Isolation and characterization of hydrocarbon-degrading bacteria from gas station leaking-contaminated groundwater in the Southern Amazon, Brazil.

Twenty-three hydrocarbon-degrading bacteria strains were isolated from gas station leaking-contaminated groundwater located in the Southern Amazon, Brazil. Based on hydrocarbon (diesel, hexadecane, benzene, toluene and xylene) degradation ability, two strains were selected for further study. The amplification and sequencing of the 16S rRNA gene showed that these two strains belonged to the genus Bacillus (Bacillus sp. L26 and Bacillus sp. L30). GC-MS analysis showed that strain L30 was the most effective in degrading n-alkane (C10-C27) from diesel after 7 days of cultivation in mineral medium. Both strains produced biosurfactants and showed emulsification activity, specially the strain L30. Alkane hydroxylase gene (group III), which is important for alkane biodegradation, was present in strains. As a result, this study indicated that these bacteria could have promising applications in hydrocarbon bioremediation.

A bitter pill to swallow: the need for better medications for drug-resistant tuberculosis in children.

The large and growing access gap between the number of children who become sick with drug-resistant tuberculosis (DR-TB) and those who are treated for the disease each year represents a significant health systems failure. While there are multiple reasons why children with DR-TB are not diagnosed and treated, a serious challenge is the medications used to treat the disease. This paper presents three child DR-TB cases who were treated incorrectly; the cases are used to illustrate some of the problems with existing second-line medications. Challenges, including the perception that the drugs are more dangerous than the disease, lack of proper dosing recommendations and formulations, and the high cost of current treatment, all contribute to a perverse situation in which the most vulnerable pediatric patients are provided with a lower standard of care. This situation can be reversed with novel partnerships and training models, pharmacokinetic studies of the relevant drugs, increased collaboration, and dedicated funding, grounded in a rights-based approach to DR-TB in children.

Isolation and characterization of hydrocarbon-degrading bacteria from gas station leaking-contaminated groundwater in the Southern Amazon, Brazil / Isolamento e caracterização de bactérias degradadoras de hidrocarbonetos de água subterrânea contaminada por vazamentos em posto de combustível no sul da Amazônia, Brasil

Abstract Twenty-three hydrocarbon-degrading bacteria strains were isolated from gas station leaking-contaminated groundwater located in the Southern Amazon, Brazil. Based on hydrocarbon (diesel, hexadecane, benzene, toluene and xylene) degradation ability, two strains were selected for further study. The amplification and sequencing of the 16S rRNA gene showed that these two strains belonged to the genus Bacillus (Bacillus sp. L26 and Bacillus sp. L30). GC-MS analysis showed that strain L30 was the most effective in degrading n-alkane (C10-C27) from diesel after 7 days of cultivation in mineral medium. Both strains produced biosurfactants and showed emulsification activity, specially the strain L30. Alkane hydroxylase gene (group III), which is important for alkane biodegradation, was present in strains. As a result, this study indicated that these bacteria could have promising applications in hydrocarbon bioremediation.

Resumo Vinte e três linhagens bacterianas degradadoras de hidrocarbonetos foram isoladas de água subterrânea contaminada por vazamento em posto de combustível no sul da Amazônia, Brasil. Com base na habilidade de degradar hidrocarbonetos (diesel, hexadecano, benzeno, tolueno e xileno), duas linhagens foram selecionadas para estudos posteriores. A amplificação e sequenciamento do gene 16S rRNA demonstrou que essas linhagens pertencem ao gênero Bacillus (Bacillus sp. L26 and Bacillus sp. L30). Análises de GC-MS mostraram que a linhagem L30 foi mais eficiente em degradar n-alcanos (C10-C27) presentes no diesel, após 7 dias de cultivo em meio mineral. Ambas as linhagens produziram biossurfactantes e apresentaram atividade emulsificante, especialmente a linhagem L30. O gene alcano hidroxilase (grupo III), o qual é importante para degradação de alcanos, foram detectados nas linhagens. Como resultado, este estudo indicou que essas linhagens bacterianas podem ser promissoras se aplicadas em processos de biorremediação.

Pharmacological evidence that the sympathetic nervous system mediates the increase in renin secretion produced by immobilization and head-up tilt in rats.

