Peer Reviewed Journal Articles (Inter.) (M,F&B)
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- ItemPhysicochemical, microstructural, and microbial qualities of dehydrated Tuna chunks: Effects of microwave power and drying methods(Wiley, 2021-03-02)Boneless Tuna chunks were marinated using spices and were dried in a microwave vacuum dryer at different powers (600 W [T1], 650 W [T2], and 700 W [T3]) for 2 hr. Another two batches were prepared by hot air drying (55 ± 5°C) (HAD) and sun drying (SD) to a comparable moisture content obtained by sample T2. The moisture content was 44.69 g/100 g, 39.26 g/100 g, 24.40 g/100 g, 32.80 g/100 g, and 38.45 g/100 g for T1, T2, T3, SD, and HAD, respectively. Increasing microwave power level resulted in reduced moisture content and water activity in dried tuna chunks. Analysis of SEM indicated a tough morphology in SD and HAD whereas a smooth morphology in microwave vacuum dried samples. Results of FTIR analysis indicated higher protein denaturation with an increase in microwave power. Oxidation of lipids increased significantly (p < .05) with microwave power as displayed by higher peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) values in T3 and T2 samples. Microbial spoilage was faster in T1 samples compared to T2 and T3. On the other side, sun-dried and hot air-dried samples have shown poor rehydration and color attributes but better oxidative stability than microwave vacuum dried samples.
- ItemGenotypes and phenotypes of methicillin-resistant staphylococci isolated from shrimp aquaculture farms(Wiley, 2021-07-19)The population of methicillin-resistant (MR) staphylococci in aquatic environment is rarely investigated. Here, we characterized a collection of MR staphylococci recovered from shrimp aquaculture farms (n = 37) in Kerala, India. A total of 261 samples yielded 47 MR isolates (16 S. aureus, 13S. haemolyticus, 11S. epidermidis, 3 S. saprophytics and 2 each of S.intermedius and S. kloosii). Multi-drug resistance was evident in 72.3% of the isolates, with resistance mainly towards erythromycin (78.7%), norfloxacin and trimethoprim-sulfamethoxazole (53.2%), and gentamicin (34%). Major resistance genes identified included mecA (100%), ermC (38.3%), aacA-aphD (21.3%), tetK (14.9%) and tetM (21.3%). Almost 60% of the isolates carried type V SCCmec (Staphylococcal Cassette Chromosome mec), and the remaining harboured untypeable SCCmec elements. Comprehensive genotyping of the methicillin-resistant Staphylococcus aureus isolates revealed high prevalence of ST772-t345-V (sequence type-spa type-SCCmec type) (75%), followed by minor representations of ST6657-t345-V and ST3190-t12353. The isolates of S. haemolyticus and S. epidermidis were genotypically diverse as shown by their pulsed-field gel electrophoresis (PFGE) profiles. Genes encoding staphylococcal enterotoxins were observed in 53.2% of the isolates. Various genes involved in adhesion and biofilm formation were also identified. In conclusion, our findings provide evidence that shrimp aquaculture settings can act as reservoirs of methicillin-resistant staphylococci.
- ItemFood grade zinc oxide bulk particle composite can replace the toxic zinc oxide nano composite towards the control of pathogenic and spoilage bacteria(Oxford Academic, 2020-12-15)ZnO-Nanoparticle-Chitosan (ZnO-NP-CH) composite has potential biomedical and food applications due to its better antimicrobial activity. However, the presence of nano-metal-oxide in the composite makes the material unsuitable for any food applications. Moreover, the cost involved in the preparation of Zinc Oxide-Nano-Particle (ZnO-NP) is a major limitation for commercial food applications. Hence a suitable alternative for ZnO-NP is highly needed for food application. Since ZnO-Bulk Particles (ZnO-BP) are food grade and there is no study on the composite prepared from ZnO-Bulk Particle-Chitosan (ZnO-BP-CH), in the present study, antimicrobial activity was assessed for ZnO-BP-CH and compared with ZnO-NP-CH. Based on the study, it was observed that in the individual form of ZnO-NP possessed significantly higher antimicrobial activity than ZnO-BP. The composite form of ZnO-NP-CH and ZnO-BP-CH possessed higher antimicrobial activity than chitosan. However, no significant difference was observed between the composite forms. Hence, ZnO-BP-CH could be recommended as a suitable alternative to ZnO-NP-CH for future studies related to chitosan with ZnO composite to avoid costly nanomaterials preparation.
