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Glycosylated bacteriocins, known as glycocins, were first discovered in 2011. These bioactive peptides are produced by bacteria to gain survival advantages. They exhibit diverse types of glycans and demonstrate varied antimicrobial activity. Currently, there are 13 experimentally known glycocins, with over 250 identified in silico across different bacterial phyla. Notably, glycocins are recognized for their glycan-mediated antimicrobial activity, proving effective against drug-resistant and foodborne pathogens. Many glycocins contain rare S-linked glycans. Glycosyltransferases (GTs), responsible for transferring sugar to glycocins and involved in glycocin biosynthesis, often cluster together in the producer's genome. This clustering makes them valuable for custom glycoengineering with diverse substrate specificities. Heterologous expression of glycocins has paved the way for the establishment of microbial factories for glycopeptide and glycoconjugate production across various industries. In this review, we emphasize the primary roles of fully and partially characterized glycocins and their glycosylating enzymes. Additionally, we explore how specific glycan structures facilitate these functions in antibacterial activities. Furthermore, we discuss newer approaches and increasing efforts aimed at exploiting bacterial glycobiology for the development of food preservatives and as replacements or complements to traditional antibiotics, particularly in the face of antibiotic-resistant pathogenic bacteria., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2024. Published by Elsevier Inc.)

Global warming exhibits profound effects on plant fitness and productivity. To withstand stress, plants sacrifice their growth and activate protective stress responses for ensuring survival. However, the switch between growth and stress is largely elusive. In the past decade, the role of the target of rapamycin (TOR) linking energy and stress signalling is emerging. Here, we have identified an important role of Glucose (Glc)-TOR signalling in plant adaptation to heat stress (HS). Glc via TOR governs the transcriptome reprogramming of a large number of genes involved in heat stress protection. Downstream to Glc-TOR, the E2Fa signalling module regulates the transcription of heat shock factors through direct recruitment of E2Fa onto their promoter regions. Also, Glc epigenetically regulates the transcription of core HS signalling genes in a TOR-dependent manner. TOR acts in concert with p300/CREB HISTONE ACETYLTRANSFERASE1 (HAC1) and dictates the epigenetic landscape of HS loci to regulate thermotolerance. Arabidopsis plants defective in TOR and HAC1 exhibited reduced thermotolerance with a decrease in the expression of core HS signalling genes. Together, our findings reveal a mechanistic framework in which Glc-TOR signalling through different modules integrates stress and energy signalling to regulate thermotolerance., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Sharma, K, Shukla, Sharma, Awasthi, Mahtha, Yadav and Laxmi.)

Glycosylation affects clinical efficacy and safety; therefore, is a critical quality attribute of therapeutic monoclonal antibodies. Glycans are often labile and complex in patterns, giving rise to macro- and micro-heterogeneity. Recombinant production, diverse geographical locations, associated transportation and storage conditions further compound the problem. Two-way studies comparing glycoprofile of the originator and its given biosimilar are aplenty. However, the extent of analytical variation and similarity in glycoprofile across all approved versions of a drug is hardly explored. Using UHPLC and mass spectrometry, we compared the glycoprofiles of eight rituximab drug samples licensed for sale in India. While the types of glycans were found identical, the abundance of some glycans varied significantly within the tested population. The quality range of glycosylation parameters of the tested sample population differed significantly from the previously established values for US/EU licensed rituximab. As the mean abundance of the 90% of identified glycans falls within ±3SD, the extent of mutual variations amongst tested lots is less significant compared to the extreme deviation from previously established QR limits. Thus, we propose this approach as an orthogonal method to capture glycan variations in licensed versions of mAbs for quality surveillance and in cases where originator samples' are limiting. SIGNIFICANCE: As fluctuation in glycosylation may be of clinical significance, we identify that a one-to-one comparison with originator alone is insufficient in sensing the extent of variations in glycosylation parameters in licensed biosimilars of a given therapeutic mAb. Here we propose that future biosimilarity analysis may include an orthogonal approach of generating an additional combined QR range representing variations across the originator and its biosimilars. The glycosylation profiles of eight rituximab drug samples of different make obtained from the point of sale in India were found identical amongst the tested rituximab versions. However, the QR limits corresponding to important glycosylation parameters differed significantly across all tested samples from the previously established QR limits of US- and EU-licensed rituximab in statistical terms. Such an approach may be useful in defining the true range of glycan variations in licensed versions of therapeutic mAbs., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Root system architecture (RSA) is an important developmental and agronomic trait that is regulated by various physical factors such as nutrients, water, microbes, gravity, and soil compaction as well as hormone-mediated pathways. Phytohormones act as internal mediators between soil and RSA to influence various events of root development, starting from organogenesis to the formation of higher order lateral roots (LRs) through diverse mechanisms. Apart from interaction with the external cues, root development also relies on the complex web of interaction among phytohormones to exhibit synergistic or antagonistic effects to improve crop performance. However, there are considerable gaps in understanding the interaction of these hormonal networks during various aspects of root development. In this review, we elucidate the role of different hormones to modulate a common phenotypic output, such as RSA in Arabidopsis and crop plants, and discuss future perspectives to channel vast information on root development to modulate RSA components.

