Diversity of moderately halophilic bacteria producing extracellular hydrolytic enzymes

AIMS: The aim of this study was to determine the diversity of moderately halophilic bacteria with hydrolase activities. METHODS AND RESULTS: Screening bacteria from different hypersaline environments in South Spain led to the isolation of a total of 122 moderately halophilic bacteria able to produce different hydrolases (amylases, DNases, lipases, proteases and pullulanases). These bacteria are able to grow optimally in media with 5-15% salts and in most cases up to 20-25% salts. In contrast to strains belonging to previously described species, that showed very little hydrolase activities, environmental isolates produced a great variety of hydrolases. These strains were identified as members of the genera: Salinivibrio (55 strains), Halomonas (25 strains), Chromohalobacter (two strains), Bacillus-Salibacillus (29 strains), Salinicoccus (two strains) and Marinococcus (one strain), as well as eight non-identified isolates. CONCLUSIONS: Moderately halophilic bacteria are a source of hydrolytic enzymes such as amylases, DNases, lipases, proteases and pullulanases. SIGNIFICANCE AND IMPACT OF THE STUDY: Although most culture collection strains are not able to produce hydrolases, it has been shown that environmental isolates can produce these potentially biotechnological important enzymes.     

Hydrolytic Enzymes Producing Bacterial Endophytes of Some Poaceae Plants

Endophytic bacteria represent microorganisms that live during the whole life cycle within the tissues of healthy plants without causing any obvious signs of disease. In this study, the ability of 128 endophyte bacterial isolates from some cultivated and wild grain plants (Poaceae family) in Van, Turkey, were investigated in terms of producing several extracellular hydrolytic enzymes. It was demonstrated that lipases, proteases, amylases, cellulases, pectinases, and xylanases were produced by the bacteria with relative frequencies of 74.2%, 65.6%, 55.4%, 32%, 21.8%, and 7.8%, respectively. In addition, molecular identification of a certain number of isolates selected according to their enzyme-producing capabilities was performed by 16S rRNA gene sequencing using a next-generation sequencing platform. As a result of the analysis, the isolates yielded certain strains belonging to Pseudomonas, Micrococcus, Paenibacillus, Streptococcus, Curtobacterium, Chryseobacterium, and Bacillus genera. Also, the strain G117Y1T was evaluated as a member of potential novel species based on 16S rRNA sequencing results.     

16S rRNA-based bacterial diversity in the organic-rich sediments underlying oxygen-deficient waters of the eastern Arabian Sea

The eastern Arabian Sea has a unique and permanent oxygen minimum zone (OMZ) that extends along the western continental margin of India. The sediment below this region is rich in organic matter. This study describes the bacterial community structure and diversity in OMZ sediments of the eastern Arabian Sea (AS) through 16S rRNA clone library analysis. Phylogenetic analysis of the sequences demonstrated that phylum Proteobacteria (52%), followed by Planctomycetes (12.7%), Chloroflexi and an unidentified bacterial group (8.8% each) were represented in the library. Deltaproteobacteria was the dominant class (62.5%) in phylum Proteobacteria with clones falling in orders Syntrophobacterales and Desulfovibrionales. Few minor phylogenetic groups, corresponding to Spirochetes, Firmicutes, Acidobacteria and Verrucomicrobia were found. Unidentified candidate groups falling in OP11, OP8 and OP3 were represented by 0.9, 2.9 and 3.9%, respectively and two clusters of the cloned sequences in this study showed very low identity to known sequences. This is the first report that discusses the phylogenetic groups in the OMZ sediments of eastern Arabian Sea individually and compares it with available data from marine hypoxic locales and water mass. LIBSHUFF statistics revealed high richness of the bacterial community of the Arabian Sea OMZ (AS-OMZ) compared to the other regions.     

Isolation of Moderately Halophilic <Emphasis Type="Italic">Pseudoalteromonas</Emphasis> Producing Extracellular Hydrolytic Enzymes from Persian Gulf

Extracellular hydrolytic enzymes such as amylases, proteases, lipases and DNases have quite diverse potential usages in different areas such as food industry, biomedical sciences and chemical industries, also it would be of great importance to have available enzymes showing optimal activities at different values of salt concentrations and temperature. Halophiles are the most likely source of such enzymes, because not only their enzymes are salt-tolerant, but many are also thermotolerant. The purpose of this study was isolation of hydrolytic extracellular enzyme producing halophilic bacteria from water and sediment of the Persian Gulf. Isolated bacteria from water and sediment were inoculated in media with concentration of 0–20% NaCl to determine the optimum salt concentration for growth, isolates were also inoculated in 4 types of solid medium containing substrates of 3 extracellular hydrolytic enzymes including amylase, Protease and Lipase, to determine the quantitative detection of enzyme production, selected strains after more accurate physiological and biochemical studies were identified regarding phylogeny and molecular characteristics using 16S rRNA technique. Isolated enzyme producing bacteria belong to Pseudoalteromonas genera.     

