From freezing to functioning: cellular strategies of cold-adapted bacteria for surviving in extreme environments.

The ability of cold-adapted bacteria to survive in extreme cold and diverse temperatures is due to their unique attributes like cell membrane stability, up-regulation of peptidoglycan biosynthesis, increased production of extracellular polymeric substances, and expansion of membrane pigment. Various cold-adapted proteins, including ice-nucleating proteins (INPs), antifreeze proteins (AFPs), cold shock proteins (Csps), and cold-acclimated proteins (CAPs), help the bacteria to survive in these environments. To sustain cells from extreme cold conditions and maintain stability in temperature fluctuations, survival strategies at the molecular level and their mechanism play significant roles in adaptations in cryospheric conditions. Furthermore, cold shock domains present in the multifunctional cold shock proteins play crucial roles in their adaptation strategies. The considerable contribution of lipopeptides, osmolytes, and membrane pigments plays an integral part in their survival in extreme environments. This review summarizes the evolutionary history of cold-adapted bacteria and their molecular and cellular adaptation strategies to thrive in harsh cold environments. It also discusses the importance of carotenoids produced, lipid composition, cryoprotectants, proteins, and chaperones related to this adaptation. Furthermore, the functions and mechanisms of adaptations within the cell are discussed briefly. One can utilize and explore their potential in various biotechnology applications and their evolutionary journey by knowing the inherent mechanism of their molecular and cellular adaptation to cold climatic conditions. This review will help all branches of the life science community understand the basic microbiology of psychrophiles and their hidden prospect in life science research.

Biodegradation of DEP, DIBP, and BBP by a psychrotolerant Sphingobium yanoikuyae strain P4: Degradation potentiality and mechanism study.

Phthalic acid esters (PAEs) are human made chemicals widely used as plasticizers to enhance the flexibility of plastic products. Due to the lack of chemical bonding between phthalates and plastics, these materials can easily enter the environment. Deleterious effects caused by this chemo-pollutant have drawn the attention of the scientific community to remediate them from different ecosystem. In this context, many bacterial strains have been reported across different habitats and Sphingobium yanoikuyae strain P4 is among the few psychrotolerant bacterial species reported to biodegrade simple and complex phthalates. In the present study, biodegradation of three structurally different PAEs viz., diethyl phthalate (DEP), di-isobutyl phthalate (DIBP), and butyl benzyl phthalate (BBP) have been investigated by the strain P4. Quantitative analyses through High-performance liquid chromatography (HPLC) revealed that the bacterium completely degraded 1 g/L of DEP, DIBP, and BBP supplemented individually in minimal media pH 7.0 within 72, 54, and 120 h of incubation, respectively, at 28 °C and under shake culture condition (180 rpm). In addition, the strain could grow in minimal media supplemented individually with up to 3 g/L of DEP and 10.0 g/L of DIBP and BBP at 28 °C and pH 7.0. The strain also could grow in metabolites resulting from biodegradation of DEP, DIBP, and BBP, viz. n-butanol, isobutanol, butyric acid, ethanol, benzyl alcohol, benzoic acid, phthalic acid, and protocatechuic acid. Furthermore, phthalic acid and protocatechuic acid were also detected as degradation pathway metabolites of DEP and DIBP by HPLC, which gave an initial idea about the biodegradation pathway(s) of these phthalates.

Acute onset movement disorders in diabetes mellitus: A clinical series of 59 patients.

