Balu P. Kapadnis

Antifungal lactic acid bacteria with potential to prolong shelf‐life of fresh vegetables

Aim:  The aim of this study was to isolate and identify antifungal lactic acid bacteria from fresh vegetables, and evaluate their potential in preventing fungal spoilage of vegetables.

Isolation and characterization of a Lysinibacillus strain B1-CDA showing potential for bioremediation of arsenics from contaminated water

The main objective of this study was to identify and isolate arsenic resistant bacteria that can be used for removing arsenic from the contaminated environment. Here we report a soil borne bacterium, B1-CDA that can serve this purpose. B1-CDA was isolated from the soil of a cultivated land in Chuadanga district located in the southwest region of Bangladesh. The morphological, biochemical and 16S rRNA analysis suggested that the isolate belongs to Lysinibacillus sphaericus. The minimum inhibitory concentration (MIC) value of the isolate is 500 mM (As) as arsenate. TOF-SIMS and ICP-MS analysis confirmed intracellular accumulation and removal of arsenics. Arsenic accumulation in cells amounted to 5.0 mg g−1 of the cells dry biomass and thus reduced the arsenic concentration in the contaminated liquid medium by as much as 50%. These results indicate that B1-CDA has the potential for remediation of arsenic from the contaminated water. We believe the benefits of implementing this bacterium to efficiently reduce arsenic exposure will not only help to remove one aspect of human arsenic poisoning but will also benefit livestock and native animal species. Therefore, the outcome of this research will be highly significant for people in the affected area and also for human populations in other countries that have credible health concerns as a consequence of arsenic-contaminated water.

Antifungal-activity-producing lactic acid bacteria as biocontrol agents in plants

ABSTRACT Fungal infection represents a severe problem that decreases the yield and market value of fruit crops. The use of fungicides is a conventional method to control infections but it is associated with disadvantages, such as hazardous impact on public health, environmental contamination, resistance development among pathogens and high cost of agrochemicals. Biological control is an alternative approach for the treatment of fungal infections. The species of Bacillus, Pseudomonas, Enterobacter, Pantoea, Burkholderia, Lysobacter and Serratia have been successfully used in the control of fungal infections. The mechanisms involved in biocontrol are hyperparasitism or predation, production of antibiotics, lytic enzymes and induction of host resistance. Lactic acid bacteria have been used as biopreservative organisms in food and feed systems. They are a cluster of Gram-positive bacteria and include species of the genera Enterococcus, Lactobacillus, Leuconostoc, Lactococcus and Pediococcus. The ability to produce several antibacterial and antifungal substances confers biopreservation potential to lactic acid bacteria. Many have ‘generally regarded as safe’ status and are considered as safe from both human and environmental points of view. Their isolation is reported from vegetables, aerial plant surfaces, pickled cabbage, grass silage, malted cereals and also from soil. They produce antifungal substances, such as cyclic dipeptides, proteinaceous compounds, organic acids, fatty acids and reuterin. The biocontrol potential of lactic acid bacteria is demonstrated in the prevention of fungal infections of fruits, such as apples and grapes. Thus, living cells or product formulations of antifungal lactic acid bacteria may be prepared and used as an alternative biocontrol technology.

Nonspecific PCR Amplification of the 16S rRNA Gene Segment in Different Bacteria by Use of Primers Specific for Campylobacter, Arcobacter, and Helicobacter spp.

Stephen Marshall and coworkers ([1][1]) reported a simple PCR-restriction fragment length polymorphism (RFLP)-based method for the identification and differentiation of Campylobacter , Arcobacter , and Helicobacter spp. by use of crude lysates of cells or purified DNA from these bacteria. The method

Isolation and characterization of a rare waterborne lytic phage of Salmonella enterica serovar Paratyphi B

