Speciation and antimicrobial resistance of Enterococci isolated from recreational beaches in Malaysia

We report the first study on the occurrence of antibiotic-resistant enterococci in coastal bathing waters in Malaysia. One hundred and sixty-five enterococci isolates recovered from two popular recreational beaches in Malaysia were speciated and screened for antibiotic resistance to a total of eight antibiotics. Prevalence of Enterococcus faecalis and Enterococcus faecium was highest in both beaches. E. faecalis/E. faecium ratio was 0.384:1 and 0.375:1, respectively, for isolates from Port Dickson (PD) and Bagan Lalang (BL). Analysis of Fisher’s exact test showed that association of prevalence of E. faecalis and E. faecium with considered locations was not statistically significant (p?<?0.05). Chi-square test revealed significant differences (χ ²?=?82.630, df?=?20, p?<?0.001) in the frequency of occurrence of enterococci isolates from the considered sites. Resistance was highest to nalidixic acid (94.84 %) and least for chloramphenicol (8.38 %). One-way ANOVA using Tukey–Kramer multiple comparison test showed that resistance to ampicillin was higher in PD beach isolates than BL isolates and the difference was extremely statistically significant (p?<?0.0001). Frequency of occurrence of multiple antibiotic resistance (MAR) isolates were higher for PD beach water (64.29 %) as compared to BL beach water (13.51 %), while MAR indices ranged between 0.198 and 0.48. The results suggest that samples from Port Dickson may contain MAR bacteria and that this could be due to high-risk faecal contamination from sewage discharge pipes that drain into the sea water.     

Assessment of physicochemical parameters of wastewater samples

Water samples from selected locations of Nullah Lai and Koh-e-Noor textile mill in the metropolitan city of Rawalpindi and Islamabad, Pakistan, were collected. Physicochemical parameters and heavy metals were determined using standard analytical procedures in comparison with sites, locations and subsequent interval of 3 months. The results of the physicochemical analysis at different locations of Nullah Lai and Koh-e-Noor textile mill with an interval of 3 months were obtained in the following range: pH (7.16–8.29), temperature (17.8–28.8 °C), conductivity (1,005–3,347 μS/m), TDS (754.3–2,519.5 mg/L), turbidity (272.8–487.05 NTU), total hardness (300–452 mg/L), nitrates (10.11–22.95 ppm), calcium (74.31–139.2 ppm), chloride (127.72–396.16 ppm), sulphate (15.97–87.38 ppm), NaCl (210.5–631.1 ppm), Ni (0.30–0.72 ppm), Cd (0.005–0.03 ppm), Cr (0.2–7.4 ppm), Pb (0.12–0.73 ppm), Zn (0.03–0.08 ppm) and Cu (0.01–0.06 ppm). The highest value of physicochemical parameters (compared with Nullah Lai) was obtained in locations of Koh-e-Noor textile mill. The results obtained exceeded the maximum allowable limit set by the World Health Organization for drinking purpose but can be used for irrigation purposes after suitable treatment and purification.     

Toxicological effects of major environmental pollutants: an overview

The last quarter of the twentieth century had witnessed a global surge in awakening against the unabated menace of environmental pollution. Among the various types of environmental pollution, water pollution is an age-old problem but it has gained an alarming dimension lately because of the problems of population increase, sewage disposal, industrial waste, radioactive waste, etc. Present scenario of water pollution calls for immediate attention towards the remediation and detoxification of these hazardous agents in order to have a healthy living environment. The present communication will deal with the toxicological effects of major environmental pollutants, viz. heavy metals, pesticides, and phenols.     

Cytochrome P450 system as potential biomarkers of certain toxicants: comparison between plant and animal models

In present study, we measured the activities of some selected cytochrome P450 isozymes like ethoxyresorufin-o-deethylase (EROD), pentoxyresorufin-o-deethylase (PROD), and N-nitrosodimethylamine demethylase (NDMA-d) treating experimental rats with different environmental toxicants, namely trichloroethylene (TCE), heavy metal mixture, and ethyl alcohol individually or in combination and by exposing the Allium cepa bulbs to increasing concentration of TCE for 48 h. In animal system, NDMA-d activity displayed a remarkable amplification by 4.2-fold in the liver of alcohol ingested rats compared with control animals. TCE intake also resulted in a marked increase of around 3.8-fold and 1.2-fold in rats’ NDMA-d activity in the liver and kidney, respectively. In onion bulbs, an amazing rise in the activity of test enzymes was recorded in a dose-dependent manner. Among the said enzymes, PROD showed maximum increase up to the extent of 22-fold in comparison with control at 20 ppm of TCE exposure, whereas NDMA-d and EROD showed 11- and 9-fold increase in enzymatic activity, respectively, compared with the control. Based on this study, we conclude and advocate that all the selected isozymes of CYP450 system, viz. PROD, NDMA-d, and EROD can act as potent biomarkers in plant system for assessing the TCE pollution.     