Induction of heat shock proteins (HSPs) in response to heat stress (HS) is indispensable for conferring thermotolerance. Glc, a fundamental signaling and metabolic molecule, provides energy to stressed seedlings to combat stress. The recovery of stressed plants from detrimental HS in response to Glc is largely mediated by HSPs, but the mechanistic basis of this thermotolerance is not well defined. In this study, we show that Glc has a prominent role in providing thermotolerance. Glc-mediated thermotolerance involves HSP induction via the TARGET OF RAPAMYCIN (TOR)-E2Fa signaling module. Apart from HSPs, TOR-E2Fa also regulates the Arabidopsis ( Arabidopsis thaliana ) ortholog of human Hikeshi , named HIKESHI - LIKE PROTEIN1 ( HLP1 ). Expression of proHLP1 :: GUS in the shoot apical meristem (SAM) after HS coincides with TOR-E2Fa expression, substantiating a role for TOR-E2Fa-HLP1 in providing thermotolerance. We also demonstrate that Glc along with heat could induce proliferation activity in the SAM after HS recovery, which was arrested by the TOR inhibitor AZD-8055. Molecular and physiological studies suggest that HS-activated heat stress transcription factor A1s also positively regulate HLP1 transcription, suggesting convergence of the Glc and HS signaling pathways. Loss of functional HLP1 causes HS hypersensitivity, whereas HLP1 overexpressors display increased thermotolerance. HLP1 binds to the promoters of Glc-regulated HS-responsive genes and promotes chromatin acetylation. In addition, Glc modifies the chromatin landscape at thermomemory-related loci by promoting H3K4 trimethylation (H3K4me3). Glc-primed accumulation of H3K4me3 at thermomemory-associated loci is mediated through HLP1. These findings reveal the novel function of Glc-regulated HLP1 in mediating thermotolerance/thermomemory response., (© 2019 American Society of Plant Biologists. All Rights Reserved.)

The TARGET OF RAPAMYCIN-SNF1-RELATED PROTEIN KINASE 1 (TOR-SnRK1) arms race is a key regulator of plant growth in response to energy fluctuations and stress. Recently, we have identified that two members of the FCS-LIKE ZINC FINGER (FLZ) protein family, FLZ6 and 10, repress SnRK1 signaling and thereby involved in the activation of the TARGET OF RAPAMYCIN (TOR) signaling. In this study, we demonstrate that FLZ6 and 10 are also involved in the regulation of osmotic stress responses. Downregulation of FLZ6 and 10 results in enhanced expression of stress-responsive genes and better resilience towards osmotic stress at the seedling stage. These results indicate that FLZ6 and 10 are involved in the regulation of stress mitigation in plants through directly affecting SnRK1 signaling.

