Identification and Antimicrobial Resistance of Bacteria Isolated from Probiotic Products Used in Shrimp Culture

Identification of differentially expressed genes and metabolism signaling pathway in the spleen of broilers supplemented with probiotic Bacillus spp

Probiotics are essential in the body's nutrients, improving the ratio of meat to meat, immune response, and preventing diseases. In this study, RNA-sequencing (RNA-seq) was used to identify the differentially expressed genes (DEGs), enriched related pathways, and Gene Ontology (GO) terms among blank negative control (NC), supplemented with Bacillus spp. (BS) and commercial probiotic (PC) groups after a 42-day fed supplementation. The results showed that 2005, 1356, and 2189 DEGs were significantly altered in BS vs. NC, PC vs NC, and BS vs PC groups, respectively. On the other hand, 9 DEGs were further validated by qRT-PCR, indicating that the qRT-PCR and RNA-Seq results were more consistent. Therefore, the GO and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses of DEGs showed that the DEGs were mainly enriched to metabolism signalling pathways (alpha-linolenic acid metabolism, linoleic acid metabolism, tryptophan metabolism, tyrosine metabolism, ether lipid metabolism, and metabolic pathway, etc) and immune response pathways (cytokine-cytokine receptor interaction, MAPK signalling pathway, and intestinal immune network for IgA production, neuroactive ligand-receptor interaction etc). These results will provide a better understanding of the role of probiotics in chicken development and provide basic information on the genetic development of chickens.

Potential probiotic Lactobacillus delbrueckii subsp. lactis KUMS-Y33 suppresses adipogenesis and promotes osteogenesis in human adipose-derived mesenchymal stem cell

Today, probiotics are considered to be living microorganisms whose consumption has a certain number of beneficial effects on the consumer. The present study aimed to investigate the effect of a new probiotic extract (Lactobacillus delbrueckii subsp. lactis KUMS Y33) on the differentiation process of human adipose-derived stem cells (hADSCs) into adipocytes and osteocytes and, as a result, clarify its role in the prevention and treatment of bone age disease. Several bacteria were isolated from traditional yogurt. They were evaluated to characterize the probiotic's activity. Then, the isolated hADSCs were treated with the probiotic extract, and then osteogenesis and adipogenesis were induced. To evaluate the differentiation process, oil red O and alizarin red staining, a triglyceride content assay, an alkaline phosphatase (ALP) activity assay, as well as real-time PCR and western blot analysis of osteocyte- and adipocyte-specific genes, were performed. Ultimately, the new strain was sequenced and registered on NBCI. In the probiotic-treated group, the triglyceride content and the gene expression and protein levels of C/EBP-α and PPAR-γ2 (adipocyte-specific markers) were significantly decreased compared to the control group (P < 0.05), indicating an inhibited adipogenesis process. Furthermore, the probiotic extract caused a significant increase in the ALP activity, the expression levels of RUNX2 and osteocalcin, and the protein levels of collagen I and FGF-23 (osteocyte-specific markers) in comparison to the control group (P < 0.05), indicating an enhanced osteogenesis process. According to the results of the present study, the probiotic extract inhibits adipogenesis and significantly increases osteogenesis, suggesting a positive role in the prevention and treatment of osteoporosis and opening a new aspect for future in-vivo study.

Prevalence and antimicrobial resistance profiles of Vibrio spp. and Enterococcus spp. in retail shrimp in Northern California

Shrimp is one of the most consumed seafood products globally. Antimicrobial drugs play an integral role in disease mitigation in aquaculture settings, but their prevalent use raises public health concerns on the emergence and spread of antimicrobial resistant microorganisms. Vibrio spp., as the most common causative agents of seafood-borne infections in humans, and Enterococcus spp., as an indicator organism, are focal bacteria of interest for the monitoring of antimicrobial resistance (AMR) in seafood. In this study, 400 samples of retail shrimp were collected from randomly selected grocery stores in the Greater Sacramento, California, area between September 2019 and June 2020. The prevalence of Vibrio spp. and Enterococcus spp. was 60.25% (241/400) and 89.75% (359/400), respectively. Subsamples of Vibrio (n = 110) and Enterococcus (n = 110) isolates were subjected to antimicrobial susceptibility testing (AST). Vibrio isolates had high phenotypic resistance to ampicillin (52/110, 47.27%) and cefoxitin (39/110, 35.45%). Enterococcus were most frequently resistant to lincomycin (106/110, 96.36%), quinupristin-dalfopristin (96/110, 87.27%), ciprofloxacin (93/110, 84.55%), linezolid (86/110, 78.18%), and erythromycin (58/110, 52.73%). For both Vibrio and Enterococcus, no significant associations were observed between multidrug resistance (MDR, resistance to ≥3 drug classes) in isolates from farm raised and wild caught shrimp (p > 0.05) and in isolates of domestic and imported origin (p > 0.05). Whole genome sequencing (WGS) of a subset of Vibrio isolates (n = 42) speciated isolates as primarily V. metschnikovii (24/42; 57.14%) and V. parahaemolyticus (12/42; 28.57%), and detected 27 unique antimicrobial resistance genes (ARGs) across these isolates, most commonly qnrVC6 (19.05%, 8/42), dfrA31 (11.90%, 5/42), dfrA6 (9.5%, 4/42), qnrVC1 (9.5%, 4/42). Additionally, WGS predicted phenotypic resistance in Vibrio isolates with an overall sensitivity of 11.54% and specificity of 96.05%. This study provides insights on the prevalence and distribution of AMR in Vibrio spp. and Enterococcus spp. from retail shrimp in California which are important for food safety and public health and exemplifies the value of surveillance in monitoring the spread of AMR and its genetic determinants.

