Comparative molecular studies of halophilic bacteria from saline water and soil in the Saudi environment / Estudos moleculares comparativos de bactérias halofílicas de água salina e solo no meio ambiente saudita

Halophilic bacteria are microorganisms that grow optimally in the presence of the very high concentration of sodium chloride. Halophiles are vital sources of various enzymes including hydrolases, which are very stable and catalytically highly efficient at high salt concentration and other extreme conditions such as high temperature, pH and presence of organic solvents. Several hydrolases such as amylases, proteases, and lipases have been obtained from halophilic bacteria and are commonly used for various industrial applications. We initiated a screening to isolate and characterize the halophilic bacteria from the Red Sea, which is one of the saltiest bodies of water in the world. Water and soil samples, collected from the Red Sea coast, Jeddah, Saudi Arabia, were screened for isolation of halophilic bacteria. Ten bacterial isolates were obtained, which were characterized by biochemical tests and 16S rRNA gene sequencing. Hydrolase producing bacteria among the isolates were screened by plate assay on starch and gelatin agar plates for amylase and protease, respectively. Two bacterial isolates i.e. Bacillus glycinifermentans S3 and Enterobacter cloacae W1were found to possess significant amylase and protease activity.

Bactérias halofílicas são microrganismos que crescem de maneira ideal na presença de uma concentração muito alta de cloreto de sódio. Halófilos são fontes vitais de várias enzimas, incluindo hidrolases, que são muito estáveis e cataliticamente altamente eficientes em alta concentração de sal e outras condições extremas, como alta temperatura, pH e presença de solventes orgânicos. Várias hidrolases como amilases, proteases e lipases foram obtidas a partir de bactérias halofílicas e são comumente usadas para várias aplicações industriais. Iniciamos uma triagem para isolar e caracterizar as bactérias halofílicas do Mar Vermelho, que é um dos corpos de água mais salgados do mundo. Amostras de água e solo, coletadas na costa do Mar Vermelho, Jeddah, na Arábia Saudita, foram examinadas quanto ao isolamento de bactérias halofílicas. Foram obtidos dez isolados bacterianos, caracterizados por testes bioquímicos e seqüenciamento do gene 16S rRNA. As bactérias produtoras de hidrolase entre os isolados foram triadas por ensaio em placa em placas de amido e ágar de gelatina para amilase e protease, respectivamente. Verificou-se que dois isolados bacterianos, isto é, Bacillus glycinifermentans S3 e Enterobacter cloacae W1, possuíam significativa atividade de amilase e protease.

Antibiotic resistance profiling of marine halophilic bacteria and haloarchaea.

Drug resistance in microorganisms is an emerging phenomenon that poses challenges to public health and treatment. The reservoir of drug resistance genes found in the resistome of environmental isolates in aquatic saline systems has been augmenting continuously. The spread of drug resistance is attributed to the dissemination of drug resistant pathogens occurring in sewage and wastewater released in the marine environments like seas. Halophiles are salt loving organisms that are found naturally in these marine environments, sea water, salterns and lakes. The present study aimed at investigation of the antibiotic resistance profile of halophiles isolated from marine ecosystems of the coastal Maharashtra, India using disk diffusion method. The plausible mechanism of drug resistance in the marine halophiles was investigated by detecting plasmids and antibiotic efflux pumps using EtBr-Cart wheel assay. The haloarchaea, Haloarcula sp. RR14 and Halovivax sp. RT5 showed multidrug resistance and presence of efflux pumps (MICEtBr= 0.5 µg/ml). The resistance of gram positive halophiles was in following order: Salimicrobium salexigens RR5 > Salimicrobium flavidum RR2 > Alkalibacillus almallahensis RR3. Amongst gram negative halophiles, their resistance was in following order: Halomonas smyrnensis RR7 > Halomonas koreensis RR1 > Marinobacter oulmenensis RR6. Plasmids were detected in Haloarcula sp., Halomonassp. and Marinobacter sp. The present study related to antibiotic resistance of halophiles from marine environment is significant as some of the marine halophilic isolates like Halomonas sp. have been reported as potential pathogens in recent times.

Structure and Functional Relationship of Halotolerant Proteins- A Review.

With increasing need for various industries for stable enzymes which can outperform under harsh conditions of pH, temperature and saline environments evoke the need for extensive research on extremophilic microorganisms which found to be a suitable source for enzymes with novel properties. Especially, enzymes capable of functioning over a wide range of salt concentrations are in great demand for industries which mainly include proteases, xylanases, mannases, lipases, amylases and cellulases. In case of halophilic, extremely halophilic or halotolerant organisms it has been scientifically proven that there is a correlation between the salt requirement and bacterial growth and its enzymatic activities. When compared to halophilic organism, halotolerant bacteria can survive from low to moderate level of salinity, which gives them unique property over halophilic organisms. The halotolerant organisms synthesize enzymes with greater conformational stability and they can be potentially employed in many industrial processes even under harsher conditions over a range of salinity conditions where enzymes from non-halophilic and halophilic organisms found to be unfit. Less research has been carried out on halotolerant organisms when compared to thermophilic, alkaliphilic and halophilic organisms and so yet to explore the biotechnological applications of these halotolerant enzymes to use them in industrial applications.