To determine the mechanism by which immobilization and head-up tilt under inactin anesthesia increase plasma renin activity (PRA), the effect of these stimuli on plasma levels of vasoactive intestinal polypeptide (VIP) were measured and the effect of the beta-adrenergic blocking drug, propranolol on the response of plasma renin activity determined. Increases in circulating VIP are known to stimulate secretion of renin. After 10 min of immobilization, plasma renin activity was increased and VIP in plasma was unchanged. After 30 min of tilting, plasma renin activity was also increased and VIP in plasma was unchanged. The increases in plasma renin activity were blocked by propranolol. Inactin anesthesia by itself increased plasma renin activity and this response was unaffected by propranolol and associated with a small decrease, rather than an increase in VIP in plasma. The results indicate that the responses of plasma renin activity to immobilization and head-up tilt are due to increased secretion of renin mediated by the sympathetic nervous system. On the other hand, the increase in secretion of renin produced by inactin anesthesia does not appear to be mediated by the sympathetic nervous system. There was no evidence that VIP was responsible for any of the increases.

Effects of reversible renal denervation on haemodynamic and excretory functions of the ipsilateral and contralateral kidney in the cat.

In anaesthetized cats reversible denervation of one kidney was performed by cooling of the left renal nerves to 3 degrees C for 16 min. The response of the left (ipsilateral) kidney was compared with the response of the right (contralateral) kidney twice in the same animal: (1) when the right kidney was still innervated, and (2) after it had been surgically denervated. Left renal nerve cooling did not cause any changes in arterial pressure. In the left kidney, blood flow, vascular conductance, sodium and water excretions increased, and renin release decreased. Simultaneously in the contralateral kidney, no haemodynamic changes were observed, glomerular filtration was only transiently decreased, whereas sodium and water excretion significantly decreased and renin release increased. When left renal nerve cooling was repeated after surgical denervation of the right kidney, similar changes were observed in the left (ipsilateral) kidney, whereas all contralateral effects were abolished. These experiments suggest that tonically active afferent fibres from one kidney exert a reflex inhibitory action on sympathetic activity directed to the contralateral kidney controlling tubular sodium reabsorption and renin release.

Afferent pathways of neural reno-renal reflexes controlling sodium and water excretion in the cat.

We have studied the role of afferent renal nerve fibres in anaesthetized cats in mediating the decrease in sodium and water excretion from the contralateral kidney caused by unilateral renal denervation. Transient denervation of one kidney obtained by cooling of the left renal nerves increases contralateral efferent renal nerve activity and decreased sodium and water excretion from the opposite kidney. The results observed in animals with intact neural pathways were compared with those obtained after the left kidney had been selectively deafferentated by cutting the dorsal roots from T9 to L4. Bilateral section of dorsal roots did not affect the increase in sodium and water excretion from the transiently denervated left kidney, but entirely abolished the decrease in sodium and water excretion from the contralateral kidney. Neither the left nor the right dorsal root section alone, affected the response of the contralateral right kidney. Our data demonstrate that afferent renal nerve fibres project bilaterally to the spinal cord and form the afferent branch of the reno-renal reflex by which one kidney can control the function of the opposite one.

Effects of adenosine-receptor agonists on renin release in anaesthetized rats.

OBJECTIVE: To investigate the effects of the interaction between adenosine receptors and renal nerves on renin release. MATERIALS AND METHODS: The effects on renin secretion of A1 (2-chloro-N6-cyclopentiladenosine) and A2 (2-hexynil-5'-N-ethyl-carboxamido-adenosine) adenosine-receptor agonists were studied in two groups of anaesthetized rats, each with one kidney surgically denervated. Arterial blood pressure and the renal blood flow of innervated and denervated kidneys were continuously recorded. Cannulae were inserted into both renal veins through femoral veins. After 1h of rest, A1 and A2 agonists were intravenously infused for 30 min in the two groups of rats. Plasma renin activity was measured by radioimmunoassay in blood samples drawn simultaneously from both renal veins and the femoral artery before and after the drug infusion. RESULTS: Infusions of A1 and A2 agonists produced comparable hypotensive effects. During A1 agonist administration, the heart rate decreased significantly, but it did not change after A2 agonist treatment. Renal blood flow was reduced by administration of the A1 agonist in both kidneys, while A2 agonist administration significantly reduced the renal blood flow of the innervated kidney only. The veno-arterial difference in plasma renin activity decreased after the A1 agonist infusion in both kidneys, but after the A2 agonist infusion it increased significantly in the innervated kidney only. CONCLUSIONS: Renal nerves do not influence the inhibition of renin release mediated by A1 adenosine receptors. In vivo, A2-receptor agonist administration can stimulate renin release only in the presence of intact renal nerves.