Evaluation of a synbiotic formulation for water remediation in a shrimp pond

In recent years, the use of probiotic bacteria has attracted the interest of the marine shrimp farming industry. However, there are certain limitations pertaining to the practical application of many commercially available probiotics. Here, a thoroughly screened optimal consortium of three indigenous sulfur probiotics was tested for antibiotic susceptibility and was found to be safe, with each culture being sensitive to all the tested antibiotics. Further, de-potash vinasse (DPV), an environmental hazard, was tested for its prebiotic potential, and its 1% (w/v) concentration was found to be effective for long-term viability (> 66 days) of the probiotic cultures and safe for Artemia. The synbiotic formulation was tested first in a lab-scale microcosm setup successfully and subsequently tried on a shrimp farm; it was observed that the product was congruent to the efficiency of a commercial probiotic regarding almost all physicochemical parameters, sulfide, nitrate-N, nitrite-N, phytoplankton sustenance, Pseudomonas count, coliform count, and heterotrophic count. In addition, it was significantly efficient in maintaining pH, reducing ammonia-N and phosphate-P, Vibrio and Aeromonas count, and a net increase in the yield of shrimp biomass by 625 kg, thus proving to be a better alternative than one of the already available remediation methods.

Function-based classification of hazardous biological sequences: Demonstration of a new paradigm for biohazard assessments

Bioengineering applies analytical and engineering principles to identify functional biological building blocks for biotechnology applications. While these building blocks are leveraged to improve the human condition, the lack of simplistic, machine-readable definition of biohazards at the function level is creating a gap for biosafety practices. More specifically, traditional safety practices focus on the biohazards of known pathogens at the organism-level and may not accurately consider novel biodesigns with engineered functionalities at the genetic component-level. This gap is motivating the need for a paradigm shift from organism-centric procedures to function-centric biohazard identification and classification practices. To address this challenge, we present a novel methodology for classifying biohazards at the individual sequence level, which we then compiled to distinguish the biohazardous property of pathogenicity at the whole genome level. Our methodology is rooted in compilation of hazardous functions, defined as a set of sequences and associated metadata that describe coarse-level functions associated with pathogens (e.g., adherence, immune subversion). We demonstrate that the resulting database can be used to develop hazardous “fingerprints” based on the functional metadata categories. We verified that these hazardous functions are found at higher levels in pathogens compared to non-pathogens, and hierarchical clustering of the fingerprints can distinguish between these two groups. The methodology presented here defines the hazardous functions associated with bioengineering functional building blocks at the sequence level, which provide a foundational framework for classifying biological hazards at the organism level, thus leading to the improvement and standardization of current biosecurity and biosafety practices.

The prevalence, antibiotic resistance and multilocus sequence typing of colistin-resistant bacteria isolated from Penaeus vannamei farms in earthen ponds and HDPE film-lined ponds in China

The aquaculture environment, especially the culture ponds and aquaculture products, is considered to be an important reservoir of colistin resistance genes. However, systematic investigations of colistin resistance in Penaeus vannamei farming in different culture modes are scarce. In this study, a total of 93 non-duplicated samples were collected from P. vannamei farms in five cities in China from 2019 to 2021. The prevalence, antibiotic resistance and multilocus sequence typing (MLST) of colistin-resistant bacteria were measured and analysed. The results showed that among the 1601 isolates in P. vannamei and its environmental samples, the pollution of colistin-resistant bacteria was serious (the overall prevalence was 37.3% and 28.8%, respectively), regardless of the earthen pond or high-density polyethylene (HDPE) film-lined pond. Among 533 isolates, the prevalence of mobile colistin resistance (mcr) genes, mcr-1, was the highest (60%, 320/533), followed by mcr-4 (1.5%, 8/533), mcr-8 (0.9%, 5/533), mcr-10 (0.6%, 3/533) and mcr-7 (0.4%, 2/533). The prevalence of mcr-1 in earthen ponds was significantly higher than that in HDPE film-lined ponds (67.5% vs. 49.1%, p < .001). The dominant strain carrying mcr-1 was Bacillus spp. (54.1%, 173/320), followed by Enterobacter spp. (8.1%, 26/320), Staphylococcus spp. (6.3%, 20/320) and Aeromonas spp. (5.3%, 17/320). The antibiotic resistance profiles of 173 Bacillus spp. varied among different sampling locations and culture types. These isolates were highly resistant to cefepime, ceftriaxone, trimethoprim-sulfamethoxazole and ceftiofur (>45%), and multidrug-resistant isolates were common (62.4%, 108/173). Sequence type (ST) 26 (37/66, 56%) was found to be the most prevalent ST in mcr-1-positive Bacillus cereus isolated from the aquaculture environment. In summary, our study pointed out that it is necessary to continuously monitor antibiotic usage and its residues regardless of the pond types, especially with regard to critical drugs such as colistin.