BACKGROUND AND PURPOSE: No previous study has assessed the frequency and clinical-radiological characteristics of patients with diabetes mellitus (DM) and acute onset nonchoreic and nonballistic movements. We conducted a prospective study to investigate the spectrum of acute onset movement disorders in DM. METHODS: We recruited all the patients with acute onset movement disorders and hyperglycemia who attended the wards of three hospitals in West Bengal, India from August 2014 to July 2021. RESULTS: Among the 59 patients (mean age = 55.4 ± 14.3 years, 52.5% men) who were included, 41 (69.5%) had choreic or ballistic movements, and 18 (30.5%) had nonchoreic and nonballistic movements. Ballism was the most common movement disorder (n = 18, 30.5%), followed by pure chorea (n = 15, 25.4%), choreoathetosis (n = 8, 13.6%), tremor (n = 5, 8.5%), hemifacial spasm (n = 3, 5.1%), parkinsonism (n = 3, 5.1%), myoclonus (n = 3, 5.1%), dystonia (n = 2, 3.4%), and restless leg syndrome (n = 2, 3.4%). The mean duration of DM was 9.8 ± 11.4 years (89.8% of the patients had type 2 DM). Nonketotic hyperglycemia was frequently (76.3%) detected. The majority (55.9%) had no magnetic resonance imaging (MRI) changes; the remaining showed striatal hyperintensity. Eight patients with MRI changes exhibited discordance with sidedness of movements. Most of the patients (76.3%) recovered completely. CONCLUSIONS: This is the largest clinical series depicting the clinical-radiological spectrum of acute onset movement disorders in DM. Of note was that almost one third of patients had nonchoreic and nonballistic movements. Our findings highlight the importance of a capillary blood glucose measurement in patients with acute or subacute onset movement disorders, irrespective of their past glycemic status.

Neuroimaging of Diabetic Striatopathy: More Questions than Answers.

BACKGROUND: Diabetic striatopathy (DS), coined as a generic term, has been defined as a hyperglycemic condition associated with either one of the two following conditions: chorea/ballism or striatal hyperdensity on computed tomography or striatal hyperintensity on T1-weighted magnetic resonance imaging. This review highlights those "gray areas," which need further exploration to understand better hyperglycemia-induced striatal changes and diverse movement disorder phenotypes associated with these changes. RESULTS AND DISCUSSION: We searched in PubMed and Google Scholar the terms "diabetes mellitus," "movement disorders," "diabetic striatopathy," "chorea," "hemichorea," "ballism," "hemichorea-hemiballism," and "neuroradiology" in various combinations (time range from 1980 to March 2022). We selected the publications about our topic of discussion. SUMMARY: Hemichorea-hemiballismus is the most commonly associated movement disorder in DS, and the putamen is the most frequently affected anatomical region. The exact pathophysiological mechanisms remain elusive. Clinical-radiological discordance is not rare. Complete reversal of symptoms with the resolution of the imaging findings is the most prevalent outcome in patients with DS. Dramatic improvement of chorea can be achieved by either insulin monotherapy or combination therapy of insulin and D2-blocker or, in some cases, even spontaneously. CONCLUSION: The term "diabetic striatopathy" is ambiguous and controversial. Pathological mechanisms behind clinical-radiological discordance in hyperglycemia-induced striatopathy need further exploration through well-designed studies. We propose a classification of DS that includes symptomatic DS (striatal neuroimaging lesions in association with a clinically evident movement disorder and hyperglycemia), clinically isolated DS (clinically evident movement disorders without striatal changes in neuroimaging), and radiologically isolated DS.

Ornithine carbamoyltransferase from psychrophiles to thermophiles: structural evolution of catalytic fold to accommodate physiological diversity.

Here, we have analyzed the enzyme ornithine carbamoyltransferase (OCTase) in different classes of microorganisms belonging to psychrophiles, mesophiles and thermophiles. This OCTase catalyzes the formation of citrulline from carbamoyl phosphate (CP) and ornithine (ORN) in arginine biosynthesis pathway and has certain unique adaptations to regulate metabolic pathways in extreme conditions. The tertiary structure of OCTase showed two binding domains, the CP domain and ORN-binding domain at N and C terminals, respectively. We propose general acid-base catalysis in Pseudomonas gessardii between His259 and Asp220 in which later may act as a recipient of proton in the process. The comparative docking analysis showed that substrate-binding loops have been evolved to accommodate their lifestyles across the physiological temperature range where two substrates bind on two distinct loops in psychrophiles and mesophiles, whereas both the substrates bind on a single-substrate-binding loop in thermophiles and bring down the flexibility of the active site pocket to improve its evolutionary fitness.