黄海海域海洋沉积物细菌多样性分析

【背景】海洋独特的环境造就了海洋生物的多样性,海洋沉积物中细菌对海洋环境具有至关重要的作用。【目的】研究陆地土壤和海洋沉积物间细菌群落相似性和差异性,以便更好地认识海洋细菌多样性,深入了解沉积物细菌在海洋环境中的潜在作用。【方法】从中国黄海海域及大连市大黑山脚下分别采集样品,以陆地土壤为对照,采用16SrRNA基因高通量测序技术分析海洋沉积物的细菌群落结构。【结果】海洋沉积物样品中芽孢杆菌纲(Bacilli)、鞘氨醇单胞菌属(Sphingomonas)和芽孢杆菌属(Bacillus)丰度高于陆地土壤样品;海洋沉积物中亚硝化单胞菌(unculturedbacterium f. Nitrosomonadaceae)和厌氧绳菌(uncultured bacterium f. Anaerolineaceae)丰度虽低于陆地土壤,但丰度值也均高于1%;样品分类学统计显示酸杆菌门(Acidobacteria)在海洋沉积物和陆地土壤样品中的序列丰度比例都较大,鞘氨醇单胞菌属(Sphingomonas)在海洋沉积物样品中的序列丰度大于陆地土壤样品。【结论】海洋沉积物细菌多样性可作为海洋环境恢复情况的重...     

Surface Display of Bacterial Laccase CotA on <Emphasis Type="Italic">Escherichia coli</Emphasis> Cells and its Application in Industrial Dye Decolorization

Laccase CotA from Bacillus subtilis 168 was successfully displayed on the membrane of Escherichia coli cells using poly-γ-glutamate synthetase A protein (PgsA) from B. subtilis as an anchoring matrix. Further analyses demonstrated that the fusion protein PgsA/CotA efficiently translocates to the cell surface of E. coli with an enzymatic activity of 65 U/10⁸ cells. Surface-displayed CotA was shown to possess improved enzymatic properties compared with those of the wild-type CotA, including higher thermal stability (above 90% activity at 70 °C and nearly 40% activity at 90 °C after 5-h incubation) and stronger inhibitor tolerance (approximately 80 and 65% activity when incubated with 200 and 400 mM NaCl, respectively). Furthermore, the whole-cell system was demonstrated to have high enzymatic activity against anthraquinone dye, Acid Blue 62, triphenylmethane dye, Malachite Green, and azo dye, Methyl Orange with the decolorization percentages of 91, 45, and 75%, after 5-h incubation, respectively.     

Occurrence and diversity of mesophilic Shewanella strains isolated from the North-West Pacific Ocean

Although bacteria of the genus Shewanella belong to one of the readily cultivable groups of "Gammaproteobacteria", little is known about the occurrence and abundance of these microorganisms in the marine ecosystem. Studies revealed that of 654 isolates obtained from marine invertebrates (ophiuroid Amphiopholis kochii, sipuncula Phascolosoma japonicum, and holothurian Apostichopus japonicus, Cucumaria japonica), seawater and sediments of the North-West Pacific Ocean (i.e. the Sea of Japan and Iturup Is, Kurile Islands), 10.7% belonged to the genus Shewanella. The proportion of viable Shewanella species varied from 4% to 20% depending on the source of isolation. From the isolation study, representative strains of different phenotypes (from seventy presumptive Shewanella strains) were selected for detailed characterization using phenotypic, chemotaxonomic, and phylogenetic testing. 16S rDNA sequence-based phylogenetic analysis confirmed the results of tentative identification and placed the majority of these strains within only a few species of the genus Shewanella with 98-99% of 16S rDNA sequences identity mainly with S. japonica and S. colwelliana, suggesting that the strains studied might belong to these species. Numerically dominant strains of S. japonica were metabolically active and produced proteinases (gelatinases, caseinases), lipases, amylases, agarases, and alginases. Shewanella strains studied demonstrated weak antimicrobial and antifungal activities that might be an indication of their passive role in the colonization on living and non-living surfaces.     