Antimicrobial resistance determinants in silage

Animal products may play a role in developing and spreading antimicrobial resistance in several ways. On the one hand, residues of antibiotics not adequately used in animal farming can enter the human body via food. However, resistant bacteria may also be present in animal products, which can transfer the antimicrobial resistance genes (ARG) to the bacteria in the consumer’s body by horizontal gene transfer. As previous studies have shown that fermented foods have a meaningful ARG content, it is indicated that such genes may also be present in silage used as mass feed in the cattle sector. In our study, we aspired to answer what ARGs occur in silage and what mobility characteristics they have? For this purpose, we have analyzed bioinformatically 52 freely available deep sequenced silage samples from shotgun metagenome next-generation sequencing. A total of 16 perfect matched ARGs occurred 54 times in the samples. More than half of these ARGs are mobile because they can be linked to integrative mobile genetic elements, prophages or plasmids. Our results point to a neglected but substantial ARG source in the food chain.

Antibiotic resistance of culturable heterotrophic bacteria isolated from shrimp (Penaeus vannamei) aquaculture ponds

Shrimp aquaculture is one of the fastest growing food-producing avenues, where antibiotics usage has become an issue of great concern due to the development of antimicrobial resistance in bacteria. A total of 2304 bacterial isolates from 192 samples (sediment, water, shrimp, and source water) from Andhra Pradesh, India were screened. Antibiotic resistance of bacterial isolates was highest for oxytetracycline (23.4%) followed by erythromycin (12.7%), co-trimoxazole (10%) ciprofloxacin (9.6%), and chloramphenicol (6%), of which 11.9% isolates were multi-drug resistant. Bacterial isolates from shrimp (26.7%), water (23.9%), and sediment (19.6%) samples exhibited more resistance (p ≤ 0.05) towards oxytetracycline. Higher antibacterial resistance was observed from samples of southern Andhra Pradesh (locations L6 and L7). Gram negative bacteria were more prevalent (64%) and showed significantly (p ≤ 0.01) higher resistance. This study indicated the wider distribution of antibiotic-resistant bacteria in shrimp aquaculture ponds with potential risk to humans and the environment.

Bacillus spore-forming probiotics: benefits with concerns?

Representatives of the genus Bacillus are multifunctional microorganisms with a broad range of applications in both traditional fermentation and modern biotechnological processes. Bacillus spp. has several beneficial properties. They serve as starter cultures for various traditional fermented foods and are important biotechnological producers of enzymes, antibiotics, and bioactive peptides. They are also used as probiotics for humans, in veterinary medicine, and as feed additives for animals of agricultural importance. The beneficial effects of bacilli are well-reported and broadly acknowledged. However, with a better understanding of their positive role, many questions have been raised regarding their safety and the relevance of spore formation in the practical application of this group of microorganisms. What is the role of Bacillus spp. in the human microbial consortium? When and why did they start colonizing the gastrointestinal tract (GIT) of humans and other animals? Can spore-forming probiotics be considered as truly beneficial organisms, or should they still be approached with caution and regarded as "benefits with concerns"? In this review, we not only hope to answer the above questions but to expand the scope of the conversation surrounding bacilli probiotics.

Impact of spent engine oil contamination on the antibiotic resistome of a tropical agricultural soil

Profiling of hydrocarbon-contaminated soils for antibiotic resistance genes (ARGs) is becoming increasingly important due to emerging realities of their preponderance in hydrocarbon-inundated matrices. In this study, the antibiotic resistome of an agricultural soil (1S) and agricultural soil contaminated with spent engine oil (AB1) were evaluated via functional annotation of the open reading frames (ORFs) of their metagenomes using the comprehensive antibiotic database (CARD) and KEGG KofamKOALA. CARD analysis of AB1 metagenome revealed the detection of 24 AMR (antimicrobial resistance) gene families, 66 ARGs, and the preponderance (69.7%) of ARGs responsible for antibiotic efflux in AB1 metagenome. CARD analysis of 1S metagenome revealed four AMR gene families and five ARGs. Functional annotation of the two metagenomes using KofamKOALA showed 171 ARGs in AB1 and 29 ARGs in 1S, respectively. Majority of the detected ARGs in AB1 (121; 70.8%) and 1S (16; 55.2%) using KofamKOALA are responsible for antibiotic efflux while ARGs for other resistance mechanisms were also detected. All the five major antibiotic efflux pump systems were detected in AB1 metagenome, though majority of the ARGs for antibiotic efflux belong to the RND (resistance-nodulation-cell division) and MFS (major facilitator superfamily) efflux systems. Significant differences observed in the ARGs recovered from 1S and AB1 metagenomes were statistically validated (P < 0.05). SEO contamination is believed to be responsible for ARGs increase in AB1 metagenome via mechanisms of cross-resistance especially with efflux pumps. The detection of these ARGs is of great public health concern in this era of multidrug resistant isolates resurgence.