Biodegradation of organophosphorus pesticide chlorpyrifos by Sphingobacterium sp. C1B, a psychrotolerant bacterium isolated from apple orchard in Himachal Pradesh of India.

A psychrotolerant Sphingobacterium sp. was isolated from the apple orchard situated in the Kufri region of Shimla, Himachal Pradesh, India using an enrichment culture technique having chlorpyrifos (CP) as the sole source of carbon and energy. Based on biochemical characterization and 16S rRNA analysis, the strain was identified as Sphingobacterium sp. C1B. The bacterium C1B was able to degrade chlorpyrifos ≥ 42 ppm and ≥ 36 ppm within 14 days at 20 °C and 15 °C, respectively. The strain was also able to degrade chlorpyrifos ≤ 35 ppm at 28 °C within 14 days. The enzyme organophosphorus hydrolase might be responsible for the initial degradation of CP by the strain C1B. Based on the HPLC and GCMS analysis, a probable degradation pathway has been proposed, which followed the path from chlorpyrifos to 3,5,6-trichloro-2-pyridinol to benzene, 1,3-bis (1,1-dimethylethyl) and then entered into the TCA cycle. Our current study revealed that the bacterium C1B was found to be a useful strain for the degradation of pesticide chlorpyrifos in the cold climatic environment.

The disease presentation of Moyamoya angiopathy in Eastern India.

INTRODUCTION: Clinical spectrum of Moyamoya angiopathy (MMA) differs across populations with different ethnicity. This study, the largest one done among Indian population was undertaken to assess clinico-radiological profile of MMA patients in eastern India. METHODS: A single centre cross-sectional study was undertaken among 76 MMA cases. Each patient was evaluated for epidemiological, clinical and radiological characteristics. SPSS 25 was used for statistical analysis. P < 0.05 was taken as statistically significant. RESULTS: 36 (47.4%) were children without gender preponderance. There were female predominance among adults (male:female = 1:2.33). Mean age at onset of first neurological symptoms for children was 4.2 ± 2.0years, followed by 34.9 ± 58.2months of latency with final diagnosis at the mean age of 7.4 ± 3.5years. For adults, mean age of onset of first neurological symptoms was 31.5 ± 12.3years, followed by 14.7 ± 41.7months time gap and diagnosed at the mean age of 33.5 ± 12.5years. There was a statistically significant difference between child and adult regarding the diagnostic latency (p = 0.035). Fixed motor weakness (FMW) was the predominant symptom across the whole disease course. Among children predominant first neurological symptom was fixed motor weakness (FMW) (52.8%), followed by seizures (22.2%). FMW was predominant (55%) first neurological complaint, followed by headache (22.5%) among adults. Seizure was more prevalent among children both as first (p = 0.002) and presenting symptom at the time of diagnosis (p = 0.048). Over the course of the disease seizure was more common among children (p = 0.001), while headache was more common among adults (p = 0.017). Recurrence of symptoms was more common among children (p = 0.059). Infarcts were more common among children (91.7%) than adults (72.5%), while hemorrhage was seen only among adults (25%) (p = 0.004). Isolated cerebral cortex was involved more commonly among children (59.4%) than adults (36.1%), while isolated subcortical involvement was seen only among adults (19.4%) (p = 0.016). Majority of the MMA cases were of Suzuki stage 4 (39.5%) and 5 (27.6%). Brain atrophy was associated with diagnostic latency (p = 0.009). CONCLUSION: Indian Moyamoya presents similar to disease presentation in Caucasian and Japanese patients. It is a frequently overlooked cause of stroke in young, often with various non-motor presentations, failure to recognize which leads to delay in diagnosis. Radiological burden disproportionate to number of acute vascular events, with subtle neurological manifestations like headache or seizure, often with cognitive decline, should raise suspicion of MMA.

