Role of Natural Additives on Quality and Shelf Life Extension of Fish and Fishery Products

Fish and fishery products have drawn greater attention due to their high nutritional value owing to the presence of cheap superior quality proteins, essential fatty acids, and macro and micronutrients. But higher water content, non- protein nitrogen, and post mortem pH (6–7) in fish favor rapid spoilage by autolysis or putrefaction, and can result in health risk as well as economic loss. Moreover, the quality of fish is affected by species, harvesting season, handling and method of processing. Thus, application of food additives become necessary to maintain the shelf life, nutritional content, texture and flavor of the raw material as well as processed products. Considerable research is being done on applications of natural additives after the emergence of the concept ‘Green consumerism’ which resulted in decreased consumer preference for using synthetic food additives. In this background, this chapter will review the natural additives used for quality maintenance and shelf life extension of fish and fishery products

Genotypes and phenotypes of methicillin‐resistant staphylococci isolated from shrimp aquaculture farms

Not AvailableThe 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, 13 S. haemolyticus, 11 S. 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.Not Availabl

Antibiotic resistance profiles and molecular characteristics of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae isolated from shrimp aquaculture farms in Kerala, India

Not AvailableThis study was undertaken to evaluate the prevalence of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae in selected shrimp aquaculture farms (n = 37) in Kerala, South India and to characterize the isolates using molecular tools. Overall, a low prevalence of ESBL- producers was found in the farms, most likely due to the reduced antibiotic usage in the shrimp farming sector. Out of the 261 samples (77 shrimp and 92 each of water and sediment), 14 (5.4 % ) tested positive for ESBL-E. coli or ESBL-K. pneumoniae. A total of 32 ESBL-E. coli and 15 ESBL- K. pneumoniae were recovered from these samples. All ESBL isolates were cefotaxime-resistant with minimal inhibitory concentration (MIC) plus or minus 32 μg per ml. Of all isolates, 9 (28.1 % ) E. coli and 13 (86.7 % ) K. pneumoniae showed simultaneous resistance to tetracycline, ciprofloxacin, and trimethoprim-sulfamethoxazole. PCR analysis identified CTX-M group 1 (blaCTX–M–15) as the predominant ESBL genotype in both E. coli (23, 71.9 % ) and K. pneumoniae (15, 100 % ). Other beta-lactamase genes detected were as follows: blaTEM and blaSHV (11 K. pneumoniae), blaCTX – M group 9 (9 E. coli), and blaCMY–2 (2 E. coli). Further screening for AMR genes identified tetA and tetB (13, 40.6 % ), sul1 (11, 34.4%), sul2 (9, 28.1 % ), catA and cmlA (11, 34.4 % ), qepA and aac(6′)-Ib-cr (9, 28.1 % ) and strAB and aadA1 (2, 6.3%) in E. coli, and qnrB (13, 86.7%), qnrS (3, 20%), oqxB (13, 86.7%), tetA (13, 86.7 % ), and sul2 (13, 86.7 % ) in K. pneumoniae isolates. Phylogenetic groups identified among E. coli isolates included B1 (4, 12.5 % ), B2 (6, 18.8 % ), C (10, 31.3%), D (3, 9.4 % ), and E (9, 28.1 % ). PCR-based replicon typing (PBRT) showed the predominance of IncFIA and IncFIB plasmids in E. coli; however, in K. pneumoniae, the major replicon type detected was IncHI1. Invariably, all isolates of K. pneumoniae harbored virulence-associated genes viz., iutA, entB, and mrkD. Epidemiological typing by pulsed-field gel electrophoresis (PFGE) revealed that E. coli isolates recovered from different farms were genetically unrelated, whereas isolates of K. pneumoniae showed considerable genetic relatedness. In conclusion, our findings provide evidence that shrimp aquaculture environments can act as reservoirs of multi-drug resistant E. coli and K. pneumoniae.Not Availabl

The CRISPR/Cas system as an antimicrobial resistance strategy in aquatic ecosystems

With the growing population, demand for food has dramatically increased, and fisheries, including aquaculture, are expected to play an essential role in sustaining demand with adequate quantities of protein and essential vitamin supplements, employment generation, and GDP growth. Unfortunately, the incidence of emerging/re-emerging AMR pathogens annually occurs because of anthropogenic activities and the frequent use of antibiotics in aquaculture. These AMR pathogens include the WHO's top 6 prioritized ESKAPE pathogens (nosocomial pathogens: Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.), extended-spectrum beta lactases (ESBLs) and carbapenemase-producing E. coli, which pose major challenges to the biomagnification of both nonnative and native antibiotic-resistant bacteria in capture and cultured fishes. Although implementing the rational use of antibiotics represents a promising mitigation measure, this approach is practically impossible due to the lack of awareness among farmers about the interplay between antimicrobial use and the emergence of antimicrobial resistance (AMR). Nevertheless, to eradicate these 'superbugs,' CRISPR/Cas (clustered regularly interspersed short palindromic repeats/CRISPR associate protein) has turned out to be a novel approach owing to its ability to perform precise site-directed targeting/knockdown/reversal of specific antimicrobial resistance genes in vitro and to distinguish AMR-resistant bacteria from a plethora of commensal aquatic bacteria. Along with highlighting the importance of virulent multidrug resistance genes in bacteria, this article aims to provide a holistic picture of CRISPR/Cas9-mediated genome editing for combating antimicrobial-resistant bacteria isolated from various aquaculture and marine systems, as well as insights into different types of CRISPR/Cas systems, delivery methods, and challenges associated with developing CRISPR/Cas9 antimicrobial agents.</p

Edible mushrooms as functional ingredients for development of healthier and more sustainable muscle foods: a flexitarian approach

Consumers are increasingly interested in nutritious, safe and healthy muscle food products with reduced salt and fat that benefit their well-being. Hence, food processors are constantly in search of natural bioactive ingredients that offer health benefits beyond their nutritive values without affecting the quality of the products. Mushrooms are considered as next-generation healthy food components. Owing to their low content of fat, high-quality proteins, dietary fibre and the presence of nutraceuticals, they are ideally preferred in formulation of low-caloric functional foods. There is a growing trend to fortify muscle food with edible mushrooms to harness their goodness in terms of nutritive, bioactive and therapeutic values. The incorporation of mushrooms in muscle foods assumes significance, as it is favourably accepted by consumers because of its fibrous structure that mimics the texture with meat analogues offering unique taste and umami flavour. This review outlines the current knowledge in the literature about the nutritional richness, functional bioactive compounds and medicinal values of mushrooms offering various health benefits. Furthermore, the effects of functional ingredients of mushrooms in improving the quality and sensory attributes of nutritionally superior and next-generation healthier muscle food products are also highlighted in this paper.Axencia Galega de Innovación | Ref. IN607A2019 / 0