Synergistic Antimicrobial Effect of a Seaweed-Probiotic Blend Against Acute Hepatopancreatic Necrosis Disease (AHPND)-Causing Vibrio parahaemolyticus

The outbreak of acute hepatopancreatic necrosis disease (AHPND) has caused great economic losses to the shrimp culture sector. However, the use of antibiotics to fight this disease has resulted in negative impacts on human health and the environment. Thus, the use of natural alternatives to antibiotics may be a better solution. In this study, four Bacillus species obtained from the guts of shrimps (Fenneropenaeus penicillatus and Penaeus monodon) showed antimicrobial activity against the AHPND-causing Vibrio parahaemolyticus strain 3HP using the cross-streaking and agar spot methods. Two of the Bacillus isolates, B2 and BT, also showed good probiotic properties, exhibiting tolerance to bile, good adhesion to shrimp mucus, non-hemolytic, susceptibility to antibiotics and being safe towards hosts. Moreover, a seaweed-probiotic blend (a combination of Bacillus B2 and 20 mg/ml of the red seaweed Gracilaria sp.) exhibited synergistic in vitro inhibition against V. parahaemolyticus strain 3HP, with an observed inhibition zone of 5.0 mm. The broth co-culture experiment results further indicated that the seaweed-probiotic blend inhibited V. parahaemolyticus through competitive exclusion. The in vivo challenge trials also confirmed that this seaweed-probiotic blend significantly reduced the mortality of shrimps post-challenge with the AHPND-causing V. parahaemolyticus strain 3HP (p < 0.05) compared to the negative control (mortality rate = 13.88% vs 72.19%). Thus, this seaweed-probiotic blend may serve as an alternative to antibiotics in controlling the outbreak of AHPND.

Tarkhineh as a new microencapsulation matrix improves the quality and sensory characteristics of probiotic Lactococcus lactis KUMS-T18 enriched potato chips

In the present study, probiotic potato chips containing a newly isolated probiotic Lactococcus lactis KUMS-T18 strain were produced by using a simple spraying method and then enhancing the stability, survival rate, and sensory characteristics of product during storage at 4 °C and 25 °C was examined for four months. Based on the results, Lactococcus lactis KUMS-T18 isolated from traditional Tarkhineh as a safe strain had high tolerance to low pH and high bile salt, anti-pathogenic activity, hydrophobicity, adhesion to human epithelial cells, auto- and co-aggregation, cholesterol assimilation and antibiotic susceptibility. Meanwhile, by micro-coating the probiotic cells in Tarkhineh formulations, elliptical to spherical shape (460-740 µm) probiotic drops were produced. The results revealed that potato chips produced with turmeric and plain Tarkhineh during storage at 4 °C, had excellent protection abilities for probiotic cells with about 4.52 and 3.46 log decreases in CFU/g respectively. On the other hand, probiotic potato chips, compared to non-probiotic and commercial potato chips, showed the criteria of probiotic products such as excellent quality and superior sensory characteristics. In summary, this study proved that probiotic Lactococcus lactis KUMS-T18 strain covered by Tarkhineh formulations as protective matrix has high potential to be used in the production of probiotic potato chips.

Application of Tarkhineh Fermented Product to Produce Potato Chips With Strong Probiotic Properties, High Shelf-Life, and Desirable Sensory Characteristics

The application of Tarkhineh texture to protect probiotics in potato chips has been investigated as the main goal in this paper. In this study, the probiotic assessments, morphological characteristics, sensory evaluation, and survival rates of the covered probiotic cells with Tarkhineh in potato chips during storage time were assessed. Based on results, T34 isolated from traditional Tarkhineh as a safe strain had a high tolerance to low pH and bile salt conditions, displayed acceptable anti-pathogenic activities, and also showed desirable antibiotic susceptibility. Two types of Tarkhineh formulations (plain Tarkhineh and turmeric Tarkhineh) were applied using a simple spraying method for covering T34 cells in potato chips. All formulations showed elliptical to spherical (480-770 μm) shape probiotic drops. Storage stability results revealed that T34 cells mixed with turmeric and plain Tarkhineh during 4 months of storage at 4°C displayed excellent protection abilities with about 3.70 and 2.85 log decreases in CFU/g respectively. Additionally, probiotic potato chips compared to non-probiotic and commercial potato chips, exhibited probiotic product criteria such as excellent quality and superior sensory properties during storage time. In conclusion, Tarkhineh showed high potential as a protective matrix for probiotic cells in potato chips.