Impact of COVID -19 on children: special focus on the psychosocial aspect.

Although medical literature shows that children are minimally susceptible to 2019-Corona virus disease (COVID-19), they are hit the hardest by psychosocial impact of this pandemic. Being quarantined in homes and institutions may impose greater psychological burden than the physical sufferings caused by the virus. School closure, lack of outdoor activity, aberrant dietary and sleeping habits are likely to disrupt children's usual lifestyle and can potentially promote monotony, distress, impatience, annoyance and varied neuropsychiatric manifestations. Incidences of domestic violence, child abuse, adulterated online contents are on the rise. Children of single parent and frontline workers suffer unique problems. The children from marginalized communities are particularly susceptible to the infection and may suffer from extended ill-consequences of this pandemic, such as child labor, child trafficking, child marriage, sexual exploitation and death etc. Parents, pediatricians, psychologists, social workers, hospital authorities, government and non-governmental organizations have important roles to play to mitigate the psychosocial ill-effects of COVID-19 on children and adolescents. To provide the basic amenities, social security, medical care, and to minimize the educational inequities among the children of the different strata of the society are foremost priorities.

A review on remediation of cyanide containing industrial wastes using biological systems with special reference to enzymatic degradation.

Cyanide is a nitrile which is used extensively in many industries like jewelry, mining, electroplating, plastics, dyes, paints, pharmaceuticals, food processing, and coal coking. Cyanides pose a serious health hazard due to their high affinity towards metals and cause malfunction of cellular respiration by inhibition of cytochrome c oxidase. This inhibition ultimately leads to histotoxic hypoxia, increased acidosis, reduced the functioning of the central nervous system and myocardial activity. Different physicochemical processes including oxidation by hydrogen peroxide, alkaline chlorination, and ozonization have been used to reduce cyanide waste from the environment. Microbial cyanide degradation which is considered as one the most successful techniques is used to take place through different biochemical/metabolic pathways involving reductive, oxidative, hydrolytic or substitution/transfer reactions. Groups of enzymes involved in microbial degradation are cyanidase, cyanide hydratase, formamidase, nitrilase, nitrile hydratase, cyanide dioxygenase, cyanide monooxygenase, cyanase and nitrogenase. In the future, more advancement of omics technologies and protein engineering will help us to recoup the environment from cyanide effluent. In this review, we have discussed the origin and environmental distribution of cyanide waste along with different bioremediation pathways and enzymes involved therein.

Molecular insights into the activity and mechanism of cyanide hydratase enzyme associated with cyanide biodegradation by Serratia marcescens.

The present study provides molecular insights into the activity and mechanism of cyanide hydratase enzyme associated with degradation of cyanide compounds, using Serratia marcescens RL2b as a model organism. Resting cells harvested after 20 h achieved complete degradation of 12 mmol l- 1 cyanide in approximately 10 h. High-performance liquid chromatography analysis of reaction samples revealed formation of formamide as the only end product, which confirmed the presence of cyanide hydratase activity in S. marcescens RL2b. Comparative structural analysis with the other nitrilase family proteins, which was carried out using a sequence of cyanide hydratase from a phylogenetically related strain S. marcescens WW4, also revealed subtle but significant differences in amino acid residues of the substrate-binding pocket and catalytic triad (Cys-Lys-Glu).

A simple HPLC-DAD method for simultaneous detection of two organophosphates, profenofos and fenthion, and validation by soil microcosm experiment.