16S rDNA sequence analysis of culturable marine biofilm forming bacteria from a ship's hull

Marine bacteria from the hull of a ship in the form of biofilms or microfouling were isolated, cultured, and identified by phylogenetic analysis using 16S rDNA sequences. With an average length of 946 bp, all the 16 sequences were classified using the Ribosomal database project (RDP) and were submitted to the National Center for Biotechnology Information. Phylogenetic analysis using 16S rDNA sequences indicated that the 16 strains belonged to the Firmicutes (IK-MB6 Exiguobacterium aurantiacum, IK-MB7 Exiguobacterium arabatum, IK-MB8 Exiguobacterium arabatum, IK-MB9 Jeotgalibacillus alimentarius, IK-MB10 Bacillus megaterium, IK-MB11 Bacillus pumilus, IK-MB12 Bacillus pumilus, IK-MB13 Bacillus pumilus, IK-MB14 Bacillus megaterium), High GC, Gram-positive bacteria (IK-MB2 Micrococcus luteus, IK-MB5 Micrococcus luteus, IK-MB16 Arthrobacter mysorens), G-Proteobacteria (IK-MB3 Halomonas aquamarina, IK-MB15 Halotalea alkalilenta), CFB group bacteria (IK-MB1 Myroides odoratimimus), and Enterobacteria (IK-MB4 Proteus mirabilis). Among the 16 strains, representatives of the Firmicutes were dominant (56.25%) compared to the high GC, Gram-positive bacteria (18.75%), G-Proteobacteria (12.5%), CFB group bacteria (6.25%), and Enterobacteria (6.25%). Analysis revealed that majority of marine species found in marine biofilm are of anthropogenic origin.     

Geothermal springs in Armenia and Nagorno-Karabakh: potential sources of hydrolase-producing thermophilic bacilli

In recent years, scientists have increasingly focused on the microbial diversity of high-altitude hot springs to explore the biotechnological applications of extremophiles. In this regard, a total of 107 thermophilic bacilli were isolated from 9 high-altitude mineralized geothermal springs (of temperatures ranging from 27.5 to 70 °C) located within the territory of Armenia and Nagorno-Karabakh. The isolated bacilli were phylogenetically profiled and studied for their potential to produce extracellular hydrolytic enzymes (protease, amylase, and lipase). The identification of isolates based on 16S rRNA gene sequences revealed their relationship to members of more than 22 distinct species, of 8 different genera, namely Aeribacillus, Anoxybacillus, Bacillus, Brevibacillus, Geobacillus, Parageobacillus, Paenibacillus and Ureibacillus. Bacillus licheniformis, Parageobacillus toebii and Anoxybacillus flavithermus were found to be the most abundant species in the springs that were studied. Some of the isolated bacilli shared less than 91–97% sequence identity with their closest match in GenBank, indicating that Armenian geothermal springs harbor novel bacilli, at least at the species level. 71% of the isolates actively produced at least one or more extracellular proteases, amylases, or lipases. In total, 22 strains (28.6%) were efficient producers of all three types of thermostable enzymes.

     

A microdiversity study of anammox bacteria reveals a novel Candidatus Scalindua phylotype in marine oxygen minimum zones

The anaerobic oxidation of ammonium (anammox) contributes significantly to the global loss of fixed nitrogen and is carried out by a deep branching monophyletic group of bacteria within the phylum Planctomycetes. Various studies have implicated anammox to be the most important process responsible for the nitrogen loss in the marine oxygen minimum zones (OMZs) with a low diversity of marine anammox bacteria. This comprehensive study investigated the anammox bacteria in the suboxic zone of the Black Sea and in three major OMZs (off Namibia, Peru and in the Arabian Sea). The diversity and population composition of anammox bacteria were investigated by both, the 16S rRNA gene sequences and the 16S-23S rRNA internal transcribed spacer (ITS). Our results showed that the anammox bacterial sequences of the investigated samples were all closely related to the Candidatus Scalindua genus. However, a greater microdiversity of marine anammox bacteria than previously assumed was observed. Both phylogenetic markers supported the classification of all sequences in two distinct anammox bacterial phylotypes: Candidatus Scalindua clades 1 and 2. Scalindua 1 could be further divided into four distinct clusters, all comprised of sequences from either the Namibian or the Peruvian OMZ. Scalindua 2 consisted of sequences from the Arabian Sea and the Peruvian OMZ and included one previously published 16S rRNA gene sequence from Lake Tanganyika and one from South China Sea sediment (97.9-99.4% sequence identity). This cluster showed only 相似文献   