A critical review of antibiotic resistance in probiotic bacteria

Probiotics are defined as live microorganisms that, when administered in adequate amounts, confer a health benefit upon the host. At present, probiotics are gaining popularity worldwide and are widely used in food and medicine. Consumption of probiotics is increasing with further in-depth research on the relationship between intestinal flora and host health. Most people pay more attention to the function of probiotics but ignore their potential risks, such as infection and antibiotic resistance transfer to pathogenic microbes. Physiological functions, effects and mechanisms of action of probiotics were covered in this review, as well as the antibiotic resistance phenotypes, mechanisms and genes found in probiotics. Typical cases of antibiotic resistance of probiotics were also highlighted, as well as the potential risks (including pathogenicity, infectivity and excessive immune response) and corresponding strategies (dosage, formulation, and administration route). This timely study provides an avenue for further research, development and application of probiotics.

Evaluating antimicrobial resistance in the global shrimp industry

Antimicrobial resistance (AMR) is a growing threat to global public health, and the overuse of antibiotics in animals has been identified as a major risk factor. With high levels of international trade and direct connectivity to the aquatic environment, shrimp aquaculture may play a role in global AMR dissemination. The vast majority of shrimp production occurs in low- and middle-income countries, where antibiotic quality and usage is widely unregulated, and where the integration of aquaculture with family livelihoods offers many opportunities for human, animal and environmental bacteria to come into close contact. Furthermore, in shrimp growing areas, untreated waste is often directly eliminated into local water sources. These risks are very different to many other major internationally-traded aquaculture commodities, such as salmon, which is produced in higher income countries where there are greater levels of regulation and well-established management practices. Assessing the true scale of the risk of AMR dissemination in the shrimp industry is a considerable challenge, not least because obtaining reliable data on antibiotic usage is very difficult. Combating the risks associated with AMR dissemination is also challenging due to the increasing trend towards intensification and its associated disease burden, and because many farmers currently have no alternatives to antibiotics for preventing crop failure. In this review, we critically assess the potential risks the shrimp industry poses to AMR dissemination. We also discuss some of the possible risk mitigation strategies that could be considered by the shrimp industry as it strives for a more sustainable future in production.

Screening of bacterial strains from the gut of Pacific White Shrimp (Litopenaeus vannamei) and their efficiencies in improving the fermentation of soybean meal

Microbial fermentation is an efficient, economical and eco-friendly approach to overcome the limitations in soybean meal replacement of fish meal in aquaculture. However, little research focused on the development of shrimp-derived strains for fermentation of SBM. In this study, Bacillus sanfensis (SQVG18) and Bacillus stratosphericus (SQVG22) were screened from shrimp intestine for fermentation according to the activities of protease, cellulase and phytase. The optimized fermentation conditions of SQVG18 and SQVG22 were as follow: fermentation temperature (40°C vs 35°C), fermentation time (48h both), inoculation amount [4% both (v/m)], solid-liquid ratio [1:1.2 vs 1:1 (g/ml)]. After 48 h fermentation, SQVG18 and SQVG22 increased crude protein content by 6.93% and 5.95%, respectively; degraded most of macromolecular proteins to micromolecular proteins (< 20 kDa); improved amino acids profiles, like lysine and methionine in particular; significantly decreased the anti-nutritional factors such as trypsin inhibitor, glycinin and β-conglycinin (P < 0.05). In addition, both strains were observed no hemolytic activity, less antibiotic resistance genes and definite inhibition to common shrimp pathogens of Vibrio alginolyticus sp. and Vibrio parahaemolyticus sp. These results indicated that both strains could improve nutrition values of soybean meal effectively and have potential applications in shrimp culture.

Frequency of hemolysin BL and non-hemolytic enterotoxin complex genes of Bacillus cereus in raw and cooked meat samples in Zanjan, Iran

Food safety has emerged as an important global issue with international trade and public health implications. Bacillus cereus is an important cause of food poisoning worldwide. A total of 200 individual meat samples were collected from meat retail outlets and restaurants and investigated the frequency of B. cereus and hemolysin BL (Hbl), non-hemolytic enterotoxin (Nhe) complex genes. The meat samples were immediately homogenized and cultured on Bacillus cereus selective agar and subjected for confirmatory biochemical tests and molecular detection of gyrB, hblA, hblC, hblD, nheA, nheB and nheC genes. A total of 29 (14.5 %) meat samples were positive for the presence of B. cereus. The frequency of B. cereus in raw meat (14.1 %) was similar to cooked beef samples (15 %) (P >  0.05). Twenty six (89.6 %) isolates carried at least one or more enterotoxin genes. We found nheA (58.6 %) and hblD (51.7 %) genes with higher frequency than others. Hemolysin BL complex genes were found in lower frequency than Nhe complex (P >  0.05). Detection of enterotoxigenic B. cereus in meat samples shows a probable risk for public health. Therefore, the reliable molecular methods for monitoring of potentially pathogenic B. cereus are strongly recommended for the routine food examination.