Indiscriminate use of two broad spectrum pesticides, profenofos and fenthion, in agricultural system, often results in their accumulation in a non-target niche and leaching into water bodies. The present study, therefore, aims at developing a simple and rapid HPLC method that allows simultaneous extraction and detection of these two pesticides, especially in run-off water. Extraction of the two pesticides from spiked water samples using dichloromethane resulted in recovery ranging between 80 and 90%. An HPLC run of 20 min under optimized chromatographic parameters (mobile phase: methanol (75%) and water (25%); flow rate of 0.8 ml min-1; diode array detector at wavelength 210 nm) resulted in a significant difference in retention times of two pesticides (4.593 min) which allows a window of opportunity to study any possible intermediates/transformants of the parent compounds while evaluating run-off waters from agricultural fields. The HPLC method developed allowed simultaneous detection of profenofos and fenthion with a single injection into the HPLC system with 0.0328 mg l-1 (32.83 ng ml-1) being the limit of detection (LOD) and 0.0995 mg l-1 (99.5 ng ml-1) as the limit of quantification (LOQ) for fenthion; for profenofos, LOD and LOQ were 0.104 mg l-1 (104.50 ng ml-1) and 0.316 mg l-1 (316.65 ng ml-1), respectively. The findings were further validated using the soil microcosm experiment that allowed simultaneous detection and quantification of profenofos and fenthion. The findings indicate towards the practical significance of the methodology developed as the soil microcosm experiment closely mimics the agricultural run-off water under natural environmental conditions.

Psychrotolerant Sphingobacterium kitahiroshimense LT-2 Isolated from Dhundi Glacier, Himachal Pradesh: Origin Prediction and Future Application.

A psychrotolerant bacterium, isolated from Dhundi Glacier, Himachal Pradesh (India) was identified as Sphingobacterium kitahiroshimense LT-2 on the basis of biochemical, molecular and phylogenetic analysis. Sphingobacterium kitahiroshimense was first reported from Japan and was isolated from the city of Kitahiroshima, Hokkaido, Japan. In this report we have discussed about the origin of our strain and predicted that air masses and dust associated microbial cells transportation phenomena may be applicable for the origin of this species in this region. Enzymes and secondary metabolites secreted by the genus Sphingobacterium have enormous potentiality regarding their biotechnological application. Preliminary study of our strain based on metabolic profiling through HPLC showed many new metabolites were secreted by the bacterium when grown in presence of different sugar medium at 28 °C. As far as our knowledge this is the first report about Sphingobacterium species isolated from this region. This preliminary finding will help to draw an idea about the bacterial population in this Himalayan Glaciers (in HP) as well as biotechnological application of this strain can be explored further.

Interactions among filamentous fungi Aspergillus niger, Fusarium verticillioides and Clonostachys rosea: fungal biomass, diversity of secreted metabolites and fumonisin production.

BACKGROUND: Interactions among fungi colonizing dead organic matter involve exploitation competition and interference competition. Major mechanism of interference competition is antibiosis caused by secreted secondary metabolites. The effect of competition on secondary metabolite production by fungi is however poorly understood. Fungal biomass was rarely monitored in interaction studies; it is not known whether dominance in pairwise interactions follows congruent patterns. RESULTS: Pairwise interactions of three fungal species with different life styles were studied. The saprophyte Aspergillus niger (A.n.), the plant pathogen Fusarium verticillioides (F.v.), and the mycoparasite Clonostachys rosea (C.r.) were grown in single and dual cultures in minimal medium with asparagine as nitrogen source. Competitive fitness shifted with time: in dual C.r./F.v. cultures after 10 d F.v. grew well while C.r. was suppressed; after 20 d C.r. recovered while F.v. became suppressed; and after 30 d most F.v. was destroyed. At certain time points fungal competitive fitness exhibited a rock-paper-scissors pattern: F.v. > A.n., A.n. > C.r., and C.r. > F.v. Most metabolites secreted to the medium at early stages in single and dual cultures were not found at later times. Many metabolites occurring in supernatants of single cultures were suppressed in dual cultures and many new metabolites not occurring in single cultures were found in dual cultures. A. niger showed the greatest ability to suppress the accumulation of metabolites produced by the other fungi. A. niger was also the species with the largest capacity of transforming metabolites produced by other fungi. Fumonisin production by F. verticillioides was suppressed in co-cultures with C. rosea but fumonisin B1 was not degraded by C. rosea nor did it affect the growth of C. rosea up to a concentration of 160 µg/ml. CONCLUSIONS: Competitive fitness in pairwise interactions among fungi is incongruent, indicating that species-specific factors and/or effects are involved. Many metabolites secreted by fungi are catabolized by their producers at later growth stages. Diversity of metabolites accumulating in the medium is stimulated by fungus/fungus interactions. C. rosea suppresses the synthesis of fumonisins by F. verticillioides but does not degrade fumonisins.

