 ng/ml). The microbiota community composition (qPCR, 16S rRNA metabarcoding), metabolic activity (HPLC-RI), and B12 levels (UHPLC-DAD) were measured after 24 h incubation at 37°C under strict anaerobic conditions. All fecal microbial communities produced B12 in the NB12 condition after 24 h, in the range from 152 ± 4 to 564 ± 25 ng/ml. None of the B12 treatments had an impact on total bacterial growth, community richness, diversity and total metabolite production, compared to the low B12 control. However, a significant increase of propionate was measured in ExtraB12 compared to NB12. Most taxonomic and metabolite changes compared to control incubations were donor-dependent, implying donor-microbiota-specific changes upon B12 treatments. Our in vitro data suggest that healthy human adult gut microbial communities have the capacity to produce B12 at levels fulfilling their own requirements, independently of the initial B12 content tested in the donor's feces. Further, supplementation of exogenous dietary B12 may have limited impact on the healthy human gut microbial community composition and function.

Molecular screening of RND-type efflux pumps genes among Pseudomonas aeruginosa isolated from burn patients in Najaf City, Iraq

Pseudomonas aeruginosa (P. aeruginosa) is a main clinical opportunistic pathogen that causes of morbidity and mortality among burn patients. therefore this study aimed to detection of RND-type efflux pump genes among P. aeruginosa isolates in Najaf City, using PCR technique. The study involved 68 specimen's obtained from burn patients visited burns unit center as well as some chief clinical laboratories in Najaf City period December 2021 to March 2022. This study showed among 68 burn patients 47(69.11%) and 12 (17.64%) of positive bacterial growth returned to gram-negative and gram-positive bacteria respectively. In contrast, 9(13.23%) of specimens were no growth. In the same respect, the results according to total positive bacterial growth have shown that the rate of P. aeruginosa isolates was 32(54.23%) At same as following 12(20.33%) in men compared with 20(33.89%) in women. The molecular results of efflux pump genes in this study revealed that 31 (96.87%%) of P. aeruginosa isolates were contained MexA and MexD genes, While 30(93.75%) of isolates were positive for MexB gene. Moreover, 25(78.12%) of isolates were harbored MexC and MexY genes, as well as 23(71.87%) of isolates were harbored MexX gene.

The Effect of Sloping the Grinder Body of the Meat-Mincer Machines on the Reduction of Microorganism and Chemical Residuals after Cleaning-A Newly Design

Hygiene is critical for human health, particularly in locations where industrial meat products are produced. One of the most common causes of contamination in the meat sector is meat grinders, which are notoriously difficult to clean. As a result, eliminating the water that has accumulated in the body is critical for the meat grinders' hygiene. In the presented study the effect of tilting the neck region after grinder body washing on total bacterial growth, pH, and pathogens in a meat grinder functioning regularly in a workplace was investigated. The machine was cleaned, then set to the predetermined angle value and the sample was taken 5 minutes later. The machine was maintained at this angle value for 15 hours, then swab was taken before the morning began. swab samples were taken after cleaning and pre-production at 0, 10, 20, 30, and 40 degrees slopes. When the results were combined, it was discovered that about 30% decrease in the overall number of bacteria was observed with a 30-degree tilt. Since there is no antigen in the neck region after the cleaning, there is no salmonella and Listeria monocytogenes. The pH level approached that of the cleaning water, eliminating the cleaning chemicals' impact.

Effect of a Tea Polyphenol on Different Levels of Exposure of Nicotine and Tobacco Extract on Streptococcus mutans Biofilm Formation.