Screening and isolation of halophilic bacteria producing industrially important enzymes

Halophiles are excellent sources of enzymes that are not only salt stable but also can withstand and carry out reactions efficiently under extreme conditions. The aim of the study was to isolate and study the diversity among halophilic bacteria producing enzymes of industrial value. Screening of halophiles from various saline habitats of India led to isolation of 108 halophilic bacteria producing industrially important hydrolases (amylases, lipases and proteases). Characterization of 21 potential isolates by morphological, biochemical and 16S rRNA gene analysis found them related to Marinobacter, Virgibacillus, Halobacillus, Geomicrobium, Chromohalobacter, Oceanobacillus, Bacillus, Halomonas and Staphylococcus genera. They belonged to moderately halophilic group of bacteria exhibiting salt requirement in the range of 3-20%. There is significant diversity among halophiles from saline habitats of India. Preliminary characterization of crude hydrolases established them to be active and stable under more than one extreme condition of high salt, pH, temperature and presence of organic solvents. It is concluded that these halophilic isolates are not only diverse in phylogeny but also in their enzyme characteristics. Their enzymes may be potentially useful for catalysis under harsh operational conditions encountered in industrial processes. The solvent stability among halophilic enzymes seems a generic novel feature making them potentially useful in non-aqueous enzymology.

Chemotactic responses to gas oil of Halomonas spp. strains isolated from saline environments in Argentina / Respuesta quimiotáctica hacia gas oil de cepas de Halomonas spp. aisladas de ambientes salinos de Argentina

In this study, two halophilic bacterial strains isolated from saline habitats in Argentina grew in the presence of gas oil. They were identified as Halomonas spp. and Nesterenkonia sp. by 16S ribosomal RNA sequencing. Chemotaxis towards gas oil was observed in Halomonas spp. by using swimming assays.

En el presente trabajo se aislaron dos cepas bacterianas halofílicas a partir de muestras obtenidas en ambientes salinos de Argentina, que crecieron en presencia de gasoil como única fuente de carbono. Las cepas aisladas se identificaron como Halomonas spp. y Nesterenkonia sp. mediante secuenciación del gen del ARN ribosomal 16S. En ensayos de swimming, las cepas del genero Halomonas spp. mostraron una respuesta quimiotáctica hacia el gas oil.

Isolation and phylogenetic characterization of extremophiles from marakanam salterns.

Salterns are highly saline environments, where salt concentrations inhibit growth of most of the organisms. Recent studies have revealed that these environments are loaded with a variety of microbial life. In the present study, sediment samples were collected from Salterns of Marakanam, Tamil Nadu and were analyzed for presence of any halotolerant bacteria in them. Twelve isolates were obtained after processing the samples and were characterized. Two isolates among the total were selected based on unique biochemical characteristics and were further studied. The 16S rRNA gene sequencing revealed that these isolates are Pontibacillus chungwensis (P1) and Bacillus barbaricus (P2). The isolate P2 has not yet been reported to be isolated from such an environment and no reports of salt tolerance characteristics. In addition to that the 16S rRNA gene analysis results showed the sequence of strain to be located in a different domain well away from Bacillus barbaricus type strain. Further work on the bacterium might result in the strain P2 being claimed as novel. Any study on the microbial life of these salterns is helpful in extending our knowledge on the microorganisms present in such environments and their physiology which might be useful in agriculture, industry and Costal areas.

Halophilic (aerobic) bacterial growth rate of mangrove ecosystem.

Mangroves are woody specialized trees of tropics and are valuable flora contributing to economical, ecological, scientific and cultural resources. They thrive in salty environments like coastal regions and are aid towards disaster management facing the onslaught of giant waves such as Tsunami. Analysis of mangrove soil on the banks of the Adyar river, behind the Theosophical society campus, Adyar, Chennai, India, gave a startling revelation of microorganisms that can tolerate different salinity ranges. Previous studies in Pichavaram delta, have reported bacterial isolates such as nitrogen fixing bacteria, halophiles and several others. However their efficiency in the growth of mangrove forest has been studied to a lesser extent. The present study has been designed and formulated to estimate halophilic(aerobic) bacterial load from mangroves soil sample based on depth and salinity of the soil and further the efficiency if any of these isolates in the growth of mangroves. Results have been correlated and a cohesive conclusion reached for further intensive research. This study throws light on the ecology of the bacterial population in the coastal marine environment inhabited by mangroves and its possible role in disaster mitigation.