- ItemFish-borne methicillin resistant Staphylococcus haemolyticus carrying atypical staphylococcal cassette chromosome mec (SCCmec) elements(Elsevier, 2021-03)Prevalence of staphylococci in fish and fish products pose high risk of foodborne diseases. As far as Staphylococcus haemolyticus as a reservoir of methicillin resistance is considered, main objective of the present study was to surveil the incidence of methicillin-resistant Staphylococcus haemolyticus (MRSH) in fishes and its genotypic characterization. 79 fish samples were collected from retail markets in three pre-decided sites in Assam. The collected fish samples were subjected to microbial analysis and as result 13 MRSH could be isolated. Susceptibility of the isolates towards various classes of antibiotics was assessed by employing BD Phoenix M50 system. Polymerase chain reaction (PCR) was performed for the molecular detection of methicillin-resistance determinant. Molecular typing of the isolates was attempted by recruiting staphylococcal cassette chromosome mec (SCCmec) and pulsed-field gel electrophoresis (PFGE). Out of 79 fish samples collected from retail markets in Assam, 13 tested positive for MRSH. These isolates showed varying levels of resistance to different classes of antibiotics such as cephalosporin (100%), lincosamide (30.76%), macrolides (30.76%), aminoglycoside (53.85%), quinolones (38.46%) and sulfonamides (61.54%). BD Phoenix M50 instrument recognized a few isolates as inducible macrolide-lincosamide-streptogramin B (iMLSb) phenotype (30.76%). Remarkably, all the isolates were reported as multi-drug resistant (MDR) as they showed resistant to ≥3 classes of antibiotics. All the studied isolates were positive for mecA gene and carrying multiple SCCmec elements. PFGE cluster analysis grouped the isolates into two major clusters and seven individual lineages. In short, the current study documented the incidence of multi-drug resistant, multiple SCCmec elements carrying S. haemolyticus in fishes. Considering the fact that S. haemolyticus contributes greatly in the dissemination of methicillin resistance owing to their extreme genome plasticity, the present study admonition the necessity of continuous monitoring the S. haemolyticus contamination in food. The study also discussed role of prudent hygienic practices in flattening the AMR curves.
- ItemPrevalence of virulent and biofilm forming ST88-IV-t2526 methicillin-resistant Staphylococcus aureus clones circulating in local retail fish markets in Assam, India(Elsevier, 2021-09)The burden of antimicrobial resistance (AMR), particularly in India has been increased alarmingly. Methicillinresistance in Staphylococcus aureus has been recognized as serious threat to the human especially if they are biofilm forming and equipped with virulence factors. In the present study monitoring of antibiotic resistant S. aureus was performed at three selected sites in Assam, India in August 2019 and February 2020. Ethnographic information was collected from the fish vendors in order to track and address potential sources of contamination. Twenty three potential methicillin-resistant S. aureus (MRSA) isolates were identified from the fish sold by the vendors and subjected to molecular characterization. The antimicrobial resistance profile of these MRSA isolates were regarded as multidrug-resistant (MDR) as they were resistant to ≥3 classes of antibiotics. The most prevalent resistance profile was; ampicillin-cefazolin-cefoxitin-gentamicin-norfloxacin-oxacillin-penicillin. Accessory gene regulators III (agr III) type MRSA (18/23, 78.26%) were found to be predominant compared to agr I type (5/ 23, 21.74%). Four isolates (17.39%) were observed to carry SCCmec-IV elements, which is a typical feature of community-associated MRSA (CA-MRSA). Two SCCmec-IV MRSA isolates were found to harbour pantonvalentine- leucocidin (PVL) toxin genes and were resistant to macrolide in addition to beta-lactams. MLST and spa typing identified all MRSA as ST88 with spa type t2526. This is the first report from India on the incidence of ST88-SCCmec-IV (ST88-IV) MRSA in a fish market and its aquatic environs. The high prevalence of a single MLST clone, ST88, suggests that this lineage has a unique survival advantage in this environment. The study discusses the contribution of hospital wastewater in the dissemination of pathogenic MRSA clones to aquatic resources and then to humans through the food chain.