Objective: The purpose of this study was to compare the effects of different levels of nicotine and tobacco extract exposure on Streptococcus mutans biofilm formation and the inhibitory effect of the polyphenol epigallocatechin-3 gallate (EGCG) found in green tea. This study addressed the results of biofilm assays with EGCG and varying relative concentrations of nicotine and tobacco extract consistent with primary, secondary and tertiary levels of smoking exposure. Primary smoking exposure to nicotine has been demonstrated to significantly increase biofilm formation, while EGCG has been demonstrated to reduce S. mutans biofilm formation.Methods: S. mutans was treated with varying levels of nicotine or cigarette smoke condensate (CSC) concentrations (0–32 mg/ml and 0–2 mg/ml, respectively) in Tryptic Soy broth supplemented with 1% sucrose for different lengths of time simulating primary, secondary and tertiary smoking exposure with and without 0.25 mg/ml EGCG. The amount of total growth and biofilm formed was determined using a spectrophotometric crystal violet dye staining assay.Results: For both nicotine and CSC, primary exposure displayed overall significantly less growth compared to secondary exposure. For nicotine, secondary exposure demonstrated significantly greater growth than tertiary exposure levels. Overall, significantly greater total bacterial growth and biofilm formation in the presence of nicotine and CSC was observed in the absence of EGCG than in the presence of EGCG. However, biofilm growth was not significantly different among different concentrations of CSC.Conclusion: The results of this study help illustrate that nicotine-induced S. mutans biofilm formation is reduced by the presence of EGCG. This provides further evidence of the potential beneficial properties of polyphenols.

Treatment of compost as a source of organic material for bacterial consortium in the removal of sulfate and heavy metal lead (Pb) from acid mine drainage

Acid mine drainage can pollute the environment because it is acidic and contains toxic heavy metals. The purpose of this research was the application of a bacterial consortium to remove sulfate and reduce heavy metal lead (Pb) in acid mine drainage. The application was done in the bioreactor for acid mine drainage treatment that was treated with compost. Observations were made every five days and included observation of total bacterial growth using the Standard Plate Count (SPC) method, determination of sulfate content by gravimetry, determination of pH by use of pH meter, and determination of the concentration of heavy metal Pb using the AAS method. As a result, it was obtained that the treatment of non-sterile compost in acid mine drainage was able to reduce the initial heavy metal concentration of Pb of 84% and reduce the sulfate content by 72%, along with increasing pH and an increase in total bacterial growth. Meanwhile, sterile compost treatment was only able to reduce the Pb content by 63% and sulfate by 54%. This result indicates that the addition of compost is more effective than the treatment of sterile compost.

Effect of Fermentation Time on The Dynamics of Lactobacillus plantarum Bacteria using Collagen Extract from Broiler Claw Skin as a Substrate

Research has been carried out to evaluate the growth dynamics of lactic acid bacteria (LAB) Lactobacillus plantarum (L.plantarum) using collagen extract (CE) from the broiler claw skin (BCS) as a substrate. The bacterial dynamics studied were related to total lactic acid (TLA) production, pH, dissolved protein (DP) and bacterial growth (BG) during the fermentation process. A total of 50 g of BCS was used with fermentation time (24; 48 and 72 hours). The results was showed that fermentation time using L.plantarum as a culture with CE from BCS as a substrate did not affect on bacterial dynamics (TLA, pH, dissolved protein and BG) during the fermentation process. Using L.plantarum with EC from BCS as substrate can be applied with 24 hours fermentation time. The bacterial dynamics produced by the fermentation time were 2.35±0.50%; 5.88±0.10; 45.60±2.21 mg/mL and 15.591±0.92 Log10 CFU/mL respectively.

Level Pemberian Tepung Rosella (Hibiscus sabdariffa Linn) Terhadap Kualitas Dendeng Babi

The purpose of this research to determine the level on the quality of pork jerky (aroma, texture and TPC). The research design used was a complete random design (CRD) with 4 treatments and 3 replications, and continued with Mann-Whitney test. The sensoric data used hedonik test according to Kruskal-Wallis method. The treatment consisted of R0 = without roselle flour, R1 = roselle flour 5g, R2 = roselle flour 10g and R3 = roselle flour 15g. The results showed that the addition of roselle flour 5g, 10g and 15g gave a significant difference (P <0.05) to the aroma and TPC values while the texture had no significant effect (P>0,05). But the best texture value is at the level of 10g roselle flour. Conclusion, The level of roselle flour influences the value of the aroma of jerky and can reduce the total bacterial growth in the pork jerky. The best activity level of 15g roselle flour can reduce the lowest total bacterial colony.