A lytic phage of Salmonella serovar Paratyphi B, named φSPB, was isolated from surface waters of the Pavana River in India. Phage φSPB is a member of the Podoviridae family and is morphologically similar to the 7-11 phages of the C3 morphotype of tailed phages, characterized by a very long, cigar-shaped head. The head measured approximately 153 × 57 nm, and the tail size was 12 × 7 nm. The phage was stable over a wide range of pH (4-9) and temperature (4-40 °C). The adsorption rate constant was 4.7 × 10(-10). Latent and eclipse periods were 10 and 15 min, respectively, and the burst size was 100 plaque-forming units/infected cell after 25 min at 37 °C. The phage DNA was 59 kb in size. Ten major proteins were observed on SDS-PAGE, although some of these proteins could be bacterial contaminants. This is the first report of Salmonella enterica subsp. enterica serovar Paratyphi B phage of C3 morphotype from India that has many unique features, such as high replication potential, short replication time, and stability over a wide range of pH and temperature, making it a promising biocontrol agent against the drug-resistant strains of Salmonella Paratyphi B.

Prevalence and antibiotic susceptibility of thermophilic Campylobacters from sources implicated in horizontal transmission of flock colonisation.

Thermophilic Campylobacter are commonly associated with poultry as commensals of the avian gut and are the causative agent responsible for human Campylobacteriosis. This study aimed to establish the prevalence of Campylobacter spp. from environmental sources that have previously been implicated as sources of horizontal transmission. The highest prevalence of thermophilic Campylobacter was found in water samples (87.5%) and lowest from flies (7.2%). Only C. jejuni was isolated from all sources. A secondary aim was to provide a baseline of resistance profiles of Campylobacter spp. isolates obtained. Alarmingly all the C. jejuni isolates from environmental sources as well as humans were multi-drug resistant.

A new bacterial blight of pomegranate caused by Pseudomonas sp. in Maharashtra, India

In the past few decades, pomegranate production in India has greatly suffered from a highly catastrophic bacterial blight disease caused by Xanthomonas axonopodis pv. punicae. Various management strategies have failed to control the disease. During surveys carried out in Maharashtra, India in 2010–2015, an unusual yellow pigmented bacterium was consistently associated with pomegranate showing blight symptoms. Based on morphological, biochemical, 16S rRNA and gyrase B gene sequencing, the bacterium was identified as Pseudomonas sp. Pathogenicity was assessed both by a detached leaf assay method (in vitro) and in pomegranate plantlets (in vivo). To the best of our knowledge, we report Pseudomonas sp. as a cause of new bacterial blight disease of pomegranate in Maharashtra, India in addition to Xanthomonas axonopodis pv. punicae.

Drop collapse assay on lotus leaf (Nelumbo nucifera): a simple and cost effective method for rapid detection of biosurfactants

An alternative technique to perform drop collapse assay for rapid detection of surface active agents produced by microorganisms is described. The method is rapid, simple, economical and sensitive as it can detect the biosurfactant even in low concentrations. The limit of detection for Triton-X 100:0.01 mM (6.25 μg mL -1 ), CTAB: 0.1 mM (36.44 μg mL -1 ) and SDS: 0.001 mM (0.288 μg mL -1 ) using lotus leaf assay. This method uses Lotus (Nelumbo nucifera) leaf as the surface for performing drop collapse studies and can be useful as an initial step for screening microorganisms for biosurfactant production and for detection of surfactant activity. The underline principle was that the leaves of lotus are super hydrophobic, i.e. drops of water roll off free of residue. The lotus leaf has surface roughness and posses water-repellent wax crystals which attribute towards super hydrophobic properties. Hence, if surface active agent capable of reducing surface and interfacial tension acting as wetting agent is produced by the Microbispora sp. V2 even in low concentrations, the drop collapse will occur on lotus leaf and wetting of leaf can occur. Lotus leaf can be a better alternative to microtitre plates as due to its rapidity, sensitivity, simplicity, ease, cost effectiveness and reproducibility. The simplicity of this technique makes it suitable in rapid screening of large number of surfactant producing microbes without the need of expensive high throughput systems. Meghmala S Waghmode 1 , Neha N Patil 1,* , Pallavi S Gaikwad 1 , Aparna B Gunjal 2 , Neelu N Nawani 3