The SNF1-related protein kinase 1 (SnRK1) is a heterotrimeric eukaryotic kinase that interacts with diverse proteins and regulates their activity in response to starvation and stress signals. Recently, the FCS-like zinc finger (FLZ) proteins were identified as a potential scaffold for SnRK1 in plants. However, the evolutionary and mechanistic aspect of this complex formation is currently unknown. Here, in silico analyses predicted that FLZ proteins possess conserved intrinsically disordered regions (IDRs) with a propensity for protein binding in the N and C termini across the plant lineage. We observed that the Arabidopsis FLZ proteins promiscuously interact with SnRK1 subunits, which formed different isoenzyme complexes. The FLZ domain was essential for mediating the interaction with SnRK1α subunits, whereas the IDRs in the N termini facilitated interactions with the β and βγ subunits of SnRK1. Furthermore, the IDRs in the N termini were important for mediating dimerization of different FLZ proteins. Of note, the interaction of FLZ with SnRK1 was confined to cytoplasmic foci, which colocalized with the endoplasmic reticulum. An evolutionary analysis revealed that in general, the IDR-rich regions are under more relaxed selection than the FLZ domain. In summary, the findings in our study reveal the structural details, origin, and evolution of a land plant-specific scaffold of SnRK1 formed by the coordinated actions of IDRs and structured regions in the FLZ proteins. We propose that the FLZ protein complex might be involved in providing flexibility, thus enhancing the binding repertoire of the SnRK1 hub in land plants., (© 2018 Jamsheer K et al.)

HIV-1 virus entry into target cells requires the envelope glycoprotein (Env) to first bind the primary receptor, CD4 and subsequently the co-receptor. Antibody access to the co-receptor binding site (CoRbs) in the pre-receptor-engaged state, prior to cell attachment, remains poorly understood. Here, we have demonstrated that for tier-1 Envs, the CoRbs is directly accessible to full-length CD4-induced (CD4i) antibodies even before primary receptor engagement, indicating that on these Envs the CoRbs site is either preformed or can conformationally sample post-CD4-bound state. Tier-2 and tier-3 Envs, which are resistant to full-length CD4i antibody, are neutralized by m36.4, a lower molecular mass of CD4i-directed domain antibody. In some tier-2 and tier-3 Envs, CoRbs is accessible to m36.4 even prior to cellular attachment in an Env-specific manner independent of their tier category. These data suggest differential structural arrangements of CoRbs and varied masking of ligand access to the CoRbs in different Env isolates., (Copyright © 2018 Elsevier Inc. All rights reserved.)

SNF1-related protein kinase 1 (SnRK1) is a central regulator of plant growth during energy starvation. The FCS-like zinc finger (FLZ) proteins have recently been identified as adaptor proteins which facilitate the interaction of SnRK1 with other proteins. In this study, we found that two starvation-induced FLZ genes, FLZ6 and FLZ10, work as repressors of SnRK1 signalling. The reduced expression of these genes resulted in an increase in the level of SnRK1α1, which is the major catalytic subunit of SnRK1. This lead to a concomitant increase in phosphorylated protein and SnRK1 activity in the flz6 and flz10 mutants. FLZ6 and FLZ10 specifically interact with SnRK1α subunits in the cytoplasmic foci, which co-localized with the endoplasmic reticulum. In physiological assays, similar to the SnRK1α1 overexpression line, flz mutants showed compromised growth. Further, growth promotion in response to favourable growth conditions was found to be attenuated in the mutants. The enhanced SnRK1 activity in the mutants resulted in a reduction in the level of phosphorylated RIBOSOMAL S6 KINASE and the expression of E2Fa and its targets, indicating that TARGET OF RAPAMYCIN-dependent promotion of protein synthesis and cell cycle progression is impaired. Taken together, this study uncovers a plant-specific modulation of SnRK1 signalling., (© 2018 The Authors The Plant Journal © 2018 John Wiley & Sons Ltd.)