Effects of adenosine receptor agonists on renal function in anaesthetized rats.

OBJECTIVES: To investigate the effects of the interaction between adenosine receptors and renal nerves on urinary sodium excretion and glomerular filtration rate. METHODS AND DESIGN: The effects on water and sodium excretion and glomerular filtration rate of A1 [2-chloro-N6-cyclopentyl-adenosine (CCPA)] and A2 [2-hesinyl-5'-N-ethyl-carboxamido-adenosine (2HE-NECA)] adenosine agonists were studied in anaesthetized rats with one kidney surgically denervated. Arterial blood pressure, heart rate and rate of urine flow from each kidney were continuously recorded; inulin clearance was used as an index of glomerular filtration rate. The experiments were performed with three groups of rats, into which, after a control period of 20 min, CCPA, 2HE-NECA or vehicle was infused for two subsequent 20 min periods. RESULT: During infusion of CCPA, the slight decrease in arterial pressure was associated with a transient decrease in glomerular filtration rate and marked long-lasting decreases in heart rate, water and sodium excretion and fractional sodium excretion. The response of the innervated kidney was similar to the response of the denervated kidney. Infusion of 2HE-NECA caused decreases in arterial pressure, glomerular filtration rate and excretion of water and sodium associated with an increase in heart rate. The reduction of water and sodium excretion from the innervated kidney was larger than that from the denervated kidney. CONCLUSIONS: Activation both of A1 and of A2 receptor causes a reduction in urinary water and sodium excretion. The renal response to activation of A2 receptors is enhanced by the presence of renal nerves, whereas the response to activation of A1 receptors is not influenced by renal nerves.

Interactions between the sympathetic nervous system and atrial natriuretic factor in the control of renal functions.

We studied neural influences on the renal actions of atrial peptides in anaesthetized cats by comparing the response to atrial natriuretic factor (ANF) infusion in the innervated kidney and in the contralateral surgically denervated kidney. During ANF infusion arterial pressure decreased, the heart rate did not change and blood flow to both kidneys increased slightly. Vascular conductances became slightly but significantly higher in the denervated kidneys than in the controls. In both kidneys, the glomerular filtration rate increased transiently and significantly. Inhibition of renin release was more prompt and larger in the innervated than in the denervated kidneys. ANF infusion caused a significant increase in sodium and water excretion from both the innervated and denervated kidneys. However, the diuretic and natriuretic effect in the innervated kidneys, although proportionally greater than that in the denervated kidneys, was of shorter duration and subsided after 20 min of ANF infusion. Efferent renal nerve activity did not change during the initial 10 min of ANF infusion but thereafter increased progressively and significantly. We conclude that the effects of atrial peptides on renin release and excretory functions are influenced by renal nerve activity.

Role of the renal nerves in the control of renin synthesis during different sodium intakes in the rat.

OBJECTIVE: The aim of this study was to evaluate the role of the renal nerves in the regulation of renin synthesis in normotensive rats at different sodium balance. METHODS: Forty-eight male Sprague-Dawley rats were divided in six experimental groups, combining three diets at different NaCl content (normal 0.4%, low 0.04% or high 4.0%), and the surgical, bilateral renal denervation or the sham procedure. After 7 days of dietary treatment, all rats were sacrificed and plasma renin activity (PRA) was measured. Renin messenger RNA (mRNA) levels in the renal cortex were determined by semiquantitative polymerase chain reaction. RESULTS: PRA was higher in animals fed the low sodium diet compared with those at standard diet, while it was lower in animals fed the high sodium diet. Renal denervation decreased PRA in normal and low sodium groups, while it did not alter the PRA values in the high sodium group. Renin gene expression significantly increased in rats fed with the low sodium diet compared with the standard diet group, and significantly decreased in rats fed the high sodium diet Renal denervation significantly reduced renin mRNA levels in rats receiving the low sodium diet, but did not produce any significant change in normal or high-sodium groups. CONCLUSION: The activation of renin gene expression during sodium depletion in rats is dependent on the presence of the renal nerves, while the suppression of renin gene expression during a sodium load seems to be due to the macula densa mechanism alone.

