Functional fibrillar interfaces: Biological hair as inspiration across scales

Hair, or hair-like fibrillar structures, are ubiquitous in biology, from fur on the bodies of mammals, over trichomes of plants, to the mastigonemes on the flagella of single-celled organisms. While these long and slender protuberances are passive, they are multifunctional and help to mediate interactions with the environment. They provide thermal insulation, sensory information, reversible adhesion, and surface modulation (e.g., superhydrophobicity). This review will present various functions that biological hairs have been discovered to carry out, with the hairs spanning across six orders of magnitude in size, from the millimeter-thick fur of mammals down to the nanometer-thick fibrillar ultrastructures on bateriophages. The hairs are categorized according to their functions, including protection (e.g., thermal regulation and defense), locomotion, feeding, and sensing. By understanding the versatile functions of biological hairs, bio-inspired solutions may be developed across length scales.

Three ancient documents solve the jigsaw of the parchment purple spot deterioration and validate the microbial succession model

The preservation of cultural heritage is one of the major challenges of today's society. Parchments, a semi-solid matrix of collagen produced from animal skin, are a significant part of the cultural heritage, being used as writing material since ancient times. Due to their animal origin, parchments easily undergo biodeterioration: the most common biological damage is characterized by isolated or coalescent purple spots, that often lead to the detachment of the superficial layer and the consequent loss of written content. Although many parchments with purple spot biodegradative features were studied, no common causative agent had been identified so far. In a previous study a successional model has been proposed, basing on the multidisciplinary analysis of damaged versus undamaged samples from a moderately damaged document. Although no specific sequences were observed, the results pointed to Halobacterium salinarum as the starting actor of the succession. In this study, to further investigate this topic, three dramatically damaged parchments were analysed; belonging to a collection archived as Faldone Patrizi A 19, and dated back XVI-XVII century A.D. With the same multidisciplinary approach, the Next Generation Sequencing (NGS, Illumina platform) revealed DNA sequences belonging to Halobacterium salinarum; the RAMAN spectroscopy identified the pigment within the purple spots as haloarchaeal bacterioruberin and bacteriorhodopsine, and the LTA technique quantified the extremely damaged collagen structures through the entire parchments, due to the biological attack to the parchment frame structures. These results allowed to propose a model of the progressive degradation pattern of the parchment collagen. Overall, these data validate a multi-phase microbial succession model. This demonstration is pivotal to possible new restoration strategies, important for a huge number of ancient documents.

Approach toward enhancement of halophilic protease production by Halobacterium sp. strain LBU50301 using statistical design response surface methodology

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Halophilic protease producing Halobacterium sp. strain LBU50301 was isolated.

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RSM optimized the fermentation conditions to enhance halophilic protease yield.

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Optimized conditions used in bioreactor resulted about 13-fold enhancement.

A new potent halophilic protease producer, Halobacterium sp. strain LBU50301 was isolated from salt-fermented fish samples (budu) and identified by phenotypic analysis, and 16S rDNA gene sequencing. Thereafter, sequential statistical strategy was used to optimize halophilic protease production from Halobacterium sp. strain LBU50301 by shake-flask fermentation. The classical one-factor-at-a-time (OFAT) approach determined gelatin was the best nitrogen source. Based on Plackett–Burman (PB) experimental design; gelatin, MgSO₄·7H₂O, NaCl and pH significantly influenced the halophilic protease production. Central composite design (CCD) determined the optimum level of medium components. Subsequently, an 8.78-fold increase in corresponding halophilic protease yield (156.22 U/mL) was obtained, compared with that produced in the original medium (17.80 U/mL). Validation experiments proved the adequacy and accuracy of model, and the results showed the predicted value agreed well with the experimental values. An overall 13-fold increase in halophilic protease yield was achieved using a 3 L laboratory fermenter and optimized medium (231.33 U/mL).