Efficient cleavage of HIV-1 Env gp160 into its constituent subunits correlates with selective binding to neutralizing antibodies and are the closest mimetic of native, functional Envs. This was first demonstrated with the clade B Env, JRFL. The correlation between efficient cleavage and selective binding to neutralizing antibodies is the guiding principle for immunogen design for HIV vaccine. We have recently reported that Envs 4-2.J41 (clade C) and JRCSF (clade B) are also efficiently cleaved and show similar properties. However, an efficiently cleaved, membrane-bound clade A Env suitable for genetic vaccination has not been directly demonstrated. Here we report that BG505 and a new clade A Env, QB726.70M.ENV.C4 (or A5) are efficiently cleaved on cell membrane. A5 shows desirable antigenic properties comparable with BG505 on cell surface. A5SOSIP in supernatant displays majority of bNAb binding epitopes. Thus, both BG505 and A5 Envs can be used in DNA prime-protein boost vaccination studies., (Copyright © 2017 Elsevier Inc. All rights reserved.)

An ideal HIV-1 Env immunogen is expected to mimic the native trimeric conformation for inducing broadly neutralizing antibody responses. The native conformation is dependent on efficient cleavage of HIV-1 Env. The clade B isolate, JRFL Env is efficiently cleaved when expressed on the cell surface. Here, for the first time, we report the identification of a native clade C Env, 4-2.J41 that is naturally and efficiently cleaved on the cell surface as confirmed by its biochemical and antigenic characteristics. In addition to binding to several conformation-dependent neutralizing antibodies, 4-2.J41 Env binds efficiently to the cleavage-dependent antibody PGT151; thus validating its native cleaved conformation. In contrast, 4-2.J41 Env occludes non-neutralizing epitopes. The cytoplasmic-tail of 4-2.J41 Env plays an important role in maintaining its conformation. Furthermore, codon optimization of 4-2.J41 Env sequence significantly increases its expression while retaining its native conformation. Since clade C of HIV-1 is the prevalent subtype, identification and characterization of this efficiently cleaved Env would provide a platform for rational immunogen design.

In the present study by examining pseudoviruses expressing patient chimeric envelopes (Envs) made between an IgG1b12 (b12)-sensitive (2-5.J3) and a b12-resistant (4.J22) HIV-1 clade C envelope, we identified determinants in the V2C2 region that governed susceptibility to b12 monoclonal antibody, but not to other CD4 binding site antibodies. Interestingly, when the V2C2 sequence of the 2-5.J3 Env was transferred to other b12-resistant primary clade C Envs, their susceptibility to b12 varied, indicating that this effect was context dependent. In addition, we identified determinants within the V2 region in the b12-resistant envelope that significantly modulated the neutralization of Env-pseudotyped viruses to PG9/PG16 MAbs. The enhanced neutralization susceptibilities of Envs to b12 and PG9 MAbs were correlated with increased exposure of their corresponding epitopes highlighting vulnerabilities in the V2C2 region that altered Env conformation necessary for the efficient accessibility of b12 and PG9 antibodies., (Copyright © 2014 Elsevier Inc. All rights reserved.)

The Pasteurella multocida subsp. multocida B:2 serotype causes hemorrhagic septicemia in bubalines with high morbidity and mortality in the Indian subcontinent. We report the draft genome sequence of Pasteurella multocida strain VTCCBAA264 isolated from the small-intestine of a buffalo calf that died of high fever., (Copyright © 2014 Vaid et al.)