Extracellular hydrolytic enzyme screening of culturable heterotrophic bacteria from deep-sea sediments of the Southern Okinawa Trough

The Southern Okinawa Trough is an area of focused sedimentation due to particulate matter export from the shelf of the East China Sea and the island of Taiwan. In order to understand the geomicrobiological characteristics of this unique sedimentary environment, bacterial cultivations were carried out for an 8.61 m CASQ core sediment sample. A total of 98 heterotrophic bacterial isolates were characterized based on 16S rRNA gene phylogenetic analysis. These isolates can be grouped into four bacterial divisions, including 13 genera and more than 20 species. Bacteria of the γ-Proteobacteria lineage, especially those from the Halomonas (27 isolates) and Psychrobacter (20 isolates) groups, dominate in the culturable bacteria assemblage. They also have the broadest distribution along the depth of the sediment. More than 72.4% of the isolates showed extracellular hydrolytic enzyme activities, such as amylases, proteases, lipases and Dnases, and nearly 59.2% were cold-adapted exoenzyme-producers. Several Halomonas strains show almost all the tested hydrolases activities. The wide distribution of exoenzyme activities in the isolates may indicate their important ecological role of element biogeochemical cycling in the studied deep-sea sedimentary environment.     

Screening and isolation of halophilic bacteria producing extracellular hydrolyses from Howz Soltan Lake,Iran

Screening of bacteria from different areas of Howz Soltan playa, a hypersaline lake in the central desert zone of Iran, led to the isolation of 231 moderately halophilic bacteria, which were able to grow optimally in media with 5–15% of salt, and 49 extremely halophilic microorganisms that required 20–25% of salt for optimal growth. These isolates produced a great variety of extracellular hydrolytic enzymes. A total of 195, 177, 100, 95, 92, 68, 65, 33, and 28 strains produced lipases, amylases, proteases, inulinases, xylanases, cellulases, pullulanases, DNases, and pectinases, respectively. In comparison with gram-negative bacteria, the gram-positive halophilic rods, showed more hydrolytic activities. Several combined activities were showed by some of these isolates. One strain presented 9 hydrolytic activities, 4 strains presented 8 hydrolytic activities, 10 strains presented 7 hydrolytic activities and 29 strains presented 6 hydrolytic activities. No halophilic isolate without hydrolytic activity has been found in this study. According to their phenotypic characteristics and comparative partial 16S rRNA sequence analysis, the halophilic strains were identified as members of the genera: Salicola, Halovibrio, Halomonas, Oceanobacillus, Thalassobacillus, Halobacillus, Virgibacillus, Gracilibacillus, Salinicoccus, and Piscibacillus. Most lipase and DNase producers were members of the genera Gracilibacillus and Halomonas, respectively, whereas most of the isolates able to produce hydrolytic enzymes such as amylase, protease, cellulose (CMCase) and inulinase, belonged to gram-positive genera, like Gracilibacillus, Thalassobacillus, Virgibacillus, and Halobacillus.     

Isolation of lipid- and polysaccharide-degrading micro-organisms from subtropical forest soil, and analysis of lipolytic strain Bacillus sp. CR-179

AIMS: To isolate the micro-organisms from three soil samples obtained from a subtropical forest of Puerto Iguazu (Argentina), to analyse them for detection of the biotechnologically interesting enzymatic activities lipase, esterase, cellulase, xylanase and pectinase, and to identify the most active strain. METHODS AND RESULTS: A total of 724 strains were isolated using different culture media and temperatures, and 449 of them showed at least one of the hydrolytic activities pursued. Lipolytic activity of the lipid-degrading strains was further determined using MUF-butyrate and MUF-oleate as substrates. The alkalophilic strain CR-179, one of the most active for all the enzymatic activities assayed, was characterized and preliminarily identified by morphological, physiological and 16S rDNA tests, as a Bacillus sp. closely related to Bacillus subtilis. CONCLUSIONS: Highly hydrolytic strains were isolated from all soil samples, suggesting the existence of a microbial community well-adapted to nutrient recycling. Strain CR-179, one of the most active, has been preliminarily identified as a Bacillus sp. SIGNIFICANCE AND IMPACT OF THE STUDY: A collection of hydrolytic strains with high biotechnological potential was obtained. Presence of sequences codifying for a lipolytic system related to the B. subtilis group lipases was revealed by PCR for the best lipolytic strain.     