High-level aminoglycoside resistance and virulence characteristics among Enterococci isolated from recreational beaches in Malaysia

We report the first study on the occurrence of high-level aminoglycoside-resistant (HLAR) Enterococci in coastal bathing waters and beach sand in Malaysia. None of the encountered isolates were resistant to high levels of gentamicin (500 μg/mL). However, high-level resistance to kanamycin (2,000 μg/mL) was observed in 14.2 % of tested isolates, the highest proportions observed being among beach sand isolates. High-level resistance to kanamycin was higher among Enterococcus faecalis and Enterococcus faecium than Enterococcus spp. Chi-square analysis showed no significant association between responses to tested antibiotics and the species allocation or source of isolation of all tested Enterococci. The species classification of encountered Enterococci resistance to vancomycin was highest among Enterococcus spp. (5.89 %) followed by E. faecium (4.785) and least among E. faecalis. A total of 160 isolates were also tested for virulence characteristics. On the whole, caseinase production was profoundly highest (15.01 %) while the least prevalent virulence characteristic observed among tested beach Enterococci was haemolysis of rabbit blood (3.65 %). A strong association was observed between the source of isolation and responses for each of caseinase (C?=?0.47, V?=?0.53) and slime (C?=?0.50, V?=?0.58) assays. Analysis of obtained spearman’s coefficient showed a strong correlation between caseinase and each of the slime production (p?=?0.04), gelatinase (p?=?0.0035) and haemolytic activity on horse blood (p?=?0.004), respectively. Suggestively, these are the main virulent characteristics of the studied beach Enterococci. Our findings suggest that recreational beaches may contribute to the dissemination of Enterococci with HLAR and virulence characteristics.     

Spatial variation of potentially toxic elements in different grain size fractions of marine sediments from Gulf of Mannar, India

Marine sediments of the Gulf of Mannar (GoM), India are contaminated by potential toxic elements (PTEs) due to anthropogenic activities posing a risk to the existing fragile coral ecosystem and human health. The current study aimed to assess the distribution of PTEs (arsenic—As; cobalt—Co; copper—Cu, molybdenum—Mo; lead—Pb; and zinc—Zn) in marine sediments of different grain size fractions, viz., medium sand (710 μm), fine sand (250 μm), and clay (<63 μm) among the different coastal regions of Pamban, Palk Bay, and Rameswaram coasts of GoM, using grain size as one of the key factor controlling their concentrations. The concentrations of PTEs were measured in the different size fractions of sediment using inductively coupled plasma mass spectrophotometer. The order of accumulation of all PTEs in the three fractions was ranked as Zn > Cu > Pb > As > Co > Mo and in the three locations as Rameswaram > Palk Bay > Pamban. The concentration of PTEs in Palk Bay and Rameswaram coast was significantly different (P?<?0.05), when compared to Pamban coast. Measured geoaccumulation index (I _geo) and contamination factor (CF) indicated significant enrichment of Co and Pb from Rameswaram coast when compared to other two coasts. Although the concentration of Co was low but the measured I _geo and CF values indicated significant enrichment of this PTE in Rameswaram coast. The increased input of PTEs in the coastal regions of GoM signifies the need to monitor the coast regularly using suitable monitoring tools such as sediments to prevent further damage to the marine ecosystem.     

Modelling and optimisation for design of hydrogen networks for multi-period operation

Hydrogen management is a problem of increasing importance: hydrogen consumption of refineries is rising sharply with additional capacities of hydrocracking and hydrotreating units in order to comply with cleaner fuel specifications. Product Specifications for transportation fuels are becoming increasingly stringent to ensure production of environmentally more benign fuels. Hydrogen management techniques currently do not account for varying operating conditions of hydrogen consuming processes and assume constant operating conditions. A novel approach is developed for the design of flexible hydrogen networks that can remain optimally operable under multiple periods of operation. The proposed methodology for multi-period design of hydrogen networks can take into account pressure differences, maximum capacity of existing equipment, and optimal placement of new equipment such as compressors.     