Buffalopox virus (BPXV), a close variant of vaccinia virus (VACV) has emerged as a zoonotic pathogen. The host tropism of poxviruses is governed by host-range genes. Among the host-range genes: E3L, K3L, and C7L are essential for virus replication by preventing interferon resistance, whereas B5R is essential for spread of the virus and evasion from the host's immune response as in VACV. We report sequence analysis of host-range genes: E3L, K3L, C7L, and membrane protein gene (B5R) of BPXVs from buffalo, cattle, and human from recent outbreaks in India-their phylogenetic relationship with reference strain (BP4) and other Orthopoxviruses. BPXVs revealed a sequence homology with VACVs including zoonotic Brazilian VACV-like viruses. The aa sequences of E3L and K3L genes were 100 % similar in buffalo, cattle, and human isolates. However, four significant point mutations (I11K; N12K and S36F in C7L gene and D249G in B5R gene) were observed specific to buffalo isolate only. This signifies that different strains of BPXV were circulated during the outbreak. The mutations in C7L and B5R could play an important role in adaptation of BPXV in human and cattle which needs further functional studies. The strain of BPXV isolated from buffalo may not be adopted in human and cow. Various point mutations were observed in the host-range genes of reference strain (BPXV-BP4) which may be due to several passages of virus in cell culture. The phylogeny constructed based on concatenated gene sequences revealed that BPXVs are not as closely related to vaccine strain (Lister and Lister-derived strain-LC16m8), as hypothesized earlier, rather they are more closely related to reference strain (BPXV-BP4) and other vaccinia and vaccinia-like viruses such as Passatempo and Aracatuba viruses. The availability of information regarding host tropism determinants would allow us to understand molecular mechanism of species tropism of poxviruses which would be useful in unveiling new strategies to control zoonotic poxviral infections.

Background: The acute infections which are caused by Toxoplasma gondii, Rubella virus, Cytomegalovirus (CMV) and the Herpes Simplex Virus (HSV-2) during pregnancy are often associated with adverse foetal outcomes and reproductive failures. In the Indian context, the exact seroprevalence of these infections is not known due to unavailability of baseline data., Aims: The present study was undertaken to determine the serological evidence of the acute TORCH infections in women who were in the first trimesters of their pregnancies in and around Varanasi, north India., Settings and Design: This study was carried out in the Sir Sunderlal Hospital, Varanasi and in the Department of Microbiology, Institute of Medical Sciences, BHU, Varanasi, UP, India. The study population involved pregnant women with bad obstetric histories, who were in the first trimester of their pregnancy., Methods and Materials: Sera were collected from the women with Bon and they were tested for the presence of specific IgM antibodies against the TORCH infections by ELISA., Statistical Analysis: A 95% confidence interval was calculated for the positive cases in each of the TORCH components., Results: The specific IgM antibodies were found to be positive in 74(19.4%) cases for toxoplasmosis, in 126 (30.4%) cases for the Rubella virus, in 130 (34.7%) cases for CMV and in 151 samples (33.5%) for the HSV-2 infections., Conclusions: The study showed a high prevalence of the infections which were caused by the TORCH complex amongst pregnant women with bad obstetric histories. Therefore, all the antenatal cases should be routinely screened for the TORCH infections, for carrying out early interventions to prevent foetal loss.

A collection of ten strains of Vibrio cholerae O139, comprising six isolates from Eichhornia crassipes, two from water of the River Ganga, and one each from a well and a hand pump, were characterized. All the strains carried the CTX genetic element (ctxA, zot, and ace) except for the st gene and carried structural and regulatory genes for toxin-coregulated pilus (tcpA, tcpI, and toxR), adherence factor (ompU), and accessory colonization factor (acfB); all produced cholera toxin (CT). These strains were resistant to trimethoprim, sulfamethoxazole, streptomycin, and to the vibriostatic agent pteridine. Results obtained by ribotyping and enterobacterial repetitive intergenic consensus sequence-PCR fingerprint analysis indicate that multiple clones of toxigenic-pathogenic V. cholerae O139 were present in the aquatic environment.