TiO2 and Au-TiO2 Nanomaterials for Rapid Photocatalytic Degradation of Antibiotic Residues in Aquaculture Wastewater

Antibiotic residues in aquaculture wastewater are considered as an emerging environmental problem, as they are not efficiently removed in wastewater treatment plants. To address this issue, we fabricated TiO₂ nanotube arrays (TNAs), TiO₂ nanowires on nanotube arrays (TNWs/TNAs), Au nanoparticle (NP)-decorated-TNAs, and TNWs/TNAs, which were applied for assessing the photocatalytic degradation of eight antibiotics, simultaneously. The TNAs and TNWs/TNAs were synthesized by anodization using an aqueous NH₄F/ethylene glycol solution. Au NPs were synthesized by chemical reduction method, and used to decorate on TNAs and TNWs/TNAs. All the TiO₂ nanostructures exhibited anatase phase and well-defined morphology. The photocatalytic performance of TNAs, TNWs/TNAs, Au-TNAs and Au-TNWs/TNAs was studied by monitoring the degradation of amoxicillin, ampicillin, doxycycline, oxytetracycline, lincomycin, vancomycin, sulfamethazine, and sulfamethoxazole under ultraviolet (UV)-visible (VIS), or VIS illumination by LC-MS/MS method. All the four kinds of nanomaterials degraded the antibiotics effectively and rapidly, in which most antibiotics were removed completely after 20 min treatment. The Au-TNWs/TNAs exhibited the highest photocatalytic activity in degradation of the eight antibiotics. For example, reaction rate constants of Au-TNWs/TNAs for degradation of lincomycin reached 0.26 min⁻¹ and 0.096 min⁻¹ under UV-VIS and VIS irradiation, respectively; and they were even higher for the other antibiotics. The excellent photocatalytic activity of Au-TNWs/TNAs was attributed to the synergistic effects of: (1) The larger surface area of TNWs/TNAs as compared to TNAs, and (2) surface plasmonic effect in Au NPs to enhance the visible light harvesting.

Selection of carbohydrate-active probiotics from the gut of carnivorous fish fed plant-based diets

The gastrointestinal microbiota plays a critical role on host health and metabolism. This is particularly important in teleost nutrition, because fish do not possess some of the necessary enzymes to cope with the dietary challenges of aquaculture production. A main difficulty within fish nutrition is its dependence on fish meal, an unsustainable commodity and a source of organic pollutants. The most obvious sustainable alternatives to fish meal are plant feedstuffs, but their nutritive value is limited by the presence of high levels of non-starch polysaccharides (NSP), which are not metabolized by fish. The composition of fish-gut microbial communities have been demonstrated to adapt when the host is fed different ingredients. Thus, we hypothesized that a selective pressure of plant-based diets on fish gut microbiota, could be a beneficial strategy for an enrichment of bacteria with a secretome able to mobilize dietary NSP. By targeting bacterial sporulating isolates with diverse carbohydrase activities from the gut of European sea bass, we have obtained isolates with high probiotic potential. By inferring the adaptive fitness to the fish gut and the amenability to industrial processing, we identified the best two candidates to become industrially valuable probiotics. This potential was confirmed in vivo, since one of the select isolates lead to a better growth and feed utilization efficiency in fish fed probiotic-supplemented plant-based diets, thus contributing for sustainable and more cost-effective aquaculture practices.

Properties of Probiotics Kocuria SM1 and Rhodococcus SM2 Isolated from Fish Guts

This study characterized probiotics Kocuria SM1 and Rhodococcus SM2, which were recovered from the intestinal microbiota of rainbow trout (Oncorhynchus mykiss, Walbaum). The cultures were Gram-positive, non-motile, catalase-positive and oxidase-negative cocci or rods. Cell multiplication of SM1 and SM2 was observed at 4-37 °C (45 °C for SM1), in 0-20% (w/v) NaCl and at pH 2-11. The viability was not affected when exposed to pepsin at pH 2.0 and 3.0, and pancreatin at pH 8.0. Neither isolates were chrome azurol S-positive for siderophore production. Of the 19 common enzymes analysed using the API-ZYM system, only 8 were evident in the culture of SM1 compared to 11 enzymes for SM2. The secondary metabolites of both probiotics were inhibitory to Acinetobacter baumannii, Vibrio anguillarum and V. ordalii; SM2 inhibited Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Staphylococcus aureus. SM2 was resistant to penicillin and sulphatriad, out of six antimicrobial agents; SM1 was resistant to sulphatriad. These results suggest that Kocuria SM1 and Rhodococcus SM2 are able to grow over a wide range of temperature, salinity and pH, including in conditions that mimic the gastrointestinal environment of fish and produce extracellular enzymes that may have a role in the host digestive processes. Importantly, Rhodococcus SM2 displays a high degree of bacteriocinogenic potential against multi-drug-resistant human pathogens that have never been documented among the gut microbiota of fish.