Neural control of renin release.

Among the major mechanisms controlling the renal release of renin, renal nerves are known to exert a direct stimulating action on juxtaglomerular cells that is mediated by beta-adrenoceptors. Activation of the renal nerves also exerts an important permissive role in order to amplify and possibly accelerate responses to stimuli affecting the vascular and macula densa mechanisms. Reduction of renal perfusion pressure, intravenous infusion of furosemide, and captopril administration cause a greater increase in renin release from innervated kidneys than from denervated kidneys. A complex interaction between neural and non-neural mechanisms in the control of renin secretion is suggested. Efferent renal nerve activity controlling the renin secretion rate is mainly under the inhibitory influence of vagal afferent fibers originating from the cardiopulmonary region. Recent experiments have demonstrated that a similar reflex tonic inhibition of renin secretion is also exerted by renal afferent fibers.

Effects of erythropoietin administration on blood pressure and urinary albumin excretion in rats.

The effects of recombinant human erythropoietin (rHuEPO) administration on blood pressure and urinary albumin excretion were studied in normotensive Wistar-Kyoto rats (WKY), in spontaneously hypertensive rats (SHR), and in SHR rats treated with an angiotensin converting enzyme inhibitor (SHR-ACEi). Rats were housed in metabolic cages and treated with rHuEPO (150 U/kg body weight [bw] three times a week) for 6 weeks. Control animals received the vehicle only (0.25 mL of physiological saline). An angiotensin converting enzyme inhibitor was administered in the drinking water for 6 weeks (spirapril 5 mg/kg bw). Systolic blood pressure (SBP), and 24 h urinary albumin excretion (UAE) were measured once a week. No significant differences in SBP were observed between rHuEPO and vehicle-treated normotensive animals at the end of the treatment (171.9 +/- 4.9 v 172.1 +/- 5.6 mm Hg, respectively). After 6 weeks, SBP was significantly higher in SHR and SHR-ACEi groups treated with rHuEPO than in control groups (239.8 +/- 7.3 and 243.0 +/- 7.3 mm Hg v 218.1 +/- 6.0 and 187.9 +/- 4.6 mm Hg, respectively); UAE was significantly higher in groups treated with rHuEPO than in control groups (WKY: 265.9 +/- 19.5 v 127.0 +/- 12.3 microg/100 g bw, SHR: 1668.4 +/- 564.6 v 234.8 +/- 22.9 microg/100 g bw, and SHR-ACEi: 1522.7 +/- 448.3 v 143.0 +/- 18.9 microg/100 g bw, respectively). We concluded that erythropoietin treatment causes an increase in arterial pressure in SHR only, and an increase in UAE in both normotensive and hypertensive rats. The albuminuric effect was not entirely dependent on increased blood pressure. The treatment with an angiotensin converting enzyme inhibitor did not modify either the proteinuric or the pressor effects.

Behavioural stress blunts the creatinine clearance increase induced by a protein load in healthy subjects.

BACKGROUND: The aim of this study was to investigate how behavioural states related to different levels of stress affected the increments of glomerular filtration rate induced by an acute protein load. METHODS: Thirteen healthy subjects were enrolled. Each subject was studied from 9:00 h to 15:00 h on two consecutive days. In random order, after a protein meal (1.2 g/kg b.w. of protein), each subject was required to remain in a relaxing, sitting position (resting period, R), or to solve graphical and mathematical problems (behavioural stress period, S). Mean blood pressure (MBP) and heart rate (HR) were monitored by an ambulatory blood pressure device. Urine samples collected in each period were used to measure glomerular filtration rate (GFR, creatinine clearance) and urinary sodium excretion (UNa+V). RESULTS: Significant decreases in MBP and HR were observed during the resting period after the protein load, which significantly increased GFR. There was also a large increase of UNa+V. During S, the GFR changes were no longer seen whereas the increse of UNa+V was maintained. HR and MBP did not change compared to the prestimulus period. CONCLUSIONS: We conclude that in healthy subjects behavioural stress can blunt the increase in GFR that follows a protein load, presumably by neuro-humoral activated mechanisms. In our experimental conditions, behavioural stress did not affect UNa+V.