A total of 26 strains of Vibrio cholerae, including members of the O1, O139, and non-O1, non-O139 serogroups from both clinical and environmental sources, were examined for the presence of genes encoding cholera toxin (ctxA), zonula occludens toxin (zot), accessory cholera enterotoxin (ace), hemolysin (hlyA), NAG-specific heat-stable toxin (st), toxin-coregulated pilus (tcpA), and outer membrane protein (ompU), for genomic organization, and for the presence of the regulatory protein genes tcpI and toxR in order to determine relationships between epidemic serotypes and sources of isolation. While 22 of the 26 strains were hemolytic on 5% sheep blood nutrient agar, all strains were PCR positive for hlyA, the hemolysin gene. When multiplex PCR was used, all serogroup O1 and O139 strains were positive for tcpA, ompU, and tcpI. All O1 and O139 strains except one O1 strain and one O139 strain were positive for the ctxA, zot, and ace genes. Also, O1 strain VO3 was negative for the zot gene. All of the non-O1, non-O139 strains were negative for the ctxA, zot, ace, tcpA, and tcpI genes, and all of the non-O1, non-O139 strains except strain VO26 were negative for ompU. All of the strains except non-O1, non-O139 strain VO22 were PCR positive for the gene encoding the central regulatory protein, toxR. All V. cholerae strains were negative for the NAG-specific st gene. Of the nine non-ctx-producing strains of V. cholerae, only one, non-O1, non-O139 strain VO24, caused fluid accumulation in the rabbit ileal loop assay. The other eight strains, including an O1 strain, an O139 strain, and six non-O1, non-O139 strains, regardless of the source of isolation, caused fluid accumulation after two to five serial passages through the rabbit gut. Culture filtrates of all non-cholera-toxigenic strains grown in AKI media also caused fluid accumulation, suggesting that a new toxin was produced in AKI medium by these strains. Studies of clonality performed by using enterobacterial repetitive intergenic consensus sequence PCR, Box element PCR, amplified fragment length polymorphism (AFLP), and pulsed-field gel electrophoresis (PFGE) collectively indicated that the V. cholerae O1 and O139 strains had a clonal origin, whereas the non-O1, non-O139 strains belonged to different clones. The clinical isolates closely resembled environmental isolates in their genomic patterns. Overall, there was an excellent correlation among the results of the PCR, AFLP, and PFGE analyses, and individual strains derived from clinical and environmental sources produced similar fingerprint patterns. From the results of this study, we concluded that the non-cholera-toxin-producing strains of V. cholerae, whether of clinical or environmental origin, possess the ability to produce a new secretogenic toxin that is entirely different from the toxin produced by toxigenic V. cholerae O1 and O139 strains. We also concluded that the aquatic environment is a reservoir for V. cholerae O1, O139, non-O1, and non-O139 serogroup strains.

The synthesis of fifteen new 1-aryl-2-amino-3-(4-arylthiazol-2-yl)/(benzothiazol-2-yl)gua nidines is described. They were screened for their antimicrobial susceptibility by the standard disc diffusion method of the World Health Organization (WHO) and the activities compared with that of standard strain of Escherichia coli NCTC 10418. The sensitive aminoguanidines were further subjected to the minimum inhibitory concentration (MIC) test.

In a hospital-based study, stool samples from 2095 patients of all ages were examined for different fungal, protozoal and bacterial enteropathogens over a period of 2 years (July 1994-June 1996). Cryptosporidium was detected in 151 specimens (7.2%) and was the third commonest pathogen found. The highest prevalence of this organism was in the group aged 16-45 years and during the rainy months (July-Oct.). Diarrhoea caused by the protozoon was of mild to moderate severity and features of dysentery were absent. Amongst other enteropathogens, Candida albicans was the most frequently isolated, followed by enteropathogenic and enterotoxigenic Escherichia coli, Salmonella spp., Campylobacter jejuni, Entamoeba histolytica, Giardia duodenalis (lamblia), Shigella spp., Vibrio cholerae and Aeromonas spp.