Diversity and biotechnological potential of culturable bacteria from Brazilian mangrove sediment

Mangrove ecosystems are environments subject to substantial degradation by anthropogenic activities. Its location, in coastal area, interfacing the continents and the oceans makes it substantially important in the prospection for biotechnological applications. In this study, we assessed the diversity of culturable bacteria present over the seasons at two depths (0–10 and 30–40 cm) in a mangrove sediment and in a transect area from the land to the sea. In total, 238 bacteria were isolated, characterized by Amplified Ribosomal DNA Restriction Analysis (ARDRA) and further identified, by Fatty Acid Methyl Esther (FAME-MIDI), into the orders of Vibrionales, Actinomycetales and Bacillales. Also the ability of the isolates in producing economically important enzymes (amylases, proteases, esterases and lipases) was evaluated and the order Vibrionales was the main enzymatic source.     

High Rate of Uptake of Organic Nitrogen Compounds by Prochlorococcus Cyanobacteria as a Key to Their Dominance in Oligotrophic Oceanic Waters

Direct evidence that marine cyanobacteria take up organic nitrogen compounds in situ at high rates is reported. About 33% of the total bacterioplankton turnover of amino acids, determined with a representative [³⁵S]methionine precursor and flow sorting, can be assigned to Prochlorococcus spp. and 3% can be assigned to Synechococcus spp. in the oligotrophic and mesotrophic parts of the Arabian Sea, respectively. This finding may provide a mechanism for Prochlorococcus' competitive dominance over both strictly autotrophic algae and other bacteria in oligotrophic regions sustained by nutrient remineralization via a microbial loop.     

16S rDNA sequence analysis of culturable marine biofilm forming bacteria from a ship's hull

Marine bacteria from the hull of a ship in the form of biofilms or microfouling were isolated, cultured, and identified by phylogenetic analysis using 16S rDNA sequences. With an average length of 946 bp, all the 16 sequences were classified using the Ribosomal database project (RDP) and were submitted to the National Center for Biotechnology Information. Phylogenetic analysis using 16S rDNA sequences indicated that the 16 strains belonged to the Firmicutes (IK-MB6 Exiguobacterium aurantiacum, IK-MB7 Exiguobacterium arabatum, IK-MB8 Exiguobacterium arabatum, IK-MB9 Jeotgalibacillus alimentarius, IK-MB10 Bacillus megaterium, IK-MB11 Bacillus pumilus, IK-MB12 Bacillus pumilus, IK-MB13 Bacillus pumilus, IK-MB14 Bacillus megaterium), High GC, Gram-positive bacteria (IK-MB2 Micrococcus luteus, IK-MB5 Micrococcus luteus, IK-MB16 Arthrobacter mysorens), G-Proteobacteria (IK-MB3 Halomonas aquamarina, IK-MB15 Halotalea alkalilenta), CFB group bacteria (IK-MB1 Myroides odoratimimus), and Enterobacteria (IK-MB4 Proteus mirabilis). Among the 16 strains, representatives of the Firmicutes were dominant (56.25%) compared to the high GC, Gram-positive bacteria (18.75%), G-Proteobacteria (12.5%), CFB group bacteria (6.25%), and Enterobacteria (6.25%). Analysis revealed that majority of marine species found in marine biofilm are of anthropogenic origin.     

Agarolytic culturable bacteria associated with three antarctic subtidal macroalgae

Bacterial communities of Antarctic marine macroalgae remain largely underexplored in terms of diversity and biotechnological applications. In this study, three Antarctic subtidal macroalgae (Himantothallus grandifolius, Pantoneura plocamioides and Plocamium cartilagineum), two of them endemic of Antarctica, were investigated as a source for isolation of agar-degrading bacteria. A total of 21 epiphytic isolates showed agarolytic activity at low temperature on agar plates containing agar as the sole carbon source. 16S rRNA identification showed that the agar-degrading bacteria belonged to the genera Cellulophaga, Colwellia, Lacinutrix, Olleya, Paraglaciecola, Pseudoalteromonas and Winogradskyella. The agarase enzyme from a potential new species of the genus Olleya was selected for further purification. The enzyme was purified from the culture supernatant of Olleya sp. HG G5.3 by ammonium sulfate precipitation and ion-exchange chromatography. Molecular weight of the agarase was estimated to be 38 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The purified enzyme exhibited activity at 4 °C, retaining >?50% of its maximum activity at this temperature. This is the first study reporting the phylogeny of agar-degrading bacteria isolated from Antarctic subtidal macroalgae and the results suggest the huge potential of Antarctic algae-associated bacteria as a source of cold-active hydrolytic enzymes of biotechnological interest.     