Profenofos, an Acetylcholinesterase-Inhibiting Organophosphorus Pesticide: A Short Review of Its Usage, Toxicity, and Biodegradation.

Pesticides play an important role in the protection of different crops. Among the diverse sets of pesticides used all over the world, the organophosphates are the most widely used group. Profenofos [O-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothioate] is one of the most largely used organophosphate insecticides on field crops, vegetables, and fruit crops. The World Health Organization classifies this compound as moderately hazardous (Toxicity Class II), and its residues have been found in vegetables like okra [ (L.) Moench], gooseberries ( sp.), green chilies [ (L.)], curry leaves [ (L.) Spreng], mint leaves [ (L.)], and coriander leaves [ (L.)]. Dietary intake of profenofos (PFF) is the major exposure pathway for humans. When applied to agricultural fields, PFF residues spread into every part of the environment: ambient air, surface water, and soil. In this review, we discuss the worldwide usage of PFF pesticide, its toxic effects on humans and other living organisms in the environment, and biodegradation of this chemical by various microbial strains. To date, no complete biodegradation pathway has been established for PFF pesticide, calling for a study of this nature.

Perception, awareness and practice of research-oriented medical education among undergraduate students of a medical college in Kolkata, West Bengal.

BACKGROUND: The addition of research-oriented medical education (ROME) to the existing curriculum could promote logical thinking, rapid literature search and a better understanding of research methodology. Creation of research temperament could lead to innovations in healthcare. We assessed the perception, awareness and practice of ROME among undergraduate students. METHODS: We conducted a cross-sectional survey among 234 students of R.G. Kar Medical College, Kolkata selected by the simple random sampling technique. Data were collected using a pre-designed, pre-tested, validated questionnaire by direct interviews. RESULTS: The mean (SD) perception score was 44.2 (5.03). Students from outside West Bengal (p=0.05), women (p=0.03) and students whose parents were doctors (p=0.01) had significantly higher scores. Students in the second and fourth semesters had a better perception than those in the sixth and eighth semesters. Awareness of research fellowships granted to undergraduate students such as the Indian Council of Medical Research-Short-term studentship (ICMR-STS) was low among the second semester students (13.9%), but more than half (59.3%) of the students in the eighth semester were aware (difference across semesters, p<0.001). Awareness about journals, conferences and 'research bodies promoting student research' was low. Students in the senior semesters spent more time on research (6th semester 72.2% and 8th semester 88.9%) than those in the junior semesters (2nd: 66.7% and 4th: 77.8%; difference across semesters, p=0.03). About 3% of students participated in extracurricular research and/or had presented work at a conference. CONCLUSION: There is a good perception about the need for research but a lack of awareness of the why and how, as well as hardly any practice of ROME among medical students of this medical college.

Biodiversity and species identity shape the antifungal activity of bacterial communities.