Of 28 isolates of Vibrio cholerae non-O1 (10 from diarrhoeal patients and 18 from environmental sources) examined for haemolytic activity and its correlation, if any, with enterotoxic activity, 24 showed haemolysis. The four non-haemolytic isolates showed haemolysis after consecutive passages through rabbit ileal loops (RILs). The titres of haemolytic activity were 4-64 HU/ml irrespective of their source. Eight (28.5%) of the non-O1 isolates caused fluid accumulation; six (25%) were haemolytic and two (50%) non-haemolytic. The remaining isolates showed enterotoxic activity after one-to-three consecutive passages through RILs irrespective of their haemolytic character and source. Environmental isolates caused significantly more fluid accumulation than the diarrhoeal isolates. All these isolates reverted to their original non-toxigenic character on repeated subculture or on storage in the laboratory, but continued to show haemolytic activity. The results of the present study indicate that V. cholerae non-O1 strains are potentially enterotoxigenic independent of their haemolytic character and source, and enterotoxin, not haemolysin, is the factor most likely to be responsible for their enterotoxic activity.

An improved synthetic medium (M4) comprising syncase medium supplemented with sodium chloride (1%) and sucrose (0.5%) pH adjusted to 7.4 was developed for a better production of the new cholera toxin (NCT). The culture filtrates prepared in the M4 medium caused significantly (P > 0.05) more fluid accumulation than that in syncase medium. Crude toxin, prepared in the M4 medium with V. cholerae O1 strains (X-392 and 2740-80) caused a reaction similar to that of the same amount of NCT (32 micrograms) prepared in the syncase medium. The neutralization of the optimal loop reacting dose of the NCT prepared in the M4 medium by anti-NCT raised against syncase prepared toxin indicates the release of the same kind of toxin in both media. These observations indicate that the modified M4 medium may be used for NCT preparation and further characterization. All the strains of Vibro cholerae O139 used in this study produced a toxin antigenically similar to NCT.

One hundred and eight strains of Aeromonas from clinical and environmental samples were speciated. Seven species were identified, the most prevalent of which was A. hydrophila. Experimental studies in an animal model with 36 representative strains of different species revealed that all strains could cause significant fluid accumulation in rabbit ileal loops. Of 107 strains showing single or multiple antimicrobial resistance, the highest incidence of resistance was shown for beta-lactam antibiotics other than cefotaxime. Transferable resistance plasmids, encoding resistance to ampicillin, cephalexin, cefoxitin, erythromycin and furazolidone, either alone or in combination, were detected in 35 strains. A further proportion of strains could be cured of one or more resistance markers, including resistance to nalidixic acid, and this was accompanied by the loss of plasmid DNA. The plasmids ranged in size between 85.6 and > 1 50 kb.

Non-cultivable, pathogenic O1 and non-O1 Vibrio cholerae and Aeromonas spp. were resuscitated from aquatic arthropods and plant homogenate respectively, by rabbit ileal loop (RIL) assay. These organisms adhered to the aquatic arthropod Gerris spinolae and various species of phytoplankton in the River Ganga, but failed to grow after direct inoculation on artificial media except for only 10 homogenates of the arthropod. The number of non-O1 V. cholerae and Aeromonas recovered on direct inoculation of G. spinolae homogenates were in the order of 10(5)-10(6) whereas those of the Ganga water were 10(2)-10(3) ml-1. A total of 119 strains of O1 and non-O1 V. cholerae and Aeromonas spp. (69 isolates from G. spinolae and 50 from aquatic plants) were recovered from the loop contents. The results indicate that production of the enzyme chitinase by O1 and non-O1 V. cholerae and Aeromonas spp. might facilitate their adsorption and multiplication on different species of zoo- and phyto-plankton. Most of the isolates were enterotoxic, haemolytic and resistant to different antibiotics. This study suggests that species of zoo- and phyto-planktons, until now not reported to be associated with O1 and non-O1 V. cholerae, may act as reservoirs of these organisms as well as different species of Aeromonas in a fresh-water riverine ecosystem.