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We report here the production of an alkaline serine protease by Aspergillus flavus isolated at 5600-m depth from deep-sea sediments of the Central Indian Basin. When grown on defatted groundnut oil meal at 30 °C for 48–72 h, this fungal isolate produced 2000–2500 ACU mL−1 of alkaline protease. The purified protease had activity optima at pH 10.0 and 45 °C. It was a thiol-independent serine protease, identified as an alkaline serine protease ALP1 with a molecular mass of 42.57 kDa. The thermostability and activity of the enzyme increased at 60 °C, in the presence of additives such as sucrose, Tween 20, sorbitol, Ca2+ and glycerol and was not adversely affected by H2O2 indicating its potential as a detergent additive.

We report here the production of an alkaline serine protease by Aspergillus flavus isolated at 5600-m depth from deep-sea sediments of the Central Indian Basin. When grown on defatted groundnut oil meal at 30 °C for 48–72 h, this fungal isolate produced 2000–2500 ACU mL(−1) of alkaline protease. The purified protease had activity optima at pH 10.0 and 45 °C. It was a thiol-independent serine protease, identified as an alkaline serine protease ALP1 with a molecular mass of 42.57 kDa. The thermostability and activity of the enzyme increased at 60 °C, in the presence of additives such as sucrose, Tween 20, sorbitol, Ca(2+) and glycerol and was not adversely affected by H(2)O(2) indicating its potential as a detergent additive. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13205-020-02520-x) contains supplementary material, which is available to authorized users.

Liquid Chromatography–Mass Spectrometry-Quadrupole Time of Flight (LC/MS QToF) protein profiling of marine-derived Staphyloccous gallinarum NIOMR8 was carried out to evaluate proteins conferring chromate (Cr(6+)) resistance and possible metabolic pathways that were altered as a result. Expressional (up or down-regulation) responses to varying Cr(6+) (0, 50, 100, 150, and 200 µg mL(− 1)) concentrations varied, with as many as 346 proteins identified. Most number of proteins—their numbers in parentheses—were up-regulated when grown in medium with 50 µg mL(− 1) (162) and, down-regulated in medium with 100 (281) or 200 µg mL(− 1) Cr(6+) (280). Among these, eight proteins were commonly up-regulated, while 58 were commonly down-regulated across all conditions of Cr(6+). Expression of protein moieties in metabolic pathways like translation (38), transcription (14), replication (18) and repair (4), metabolism of carbohydrates (26), amino acids (27), nucleotides (17), and membrane transport (21) was evidenced. Up-regulation patterns suggest that reduction of molecular oxygen (5), DNA repair (4) and peptide misfolding (7) were the potential protective mechanisms employed to counter Cr(6+) stress. Additionally, proteins associated with biofilm and cell wall biogenesis highlight their hypothetical involvement in toxicity tolerance. Results also indicate that at higher concentrations of Cr(6+), down-regulation of functional proteins impedes normal cellular functions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13205-018-1522-6) contains supplementary material, which is available to authorized users.

Peptide mass fingerprinting of Gram-positive marine-derived Staphylococcus cohnii #NIOSBK35 gave us an insight into the proteins involved in conferring arsenic resistance as well as the probable metabolic pathways affected under metal stress. Analysis of the protein profiles obtained from LC/MS QToF (Liquid Chromatography-Mass Spectrometry-Quadrupole Time of Flight) resulted in the identification of 689 proteins. Further grouping of these proteins based on the arsenic concentration (0, 250, 500 and 850 ppm) and the time points (6, 9, 12, 18, 24 and 36 h) in growth phase showed that a total of 13 proteins were up-regulated, while 178 proteins were down-regulated across all the concentrations and time points. Arsenic specific proteins like arsenical pump-driving ATPase, ArsR family transcriptional regulator and arsenic operon resistance repressor were found to be highly up-regulated throughout all the conditions indicating their possible involvement in the tolerance to arsenic. MBL fold metallo-hydrolase, a known stress protein, was the only protein that was up-regulated at all time points across all arsenic concentrations. Metabolic pathways like translation, carbohydrate metabolism, amino acid metabolism, membrane transport, metabolism of cofactors and vitamins, replication and repair, nucleotide metabolism along with stress proteins and hypothetical proteins were found to be significantly expressed. Our results also suggest that arsenic stress at higher levels is negatively affecting the expression of many normal functional proteins required for cell survival.

Ten fungal isolates with an ability to degrade crude oil were isolated from select marine substrates, such as mangrove sediments, Arabian Sea sediments, and tarballs. Out of the ten isolates, six belonged to Aspergillus, two to Fusarium and one each to Penicillium and Acremonium as identified using ITS rDNA sequencing. The selected ten fungal isolates were found to degrade the long-chain n-alkanes as opposed to short-chain n-alkanes from the crude oil. Mangrove fungus #NIOSN-M126 (Penicillium citrinum) was found to be highly efficient in biodegradation of crude oil, reducing the total crude oil content by 77% and the individual n-alkane fraction by an average of 95.37%, indicating it to be a potential candidate for the development into a bioremediation agent.