Single DNase or Proteinase Treatment Induces Change in Composition and Structural Integrity of Multispecies Oral Biofilms.

Biofilm virulence is mainly based on its bacterial cell surrounding biofilm matrix, which contains a scaffold of exopolysaccharides, carbohydrates, proteins, lipids, and nucleic acids. Targeting these nucleid acids or proteins could enable an efficient biofilm control. Therefore, the study aimed to test the effect of deoxyribonuclease I (DNase I) and proteinase K on oral biofilms. Six-species biofilms (Streptococcus mutans, Streptococcus oralis, Actinomyces oris, Fusobacterium nucleatum, Veillonella dispar, and Candida albicans) were exposed to DNase I (0.001 mg/mL, 0.002 mg/mL) or proteinase K (0.05 mg/mL, 0.1 mg/mL) for 1 h during biofilm formation. After 64 h, biofilms were harvested, quantified by culture analysis and visualized by image analysis using CLSM (confocal laser scanning microscopy). Statistical analysis was performed by ANOVA, followed by the Tukey test at a 5% significance level. The biofilm treatment with proteinase K induced a significant increase of Logs10 counts in S. mutans and a decrease in C. albicans, while biofilm thickness was reduced from 28.5 μm (control) to 9.07 μm (0.05 mg/mL) and 7.4 μm (0.1 mg/mL). Treatment with DNase I had no effect on the total bacterial growth within the biofilm. Targeting proteins of biofilms by proteinase K are promising adjunctive tool for biofilm control.

Проблемы диагностики и лечения бактериального вагиноза в активном репродуктивном возрасте

Aim: to assess the efficacy and safety of vaginal capsules containing metronidazole 100 mg and myconazole nitrate 100 mg in women with bacterial vaginosis (including recurrent vaginosis). Patients and Methods: 62 women were enrolled. Group 1 included 32 women with firstly diagnosed bacterial vaginosis. Group 2 included 30 women with recurrent bacterial vaginosis. Vaginal capsules containing 100 mg of metronidazole and 100 mg of miconazole nitrate (Gynocaps) or Gynocaps plus peroral metronidazole 250 mg twice daily (combined therapy) were prescribed. Group 1 and group 2 were divided into subgroups, i.e., 1A (n=20) and 1B (n=12), 2A (n=18) and 2B (n=12), based on treatment (monotherapy or combined therapy, respectively). Treatment efficacy was assessed 1 month and 12 months after completing treatment. Results: the major symptom in both groups was off-white vaginal discharge. Diffuse vulvar redness was more common in group 1 while petechiae were more common in group 2 (p<0.05). Lactobacillus spp. counts were reduced in all women, mixed infections were predominant. In group 2, significantly higher counts of anaerobic and yeast flora compared to group 1 were reported (p<0.05). In group 1, no significant differences in the improvement of clinical signs after both treatment regimens were reported. Meanwhile, in group 2, clinical signs improved more rapidly after combined treatment. However, combined treatment was associated with adverse effects. A reduction in the total bacterial mass and logarithmic growth of anaerobic microflora was observed irrespective of the treatment regimen. No recurrences of bacterial vaginosis were reported. Conclusions: a 10-day treatment course of combined vaginal capsules containing metronidazole 100 mg and miconazole nitrate 100 mg improves clinical signs, eliminates complaints, and improves vaginal microflora owing to Lactobacillus growth without adverse reactions. In recurrent vaginosis, this agent should be used in combination with antibiotics. KEYWORDS: bacterial vaginosis, active reproductive age, metronidazole, miconazole nitrate, Lactobacillus. FOR CITATION: Chebotareva Yu.Yu. Diagnosis and treatment of bacterial vaginosis during active reproductive age. Russian Journal of Woman and Child Health. 2021;4(3):218–224 (in Russ.). DOI: 10.32364/2618-8430-2021-4-3-218-224.