Exploring the multiple biotechnological potential of halophilic microorganisms isolated from two Argentinean salterns

The biodiversity and biotechnological potential of microbes from central Argentinean halophilic environments have been poorly explored. Salitral Negro and Colorada Grande salterns are neutral hypersaline basins exploded for NaCl extraction. As part of an ecological analysis of these environments, two bacterial and seven archaeal representatives were isolated, identified and examined for their biotechnological potential. The presence of hydrolases (proteases, amylases, lipases, cellulases and nucleases) and bioactive molecules (surfactants and antimicrobial compounds) was screened. While all the isolates exhibited at least one of the tested activities or biocompounds, the species belonging to Haloarcula genus were the most active, also producing antimicrobial compounds against their counterparts. In general, the biosurfactants were more effective against olive oil and aromatic compounds than detergents (SDS or Triton X-100). Our results demonstrate the broad spectrum of activities with biotechnological potential exhibited by the microorganisms inhabiting the Argentinean salterns and reinforce the importance of screening pristine extreme environments to discover interesting/novel bioactive molecules.

Halocalculus aciditolerans gen. nov., sp. nov., an acid-tolerant haloarchaeon isolated from commercial salt

Three halophilic archaeal strains, MH2-243-1T, MH2-93-1 and MH2-91-1 were isolated from commercial salt samples from Japan, Australia, and Bolivia. Strain MH2-243-1T was able to grow in the presence of 12–30 % (w/v) NaCl (optimum, 18 % NaCl), at pH 4.5–7.0 (optimum, pH 6.0) and at 20–60 °C (optimum, 40 °C). Strains MH2-91-1 and MH2-93-1 grew in slightly different ranges. The orthologous 16S rRNA gene sequences of the three strains were almost identical (99.8–99.9 % similarities), and the closest relative was Salarchaeum japonicum JCM 16327T with 94.2–94.3 % 16S rRNA gene sequence similarities, followed by strains of members of the closely related genera Halobacterium and Halarchaeum . The RNA polymerase subunit B′ gene (rpoB′) sequence also showed the highest similarity (86.6 %) to that of Salarchaeum japonicum JCM 16327T. The DNA G+C contents of strains MH2-243-1T, MH2-93-1 and MH2-91-1 were 68.5, 68.8 and 68.3 mol%, respectively. DNA–DNA relatedness values amongst the three strains were 97–99 %. The polar lipids of the three strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, and at least seven unidentified glycolipids. The polar lipid composition differed from those of Salarchaeum japonicum and species of the genera Halobacterium and Halarchaeum . Based on the phenotypic and phylogenetic analyses, it is proposed that the isolates represent a novel species of a new genus, for which the name Halocalculus aciditolerans gen. nov., sp. nov. is proposed. The type strain of the type species is MH2-243-1T ( = JCM 19596T = KCTC 4149T) isolated from solar salt produced in Japan. MH2-93-1 ( = JCM 19595) and MH2-91-1 ( = JCM 19594) are additional strains of the type species.

Halophilic archaea cultivated from surface sterilized middle-late eocene rock salt are polyploid

Live bacteria and archaea have been isolated from several rock salt deposits of up to hundreds of millions of years of age from all around the world. A key factor affecting their longevity is the ability to keep their genomic DNA intact, for which efficient repair mechanisms are needed. Polyploid microbes are known to have an increased resistance towards mutations and DNA damage, and it has been suggested that microbes from deeply buried rock salt would carry several copies of their genomes. Here, cultivable halophilic microbes were isolated from a surface sterilized middle-late Eocene (38–41 million years ago) rock salt sample, drilled from the depth of 800 m at Yunying salt mine, China. Eight unique isolates were obtained, which represented two haloarchaeal genera, Halobacterium and Halolamina. We used real-time PCR to show that our isolates are polyploid, with genome copy numbers of 11–14 genomes per cell in exponential growth phase. The ploidy level was slightly downregulated in stationary growth phase, but the cells still had an average genome copy number of 6–8. The polyploidy of halophilic archaea living in ancient rock salt might be a factor explaining how these organisms are able to overcome the challenge of prolonged survival during their entombment.