Molecular Characterization and Antibiotic Resistance of Foodborne Pathogens in Street-Vended Ready-to-Eat Meat Sold in South Africa

ABSTRACT

The consumption of food contaminated with microbial populations remains a key route of foodborne infection in developing countries and creates a serious public health burden. This study aimed at identifying foodborne pathogens and their antibiotic resistance profiles in ready-to-eat meat sold in public eateries in the Johannesburg area. A total of 115 samples were examined for the incidence of bacteria pathogens and their antibiotic resistance profiles against commonly used antibiotics (ampicillin, tetracycline, chloramphenicol, erythromycin, ciprofloxacin, streptomycin, and sulphonamides) using the molecular and the disc diffusion methods. Fifteen bacteria species were detected in the samples. Staphylococcus aureus had the highest prevalence (25%), and 53.33% of the isolates exhibited multidrug resistance to the antibiotics tested. Among the isolated bacteria, S. aureus; was resistant to at least six antimicrobial agents, whereas 100% of S. aureus,Enterococcus faecalis, and Planomicrobium glaciei were resistant to streptomycin, ciprofloxacin, and chloramphenicol, respectively. This study revealed that a wide diversity of bacteria species contaminate meat sold on the street, which indicates that consumers of ready-to-eat meat sold in public eateries are at risk of food poisoning. Hence, strict intervention strategies should be put in place by government agencies to reduce the menace of food poisoning in the country.

HIGHLIGHTS

RTE meats were analyzed for microbial contamination. Foodborne pathogens were detected in the meat samples. Antibiotic resistance profiles were tested. RTE meats contain foodborne pathogens, and isolates exhibited antibiotic resistance. Consumers of RTE meat in the Johannesburg CBD are at risk of food poisoning.

Meropenem-resistant bacteria in hospital effluents in Seoul, Korea

This study aimed to understand the prevalence, diversity, antibiotic resistance, β-lactamase gene types, and possibility of environmental survival of meropenem-resistant bacteria present in hospital effluents in Seoul, Korea. Water sampling was performed at five general hospitals in Seoul, Korea, in January 2017. Water samples were plated in triplicate on tryptic soy agar plates with 16 mg/L meropenem. Meropenem-resistant bacteria were selected and subjected to 16S rRNA analysis for species determination and PCR for identification of β-lactamase gene types. Resistant bacteria were cultured in sterilized surface water. Meropenem-resistant bacteria exhibited resistance to more than 12 antibiotics and possessed several β-lactamase genes, such as those encoding OXT-M, NDM-1, AmpC, and OXA. They were able to multiply and survive in sterilized surface water for up to 60 days. Multidrug-resistant bacteria represent an environmental health risk, as they can survive in the environment for an extended period of time. Therefore, these bacteria should be monitored before discharge.

Antimicrobial Susceptibility Testing and Tentative Epidemiological Cutoff Values for Five Bacillus Species Relevant for Use as Animal Feed Additives or for Plant Protection

Bacillus megaterium (n = 29), Bacillus velezensis (n = 26), Bacillus amyloliquefaciens (n = 6), Bacillus paralicheniformis (n = 28), and Bacillus licheniformis (n = 35) strains from different sources, origins, and time periods were tested for the MICs for nine antimicrobial agents by the CLSI-recommended method (Mueller-Hinton broth, 35°C, for 18 to 20 h), as well as with a modified CLSI method (Iso-Sensitest [IST] broth, 37°C [35°C for B. megaterium], 24 h). This allows a proposal of species-specific epidemiological cutoff values (ECOFFs) for the interpretation of antimicrobial resistance in these species. MICs determined by the modified CLSI method were 2- to 16-fold higher than with the CLSI-recommended method for several antimicrobials. The MIC distributions differed between species for five of the nine antimicrobials. Consequently, use of the modified CLSI method and interpretation of resistance by use of species-specific ECOFFs is recommended. The genome sequences of all strains were determined and used for screening for resistance genes against the ResFinder database and for multilocus sequence typing. A putative chloramphenicol acetyltransferase (cat) gene was found in one B. megaterium strain with an elevated chloramphenicol MIC compared to the other B. megaterium strains. In B. velezensis and B. amyloliquefaciens, a putative tetracycline efflux gene, tet(L), was found in all strains (n = 27) with reduced tetracycline susceptibility but was absent in susceptible strains. All B. paralicheniformis and 23% of B. licheniformis strains had elevated MICs for erythromycin and harbored ermD The presence of these resistance genes follows taxonomy suggesting they may be intrinsic rather than horizontally acquired. Reduced susceptibility to chloramphenicol, streptomycin, and clindamycin could not be explained in all species.IMPORTANCE When commercializing bacterial strains, like Bacillus spp., for feed applications or plant bioprotection, it is required that the strains are free of acquired antimicrobial resistance genes that could potentially spread to pathogenic bacteria, thereby adding to the pool of resistance genes that may cause treatment failures in humans or animals. Conversely, if antimicrobial resistance is intrinsic to a bacterial species, the risk of spreading horizontally to other bacteria is considered very low. Reliable susceptibility test methods and interpretation criteria at the species level are needed to accurately assess antimicrobial resistance levels. In the present study, tentative ECOFFs for five Bacillus species were determined, and the results showed that the variation in MICs followed the respective species. Moreover, putative resistance genes, which were detected by whole-genome sequencing and suggested to be intrinsic rather that acquired, could explain the resistance phenotypes in most cases.