Bacteriological quality of commercially prepared fermented Ogi (Akamu) sold in Some Parts of Afikpo Area in Ebonyi State

In this study ogi (akamu) prepared from fermented maize sold in Enohia, Afikpo and Unwana were subjected to bacteriological test together with the laboratory prepared ogi for bacterial quality using the standard microbiological method. The commercial purchased ogi from the markets of (Enohia, Unwana and Afikpo) showed total bacterial growth of 5.6 × 107, 2.0 × 103, 4.2 × 102 and 3.6 × 106 respectively. Staphylococci growth count of 4.2×102, 2.9×102 and 3.5 × 102 were recorded respectively, while Coliform count recorded 2.0×103, 1.2×103 and 1.5×103 and Lactic acid bacterial loads of 3.6×106, 2.7×106 and 3.2 × 106 respectively. The bacteria isolated from the commercial and laboratory fermented pap were Lactobacillus sp, Staphylococcus sp, Leuconostoc sp, Micrococcus sp, Salmonella sp, E. coli, Citrobacter sp and Klebsiella sp. Lactobacillus sp Leuconostoc sp and Citrobacter sp were present in all the samples, Micrococcus sp and Klebsiella sp were isolated from Enohia and Unwana markets ogi respectively, while E. coli and Staphylococcus sp were present in Enohia, Unwana and Afikpo markets. Salmonella sp were isolated from the three markets. No pathogenic bacteria was isolated from the laboratory Prepared ogi (Akamu). Hence, there are chances of contracting food borne diseases from commercially prepared ogi in the local areas of study. Therefore, there is need for sanitary measures in the production of fermented cereals such as ogi so as to minimize the rate of food borne pathogens during processing and storage of such cereals.

Antibacterial and mechanical properties of arginine-containing glass ionomer cements

ObjectiveThe study investigated the effect of incorporating l-arginine (Arg) in a glass ionomer cement (GIC) on its mechanical properties and antibacterial potential. MethodsPre-determined proportions (1%, 2%, and 4% by wt.) of Arg were incorporated in GIC powder; while GIC without Arg served as control. The flexural strength, nanohardness, surface roughness, elemental analysis using SEM-EDX (n = 6) and F/Arg/Ca/Al/Si release in deionized water for 21 days were assessed. The antibacterial potential was evaluated in a multi-species biofilm model with Streptococcus mutans, Streptococcus sanguinis, Streptococcus gordonii, and Lactobacillus acidophilus for 72 h. Real-time qPCR was used to analyse biofilm bacterial concentrations. Propidium monoazide modification of real-time qPCR was performed to quantify viable/dead bacteria. The pH, lactic acid, ADS activity, and H2O2 metabolism were measured. Confocal microscopy was used to investigate the biofilm bacterial live/dead cells, density, and thickness. ResultsThere was no difference in flexural strength among the different groups (p > 0.05). No significant difference in nanohardness and surface roughness was observed between 4% Arg + GIC and control (p > 0.05). The 4% Arg + GIC showed significantly higher F/Arg/Al/Si release than the other groups (p < 0.05), reduced total bacterial concentration and growth inhibition of viable S. mutans and S. sanguinis (p < 0.05). Lactic acid formation for 4% Arg + GIC was significantly higher than 1% Arg + GIC (p < 0.05). The spent media pH of 4% Arg + GIC was higher than the other groups (p < 0.05), with proportionately lower ammonia and higher H2O2 released (p < 0.05). SignificanceAddition of 4% l-arginine in GIC enhanced its antibacterial activity via a biofilm modulatory effect for microbial homeostasis, with no detrimental effect on its mechanical properties.