Analysis of the dynamics of renal vascular resistance and urine flow rate in the cat following electrical stimulation of the renal nerves.

In ten sino aortic denervated, vagotomized and aneasthetized cats, renal efferent nerves were stimulated for 30 s with trains of constant current pulses at frequencies in the range 5-30 Hz. The arterial pressure, heart rate, urine flow rate (electronic drop counter) and renal blood flow (electromagnetic technique) were recorded. Subsequent computer processing gave the true means of renal artery pressure (MRAP) and renal blood flow (MRBF) and hence the renal vascular resistance (MRVR), over each cardiac cycle. Recovery of MRVR after the end of stimulation exhibited two distinct time constants. The fast component had a time constant of 2.03 +/- 0.26 s and represented 60.2 +/- 1.71% of the recovery. The time constant of the slower component was 14.1 +/- 1.9 s and represented 36.0 +/- 1.6% of the recovery. The relationship between MRVR and stimulus frequency was sigmoidal with maximum sensitivity at stimulus frequencies of 12.6 +/- 0.76 Hz. Changes in urine flow rate, in contrast, followed a hyperbolic function with maximum response sensitivity occurring at very low stimulus frequencies. Changes in urine flow rate were 50% complete at stimulus frequencies of 5 Hz. Identification of two distinct components in the relaxation phase of renal vascular resistance leads to a reasonable hypothesis that 60% of total renal vascular resistance may lie proximal to the glomerulus, whereas 36% may be accounted for by the efferent arterioles.

Role of the renal nerves and angiotensin II in the renal function curve.

The relationship between renal perfusion pressure and urinary sodium is involved in arterial pressure regulation. The aim of this study was to investigate the role of renal nerves and angiotensin II in the pressure-natriuresis relationship. Experiments were performed in anaesthetised cats in which one kidney was surgically denervated. Renal perfusion pressure (RPP), renal blood flow (RBF) glomerular filtration rate (GFR, creatinine clearance), urinary volume (V) and sodium excretion (Una + V) were separately measured from both kidneys. RPP was progressively reduced in two consecutive steps by a suprarenal aortic snare. Two groups of animals were studied: the first without any pharmacological treatment (Untreated), the second during treatment with an angiotensin converting enzyme inhibitor (Captopril, 0.4 mg/Kg intravenously followed by an infusion of 0.4 mg/Kg/h). In the Untreated group RPP was reduced from 152.4 +/- 7.3 to 113.6 +/- 5.8 and 83.0 +/- 4.4 mmHg during the first and second step respectively. RBF and GFR were only slightly reduced during the second step of reduced RPP. In control conditions V and UNa + V were greater in the denervated compared to the innervated kidney. The graded decrease in RPP reduced both V and UNa + V in the innervated as well as in the denervated kidney. In the Captopril group V and UNa + V were larger than in the Untreated group in both the innervated and the denervated kidney. A decrease of RPP similar to that observed in the Untreated group, produced similar haemodynamic changes. Also in the Captopril group the graded decrease in RPP reduced both V and UNa + V in the innervated as well as in the denervated kidney. Matching UNa + V against RPP values significant correlations were found in the innervated and denervated kidneys of both groups. Both renal denervation and ACE inhibition were accompanied by an increased gain of the pressure-natriuresis curve, but only renal denervation shifted the crossing of the pressure axis to the left. In the ACE inhibited animals renal denervation only shifted the curve to the left. In conclusion our data suggest that i) at each level of RPP renal nerves and angiotensin II decrease renal sodium excretion, ii) renal nerves and angiotensin II increase the slope of the renal function curve, iii) renal nerves shift to the right the renal function curve.

Do renal afferent fibres modulate the function of the contralateral kidney?

Denervation of one kidney has been shown to induce a prompt decrease in sodium and water excretion from the contralateral kidney. The present study was designed to clarify whether this response is due to suppression of a tonic inhibitory renorenal reflex. Experiments were performed in anaesthetized cats in which the renal nerves of the left kidney were transiently blocked by cooling and the effects of this blockade on either kidney were studied in three different groups of animals. The decrease in sodium and water excretion from the contralateral (right) kidney observed in the sham-operated group (intact dorsal roots) was still present, and substantially unchanged, in the second group of animals in which the ipsilateral (left) dorsal roots from T9 to L4 were cut. In the third group of cats, bilateral dorsal root section entirely abolished the response of the contralateral kidney to renal nerve cooling. These experiments demonstrate that the contralateral decrease in sodium and water excretion is due to the block of afferent renal nerve fibres which project bilaterally to the spinal cord.