Halobacterium piscisalsi Yachai et al. 2008 is a later heterotypic synonym of Halobacterium salinarum Elazari-Volcani 1957

Halobacterium piscisalsi was proposed by Yachai et al. (2008), with a single strain, HPC1-2T ( = BCC 24372T  = JCM 14661T  = PCU 302T), which was isolated from fermented fish (pla-ra) in Thailand. According to Yachai et al. (2008), the strain was closely related to Halobacterium salinarum based on 16S rRNA gene sequence comparisons and could be differentiated by low DNA–DNA relatedness values and different biochemical profiles compared with other species of the genus. The reanalysis of the 16S rRNA gene sequences and the DNA–DNA relatedness among H. piscisalsi JCM 14661T and H. salinarum strains JCM 8978T, R1 and NRC-1 revealed that they all had exactly the same 16S rRNA gene sequence and shared more than 70 % DNA–DNA relatedness. In addition, the full-length DNA-dependent RNA polymerase subunit B (RpoB) protein sequence of H. piscisalsi JCM 14661T (607 amino acids) was the same as that of H. salinarum JCM 8978T and showed 94.7 and 96.7 % similarities with those of Halobacterium noricense JCM 15102T and Halobacterium jilantaiense JCM 13558T, respectively. Despite the different biochemical properties described by Yachai et al. (2008), the characteristic phenotypic properties of H. piscisalsi agreed with those in the description of H. salinarum emended by Gruber et al. (2004). Therefore, H. piscisalsi Yachai et al. (2008) should be regarded as a later heterotypic synonym of H. salinarum Elazari-Volcani 1957.

Taxonomy of the family Halobacteriaceae: a paradigm for changing concepts in prokaryote systematics

The halophilic Archaea of the family Halobacteriaceae (36 genera with 129 species with standing in nomenclature as of November 2011) provide an excellent example of how changing concepts on prokaryote taxonomy and the development of new methods have influenced the way in which the taxonomy of a single group of prokaryotes is treated. This review gives an overview of the taxonomy of the family Halobacteriaceae, showing the impact that methods of phenotypic characterization, numerical taxonomy, chemotaxonomy and especially polar lipid analysis, 16S rRNA gene sequence comparisons, multilocus type analysis and comparative genomics have had on their classification.

Salinarchaeum laminariae gen. nov., sp. nov.: a new member of the family Halobacteriaceae isolated from salted brown alga Laminaria

Halophilic archaeal strains R26(T) and R22 were isolated from the brown alga Laminaria produced at Dalian, Liaoning Province, China. Cells from the two strains were pleomorphic rods and Gram negative, and colonies were red pigmented. Strains R26(T) and R22 were able to grow at 20-50°C (optimum 37°C) in 1.4-5.1 M NaCl (optimum 3.1-4.3 M) at pH 5.5-9.5 (optimum pH 8.0-8.5) and neither strain required Mg(2+) for growth. Cells lyse in distilled water and the minimum NaCl concentration required to prevent cell lysis was 8% (w/v) for strain R26(T) and 12% (w/v) for strain R22. The major polar lipids of the two strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and minor phosphatidylglycerol sulfate; glycolipids were not detected. Phylogenetic analyses based on 16S rRNA genes and rpoB' genes revealed that strains R26(T) and R22 formed a distinct clade with the closest relative, Natronoarchaeum mannanilyticum. The DNA G+C content of strains R26(T) and R22 was 65.8 and 66.4 mol%, respectively. The DNA-DNA hybridization value between strains R26(T) and R22 was 89%. The phenotypic, chemotaxonomic and phylogenetic properties suggest that the strains R26(T) and R22 represent a novel species in a new genus within the family Halobacteriaceae, for which the name Salinarchaeum laminariae gen. nov., sp. nov. is proposed. The type strain is R26(T) (type strain R26(T) = CGMCC 1.10590(T) = JCM 17267(T), reference strain R22 = CGMCC 1.10589).

Halomarina oriensis gen. nov., sp. nov., a halophilic archaeon isolated from a seawater aquarium

A novel halophilic archaeon, strain KeC-11T, was isolated from a seawater aquarium at the Ocean Research Institute, University of Tokyo, Japan. The strain was aerobic, Gram-negative and chemo-organotrophic, growing optimally at 37 °C, at pH 7.0–8.0 and in 2.7 M (16 %) NaCl. The strain required at least 10 mM magnesium ions for growth. Cells of strain KeC-11T were non-motile and generally irregular coccoids or discoids. The DNA G+C content of the isolate was 67.7 mol%. Phylogenetic tree reconstructions indicated that it was distantly related to the other recognized members of the family Halobacteriaceae, with the closest relative being Natronomonas pharaonis GabaraT (91 % sequence similarity). The strain contained C20C20 and C20C25 diether derivatives of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, a glycolipid chromatographically identical to the glycosyl-mannosyl-glucosyl diether (TGD-2) and at least one unidentified glycolipid. Phenotypic characterization and phylogenetic data support the placement of isolate KeC-11T in a novel species in a new genus within the family Halobacteriaceae, for which the name Halomarina oriensis gen. nov., sp. nov. is proposed; the type strain is KeC-11T ( = JCM 16495T  = KCTC 4074T).