Multivariate control of heterotrophic bacterial abundance and zooplankton grazing in Labrador fjords (northeastern Canada)

This study was conducted in 4 Labrador fjords (Nachvak, Saglek, Okak, and Anaktalak) during the summers of 2007 and 2013, early fall 2010, and late fall 2009. Our results show that water temperature combined with the availability of nutrients and organic substrates are the main abiotic factors controlling the abundance of heterotrophic bacteria in Labrador fjords. Bacterivory also played a crucial role, with heterotrophic bacteria exerting a significant bottom-up control on the abundance of heterotrophic nanoflagellates (r = 0.35, p &lt; 0.05) and ciliates (r = 0.70, p &lt; 0.01). During summer 2013, the intrinsic phytoplankton growth rate varied between &lt;0 and 0.64 d-1, with a mean value of 0.36 d-1. The herbivory rate was highly variable, ranging from 0.01 to 0.86 d-1, with a mean value of 0.31 d-1. Grazing mortality was 6-fold higher than phytoplankton growth rate. Mean phytoplankton growth and herbivory rates in Labrador fjords were comparable to the Barents and Bering seas. The intrinsic growth rate of total heterotrophic bacteria ranged between &lt;0 and 0.68 d-1, with a mean value of 0.30 d-1. Bacterivory varied from 0.01 to 0.95 d-1, with a mean of 0.30 d-1. Mortality due to grazing was up to 2.3 times higher than total bacterial growth rate. This study improves our understanding of the factors influencing the dynamics of heterotrophic bacteria and indicates that herbivory and bacterivory exert substantial control on microbial communities in Labrador fjords.

Zinc Oxide Inhibits Axillary Colonization by Members of the Genus Corynebacterium and Attenuates Self-perceived Malodour: A Randomized, Double-blind, Placebo-controlled Trial.

Malodour from the axilla is commonly caused by specific microbes, and may be inhibited by zinc oxide. The aim of this study was to determine the effects of zinc oxide on the axillary microbiota, odour and pH in a randomized, double-blind, placebo-controlled trial in 30 healthy volunteers. In each participant one axilla was treated with zinc oxide and the other with a placebo for 13 days. The microbiota and pH were ana-lysed before and during treatment. At the final visit, the participants judged their own axillary odour for comparison. With zinc oxide treatment total bacterial growth and, specifically, that of odour-producing Corynebacterium spp. and Staphylococcus hominis, decreased (p<0.05), despite an increase (p<0.0005) in skin-surface pH. Compared with the placebo, zinc oxide treatment reduced (p = 0.005) self-perceived malodour. In vitro, Corynebacterium spp. (19 isolated strains) survival was reduced (p<0.0005) at pH 5.0 compared with pH 6.0; growth inhibition by zinc oxide occurred at ≤400 mg/l, and cell death occurred at ≤10,000 mg/l for 12 (63%) of the strains. In conclusion, application of zinc oxide reduced malodour and the counts of causative bacteria, but increased the pH of the axilla.

Perspective on desalination discharges and coastal environments of the Arabian Peninsula

Two opposing views are held about the effects of desalination plants on coastal environments. One view is that brine discharged from desalination plants has minimal impact on the coastal environment. The other opinion claims that discharges from desalination plants pose a potential environmental hazard to coastal environments and particularly to those of the Arabian Gulf. The present study was carried out to determine whether negative environmental impacts could be detected in coastal waters of the Gulf and Red Sea near discharges from desalination plants in Saudi Arabia. Phytoplankton abundance, concentrations of chlorophyll a, nutrients, total suspended solids, trace metals, chlorination by-products, bacterial growth, and toxicity of effluents were assessed. Results indicate the brine discharges were not toxic to fish or brine shrimp. Mitigation of impacts from elevated temperature, salinity and chemicals in dual purpose plants is partly achieved by pre-dilution of brine reject stream with cooling water. Alternative pretreatment methods, chlorination and waste treatment are considered. There is accumulation of corrosion metals in sediments at the discharge site of a plant on the Gulf coast. However, their concentrations were within regulatory limits.