北戴河海洋沉积物中L-半胱氨酸脱硫细菌的多样性及其特性

【背景】脱硫细菌对有机硫的脱硫作用在硫的生物地球化学循环以及脱硫工业中都起着重要的作用。【目的】了解海洋沉积物中可分解有机物产生硫化氢的细菌多样性。【方法】对我国北戴河海洋沉积物中可培养的L-半胱氨酸脱硫细菌进行分离与筛选,通过对其16SrRNA基因序列测定与分析,构建系统发育树,并对其脱硫、脱氮能力进行检验。【结果】从海洋沉积物中分离得到97株细菌,从以L-半胱氨酸为硫源的培养基中筛选出62株有机脱硫专一型细菌。根据脱硫细菌的形态及其特征,从中选取12株作为典型代表做进一步分析,它们分别属于芽孢杆菌属(Bacillus)、赖氨酸芽孢杆菌属(Lysinibacillus)、动性球菌属(Planococcus)和红球菌属(Rhodococcus)。结果表明,这12株细菌均可产生半胱氨酸脱巯基酶,能够将半胱氨酸分解为丙酮酸、硫化氢和氨,即同时具备脱硫与脱氮的能力。其中有5株菌脱硫能力较强,分别属于赖氨酸芽孢杆菌属、动性球菌属和芽孢杆菌属。【结论】海洋沉积物中存在着丰富的L-半胱氨酸脱硫细菌,为进一步研究海洋中硫的生物地球化学循环提供了素材。     

Phytodegradation of the triphenylmethane dye Malachite Green mediated by cell suspension cultures of Blumea malcolmii Hook

Cell cultures of Blumea malcolmii Hook., developed in the laboratory, rapidly decolorized textile industry effluent along with a variety of dyes with diverse structural properties. Most rapid decolorization was observed in case of Malachite Green (93.41% decolorization within 24 h). The cells were capable of tolerating and degrading high concentrations of the dye, thus making them remarkable systems for phytoremediation studies. The enzymatic analysis during decolorization of Malachite Green showed the induction of enzymes such as laccase, veratryl alcohol oxidase and DCIP reductase indicating the involvement of these enzymes in the degradation of the dye. The cell cultures also mediated the remediation of textile industry effluent by bringing about a decrease in the BOD, COD and ADMI values of the effluent within 48 h. Phytotransformation was confirmed with the help of HPLC and the probable fate of metabolism of the dye was predicted with the help of GCMS analysis.     

Ability of Moderately Halophilic Bacteria to Control Grey Mould Disease on Tomato Fruits

Tomato is one of the leading crops in Tunisia in terms of weight consumed (20 kg/per person/year). Preserving the quality of the fruit from field to consumer is essential to successful marketing. Grey mould rot induced by Botrytis cinerea is an important cause of postharvest loss depending on season and handling practices. We describe here the ability of halotolerant to moderately halophilic bacteria isolated from different Tunisian Sebkhas (hypersaline soils) to protect fresh‐market tomato fruits from B. cinerea. The tomatoes tested were at two different stages of ripening, (i) mature‐green and (ii) red. Six strains significantly reduced growth of the pathogens from 67% to 87%. The effectiveness of these antagonists was also confirmed on green tomatoes; in which the fruit rot protection rate ranged from 74% to 100%. The antagonists were characterized by morphological, biochemical and physiological tests as well as 16S rDNA sequencing. The halotolerant effective isolates were identified as belonging to one of the species Bacillus subtilis (M1‐20, J9) or B. licheniformis (J24). One effective moderately halophilic isolate (M2‐26) was identified as Planococcus rifietoensis. These strains are a source of hydrolytic enzymes such as chitinases, proteases, laminarinases, amylases, lipases and cellulases. For comparison, 12 halotolerant or moderately halophilic strains obtained from DSM culture collection were also evaluated for their antifungal activity against B. cinerea on tomato fruits. The most effective strains were Halomonas subglaciescola, Halobacillus litoralis, Marinococcus halophilus, Salinococcus roseus, Halovibrio variabilis and Halobacillus halophilus with a percentage of grey mould rot reduction ranging from 71% to 97%. Inoculation of mature‐green tomatoes by the bacterial antagonist of Halobacillus trueperi resulted in no disease development. Our results indicate that the use of halotolerant to halophilic micro‐organisms should be helpful in reducing grey mould disease of stored tomatoes.