Multi-metal resistance and plant growth promotion potential of a wastewater bacterium Pseudomonas aeruginosa and its synergistic benefits

Water and soil pollution by toxic heavy metals (HMs) is increasing globally because of increase in population, industrialization and urbanization. It is a burning problem for the public, scientists, academicians and politicians how to tackle the toxic contaminants which jeopardize the environment. One possible solution for pollution abatement is a bioremediation-effective and innovative technology that uses biological systems for treatment of contaminants. Many bacteria synthesize indole-3-acetic acid (IAA) which is a product of l-tryptophan metabolism and belongs to the auxin class of plant growth-promoting hormone. The present study aimed at assessing the resistance pattern of wastewater bacteria against multiple HMs and plant growth promotion activity associated with IAA. A Gram-negative bacterial strain Pseudomonas aeruginosa KUJM was isolated from Kalyani Sewage Treatment Plant. This strain showed the potential to tolerate multiple contaminations such as As(III) (50 mM), As(V) (800 mM), Cd (8 mM), Co (18 mM), Cu (7 mM), Cr (2.5 mM), Ni (3 mM) and Zn (14 mM). The capability of IAA production at different tryptophan concentration (1, 2, 5 and 10 mg mL⁻¹) was determined, and seed germination-enhancing potential was also estimated on lentil (Lens culinaris). Such type of HM-resistant, IAA-producing and seed germination-enhancing P. aeruginosa KUJM offer great promise as inoculants to promote plant growth in the presence of toxic HMs, as well as plant inoculant systems useful for phytoremediation of polluted soils. Hence, P. aeruginosa KUJM finds significant applications in HM-contaminated poor agricultural field as well as in bioremediation of HM-contaminated wastewater system.

     

Removing ammonia from air with a constant pH,slightly acidic water spray wet scrubber using recycled scrubbing solution

Slightly acidic solutions are a practical means of removing ammonia from air Scrubbed NH₃ accumulates in solution as NH₄⁺ and should be an excellent fertilizer Increased air velocity decreased NH₃ removal and increased NH₄⁺ collection Previous research on wet scrubbers has only studied highly acidic scrubbing solutions because of their high ammonia capture efficiencies; however, the high acidity created practical problems. Lower acidity solutions would reduce corrosion, maintenance, and cost; however, designers may need to use strategies for increasing scrubber effectiveness, such as using lower air velocities. The objective of this study was to determine if a spray scrubber with slightly acidic and higher pH scrubbing solution (pH from 2 to 8) could effectively remove NH₃ from NH₃ laden air (such as animal building exhaust air), and also collect this valuable resource for later use as a fertilizer. A bench-scale spray wet scrubber treated 20 ppmv NH₃/air mixture in a countercurrent contact chamber. First, the solution pH was varied from 2 to 8 while maintaining constant air velocity at 1.3 m·s⁻¹. Next, air velocity was increased (2 and 3 m·s⁻¹) while solution pH remained constant at pH6. At 1.3 m·s⁻¹, NH₃ removal efficiencies ranged between 49.0% (pH8) and 84.3% (pH2). This study has shown that slightly acidic scrubbing solutions are a practical means of removing ammonia from air especially if the scrubber is designed to increase collisions between solution droplets and NH₃ molecules. The NH₃ removed from the air was held in solution as NH₄⁺ and accumulates over time so the solution should be an excellent fertilizer.     

Clean electrochemical deposition of calcium carbonate to prevent scale formation in cooling water systems

Calcium carbonate (CaCO₃) deposited in water systems leads to scale formation, decreases flow rate, reduces heat transfer and favors microbial proliferation of toxic bacteria such as Legionella. This issue may be solved by electrochemical deposition, without adding toxic chemicals. Therefore, we studied here the deposition of CaCO₃ by electrochemical reduction of oxygen into hydroxide ions with stainless steel and titanium (Ti) working electrodes. Analysis was done using cyclic voltammetry, chronoamperometry, dynamic impedance spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDX) coupled with X-ray diffraction (XRD). Results show that optimal formation of CaCO₃ is done at ?1.2 V with the stainless steel electrode and at ?1.4 V for the Ti electrode. More negative potentials induce the formation of calcite. Using the Ti electrode, we found that aragonite is the major form (82 %), with only one capacitive loop. Using the stainless steel electrode at 1.2 V, we found 47 % of aragonite and 38 % of calcite. Overall, our findings demonstrate the feasibility of the electrochemical deposition of CaCO₃ in cooling water systems, without the addition of any chemical.