Role of the renal nerves in the natriuretic response to vasopressin infusion.

The present study was designed to determine whether renal nerves influence the natriuretic response to an infusion of vasopressin. Experiments were performed on anaesthetized rats in which the response to vasopressin of the innervated kidney was compared with that of the contralateral surgically denervated kidney. During the vasopressin infusion the natriuretic effect was evident in both kidneys and was proportionally greater in the innervated kidney than in the denervated one. Efferent renal nerve activity, recorded in three additional animals, decreased during the vasopressin infusion. Our data demonstrate that the natriuretic response of the innervated kidney is larger than that of the denervated kidney, probably because of an associated decrease in efferent renal nerve activity.

Regulation of sodium and water excretions by neural renorenal reflexes in the cat.

The reduction in sodium and water excretion observed in the right kidney when the left kidney is subjected to transient denervation, is entirely abolished by bilateral section of the dorsal roots from T9 to L4, whereas section of the left dorsal roots only, at the same spinal level, does not affect the contralateral renal response to left renal nerve cooling. The possibility that the bilateral dorsal roots section abolished the response of the right kidney because the afferent fibres from the left kidney travel in the right dorsal roots was explored in the present study. Experiments were performed in anaesthetized cats in which reversible denervation of the left kidney was done by cooling of left renal nerves (for 10 min) after cutting the right dorsal roots from T9 to L4. Cooling of left renal nerves caused a large increase in sodium and water excretion from the left kidney and a prompt decrease in sodium and water excretion from the right kidney. During the cooling period arterial pressure did not change and glomerular filtration rate slightly increased in the left kidney only. The results obtained in this group of animals were not significantly different from those previously observed in sham-operated cats or in cats with section of left dorsal roots only. As the contralateral antidiuretic and antinatriuretic response to renal denervation survives dorsal root section on either side but is prevented by bilateral section, this demonstrates that the inhibitory renal afferent fibres responsible for this renorenal reflex are distributed bilaterally to spinal dorsal roots.

Isolation and characterization of hydrocarbon-degrading bacteria from gas station leaking-contaminated groundwater in the Southern Amazon, Brazil

Abstract Twenty-three hydrocarbon-degrading bacteria strains were isolated from gas station leaking-contaminated groundwater located in the Southern Amazon, Brazil. Based on hydrocarbon (diesel, hexadecane, benzene, toluene and xylene) degradation ability, two strains were selected for further study. The amplification and sequencing of the 16S rRNA gene showed that these two strains belonged to the genus Bacillus (Bacillus sp. L26 and Bacillus sp. L30). GC-MS analysis showed that strain L30 was the most effective in degrading n-alkane (C10-C27) from diesel after 7 days of cultivation in mineral medium. Both strains produced biosurfactants and showed emulsification activity, specially the strain L30. Alkane hydroxylase gene (group III), which is important for alkane biodegradation, was present in strains. As a result, this study indicated that these bacteria could have promising applications in hydrocarbon bioremediation.

Resumo Vinte e três linhagens bacterianas degradadoras de hidrocarbonetos foram isoladas de água subterrânea contaminada por vazamento em posto de combustível no sul da Amazônia, Brasil. Com base na habilidade de degradar hidrocarbonetos (diesel, hexadecano, benzeno, tolueno e xileno), duas linhagens foram selecionadas para estudos posteriores. A amplificação e sequenciamento do gene 16S rRNA demonstrou que essas linhagens pertencem ao gênero Bacillus (Bacillus sp. L26 and Bacillus sp. L30). Análises de GC-MS mostraram que a linhagem L30 foi mais eficiente em degradar n-alcanos (C10-C27) presentes no diesel, após 7 dias de cultivo em meio mineral. Ambas as linhagens produziram biossurfactantes e apresentaram atividade emulsificante, especialmente a linhagem L30. O gene alcano hidroxilase (grupo III), o qual é importante para degradação de alcanos, foram detectados nas linhagens. Como resultado, este estudo indicou que essas linhagens bacterianas podem ser promissoras se aplicadas em processos de biorremediação.