Soils host diverse communities of interacting microbes and the nature of interspecific interactions is increasingly recognized to affect ecosystem-level processes. Antagonistic interactions between bacteria and fungi are of particular relevance for soil functioning. A number of soil bacteria produce secondary metabolites that inhibit eukaryotic growth. Antibiosis may be stimulated in the presence of competing bacteria, and we tested if biodiversity within bacterial communities affects their antagonistic activity against fungi and fungal-like species. We set up Pseudomonas communities of increasing diversity and measured the production of the broad spectrum antifungal compound 2,4-DAPG and their antagonistic activity against different eukaryotes. Diversity increased DAPG concentration and antifungal activity, an effect due to a combination of identity and interactions between species. Our results indicate that investment of pseudomonads into broad spectrum anti-eukaryotic traits is determined by both community composition and diversity and this provides new avenues to understand interactions between bacterial and fungal communities.

A higher dietary ratio of long-chain omega-3 to total omega-6 fatty acids for prevention of COX-2-dependent adenocarcinomas.

Compelling evidence that daily low-dose aspirin decreases risk for a number of adenocarcinomas likely reflects the fact that a modest but consistent inhibition of cyclooxygenase-2 (COX-2) activity can have a meaningful protective impact on risk for such cancers. The cancer-promoting effects of COX-2 are thought to be mediated primarily by prostaglandin E2 (PGE2), synthesized from arachidonic acid. The long-chain omega-3s eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), abundant in many fatty fish, can interfere with the availability of arachidonate to COX-2 by multiple complementary mechanisms; moreover, the PGE3 produced by COX-2 from EPA is a competitive inhibitor of the receptors activated by PGE2. These considerations have given rise to the hypothesis that a high dietary intake of EPA/DHA, relative to omega-6 (from which arachidonate is generated), should lessen risk for a number of adenocarcinomas by impeding PGE2 production and activity-while not posing the risk to vascular health associated with COX-2-specific nonsteroidal antiinflammatory agents. Analyses that focus on studies in which the upper category of fish consumption (not fried or salt-preserved) is 2 or more servings weekly, and on studies that evaluate the association of long-term fish oil supplementation with cancer risk yields a number of findings that are consistent with the hypothesis. Further studies of this nature may help to clarify the impact of adequate regular intakes of long-chain omega-3 on cancer risk, and perhaps provide insight into the dose-dependency of this effect.

Comparative analysis of SilA-laccase mediated degradation of ciprofloxacin, norfloxacin and ofloxacin and interpretation of the possible catalytic mechanism.

Fluoroquinolones (FQs) are the most commonly used antimicrobial drugs and regardless of their advantages in the healthcare sector, the pollution of these antimicrobial drugs in the environment has big concerns about human and environmental health. The presence of these antibiotic drugs even at the lowest concentrations in the environment has resulted in the emergence and spread of antibiotic resistance. Hence, it is necessary to remediate these pollutants from the environment. Previously alkaline laccase (SilA) from Streptomyces ipomoeae has been demonstrated to show degrading potentials against two of the FQs, Ciprofloxacin (CIP) and Norfloxacin (NOR); however, the molecular mechanism was not elucidated in detail. In this study, we have analyzed the possible molecular catalytic mechanism of FQ degrading SilA-laccase for the degradation of the FQs, CIP, NOR and Ofloxacin (OFL) using three-dimensional protein structure modeling, molecular docking and molecular dynamic (MD) studies. The comparative protein sequence analysis revealed the presence of tetrapeptide conserved catalytic motif, His102-X-His104-Gly105. After evaluating the active site of the enzyme in depth using CDD, COACH and S-site tools, we have identified the catalytic triad composed of three conserved amino acid residues, His102, Val103 and Tyr108 with which ligands interacted during the catalysis process. By analyzing the MD trajectories, it is revealed that the highest degradation potential of SilA is for CIP followed by NOR and OFL. Ultimately, this study provides the possible comparative catalytic mechanism for the degradation of CIP, NOR and OFL by the SilA enzyme.Communicated by Ramaswamy H. Sarma.