An assessment of health management practices and occupational health hazards in tiger shrimp (Penaeus monodon) and freshwater prawn (Macrobrachium rosenbergii) aquaculture in Bangladesh

Diseases have been recognized as the major obstacle to the shrimp (Penaeus monodon) and prawn (Macrobrachium rosenbergii) aquaculture production in Bangladesh. This study provides an assessment of shrimp and prawn diseases/syndromes, health management practices, and occupational health hazards associated with the handling of chemical and biological products to prevent and treat shrimp and prawn diseases. A survey was conducted using a semi-structured questionnaire with 380 shrimp and prawn farmers in the southwest of Bangladesh during February and June of 2016. The farms were categorized on the basis of the three cropping patterns: shrimp polyculture, prawn polyculture, and shrimp and prawn polyculture. Eight different diseases and/or symptoms were reported by the surveyed farmers. The white spot disease and the broken antenna and rostrum symptom were the most common in shrimp and prawn species, respectively. In total, 35 chemical and biological products (4 antibiotics, 15 disinfectants, 13 pesticides, 2 feed additives and probiotics) were used to treat and/or prevent diseases in the all farm categories. The major constraints for disease management were limited access to disease diagnostic service, inadequate product application information and lack of knowledge on better management practices. Handling chemicals and preparation of medicated feed with bare hands was identified as a potential occupational health hazard. This study suggests improvements in farmers' knowledge and skill in disease diagnostics and health management practices, and appropriate handling of potentially hazardous chemicals.

Drug resistance, AmpC-β-lactamase and extended-spectrum β-lactamase-producing Enterobacteriaceae isolated from fish and shrimp

The present study aims to detect the production of extended-spectrum beta-lactamases (ESBL) by enterobacteria isolated from samples of fresh shrimp and fish obtained from the retail trade of the city of Sobral, Ceará State, Brazil. All bacterial isolates were submitted to identification and antimicrobial susceptibility testing using aminopenicillin, beta-lactamase inhibitors, carbapenem, 1st, 2nd, 3rd and 4th generation cephalosporins, and monobactam. Three types of beta-lactamases - ESBL, AmpC and KPC - were investigated. 103 strains were identified, and the most frequent species in shrimp and fish samples was Enterobacter cloacae (n = 54). All the strains were resistant to penicillin and more than 50% of the isolates were resistant to ampicillin and cephalothin. Resistance to three 3rd generation cephalosporins (cefotaxime, ceftriaxone and ceftazidime) and one fourth generation cephalosporin (cefepime) was detected in two isolates of E. cloacae from shrimp samples. Phenotypic detection of AmpC was confirmed in seven strains. The ESBL was detected in two strains of E. cloacae from shrimp samples. No strain showed KPC production. These data can be considered alarming, since food (shrimp and fish) may be carriers of enterobacteria resistant to drugs of clinical interest.

Antimicrobial Usage and Antimicrobial Resistance in Animal Production in Southeast Asia: A Review

Southeast Asia is an area of great economic dynamism. In recent years, it has experienced a rapid rise in the levels of animal product production and consumption. The region is considered to be a hotspot for infectious diseases and antimicrobial resistance (AMR). We reviewed English-language peer-reviewed publications related to antimicrobial usage (AMU) and AMR in animal production, as well as antimicrobial residues in meat and fish from 2000 to 2016, in the region. There is a paucity of data from most countries and for most bacterial pathogens. Most of the published work relates to non-typhoidal Salmonella (NTS), Escherichia coli (E. coli), and Campylobacter spp. (mainly from Vietnam and Thailand), Enterococcus spp. (Malaysia), and methicillin-resistant Staphylococcus aureus (MRSA) (Thailand). However, most studies used the disk diffusion method for antimicrobial susceptibility testing; breakpoints were interpreted using Clinical Standard Laboratory Institute (CSLI) guidelines. Statistical models integrating data from publications on AMR in NTS and E. coli studies show a higher overall prevalence of AMR in pig isolates, and an increase in levels of AMR over the years. AMU studies (mostly from Vietnam) indicate very high usage levels of most types of antimicrobials, including beta-lactams, aminoglycosides, macrolides, and quinolones. This review summarizes information about genetic determinants of resistance, most of which are transferrable (mostly plasmids and integrons). The data in this review provide a benchmark to help focus research and policies on AMU and AMR in the region.