Could halophilic archaea improve the traditional salted anchovies (Engraulis encrasicholus L.) safety and quality?

AIMS

The positive influence of two selected extremely halophilic archaea strains in the production of salted anchovies (Engraulis encrasicolus, L., 1758) was highlighted.

METHODS AND RESULTS

Anchovies produced with salt artificially contaminated with halophiles exhibited lower loads of staphylococci, Enterobacteriaceae and lactic acid bacteria, and a reduced content of histamine as well as an improved organoleptic acceptance.

CONCLUSIONS

The findings of this survey are expected to enhance the safety of salted anchovies, with regard to the histamine formation during ripening, and to improve the sensory attributes of this product.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study represents the first report on the positive influence of halophilic archaea in traditional salted anchovies production, thus suggesting new perspectives about a conscious employment of properly selected haloarchaea strains in this traditional manufacture.

Salarchaeum japonicum gen. nov., sp. nov., an aerobic, extremely halophilic member of the Archaea isolated from commercial salt

Strain YSM-79(T) was isolated from commercial salt made from seawater in Yonaguni island, Okinawa, Japan. The strain is an aerobic, Gram-negative, chemo-organotrophic and extremely halophilic archaeon. Cells are short rods that lyse in distilled water. Growth occurs at 1.5-5.3 M NaCl (optimum 2.5-3.0 M), pH 5.0-8.8 (optimum pH 5.2-6.3) and 20-55 °C (optimum 40 °C). Mg²⁺ is required for growth, with maximum growth at 200-300 mM Mg²⁺. Polar lipid analysis revealed the presence of phosphatidylglycerol, phosphatidylglycerophosphate methyl ester, sulfated diglycosyl diether-1 and five unidentified glycolipids. The G+C content of the DNA was 64 mol%. On the basis of 16S rRNA gene sequence analysis, strain YSM-79(T) was determined to be a member of the family Halobacteriaceae, with the closest related genus being Halobacterium (94 % sequence identity). In addition, the rpoB' gene sequence of strain YSM-79(T) had <88 % sequence similarity to those of other members of the family Halobacteriaceae. The results of phenotypic, chemotaxonomic and phylogenetic analysis suggested that strain YSM-79(T) should be placed in a new genus, Salarchaeum gen. nov., as a representative of Salarchaeum japonicum sp. nov. The type strain is YSM-79(T) ( = JCM 16327(T)  = CECT 7563(T)).

Halarchaeum acidiphilum gen. nov., sp. nov., a moderately acidophilic haloarchaeon isolated from commercial solar salt

A novel halophilic archaeon, strain MH1-52-1(T), was isolated from solar salt imported from Australia. Cells were pleomorphic, non-motile and Gram-negative. Strain MH1-52-1(T) required at least 3.0 M NaCl and 1 mM Mg(2+) for growth. Strain MH1-52-1(T) was able to grow at pH 4.0-6.0 (optimum, pH 4.4-4.5) and 15-45 °C (optimum, 37 °C). The diether phospholipids phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester, derived from both C(20)C(20) and C(20)C(25) archaeol, were present. Four unidentified glycolipids were also detected. The 16S rRNA gene sequence showed the highest similarity to that of Halobacterium noricense A1(T) (91.7%); there were lower levels of similarity to other members of the family Halobacteriaceae. The G+C content of its DNA was 61.4 mol%. Based on our phenotypic, genotypic and phylogenetic analyses, it is proposed that the isolate should be classified as a representative of a new genus and species, for which the name Halarchaeum acidiphilum gen. nov., sp. nov. is proposed. The type strain of Halarchaeum acidiphilum is MH1-52-1(T) (=JCM 16109(T) =DSM 22442(T) =CECT 7534(T)).