Diversity and extracellular enzyme activities of heterotrophic bacteria from sediments of the Central Indian Ocean Basin

Abstract

Sedimentary bacteria play a role in polymetallic nodule formation and growth. There are, however, limited reports on bacterial diversity in nodule-rich areas of the Central Indian Ocean Basin (CIOB). In this study, bacterial abundance in thirteen sediment cores collected from the CIOB was enumerated, followed by phylogenetic characterisation and, screening of select heterotrophic bacteria for extracellular enzyme activities. Total bacterial counts (TBC) were in the order of 10 7 cells g −1 ; there was a significant difference (p > 0.05) among the cores but not within the sub-sections of the cores. The retrievable heterotrophic counts ranged from non-detectable to 5.33 × 10 5 g −1 ; the heterotrophic bacteria clustered within the phyla Firmicutes, Proteobacteria and Actinobacteria. Bacillus was the most abundant genus. The extracellular enzyme activities were in the order: amylase > lipase > protease > phosphatase > Dnase > urease. Major findings are compared with previous studies from the CIOB and other areas.

Response and Adaptation of Microbial Community in a CANON Reactor Exposed to an Extreme Alkaline Shock

“…Bacillus is a robust model organism for biofilm formation [ 51 ]. Bacillus can not only contribute to O 2 removal [ 52 ], nitrate reduction [ 53 ], and organic matter degradation [ 54 ] but can also secrete EPS, especially EPS-PN, for increasing resistances to adverse environmental stresses [ 55 ]. All these factors may explain why the Bacillus survived after alkaline shock.…”

Caracterización de bacterias cultivables aisladas de sitios de arrecifes mesofóticos de Cuba

“…Las bacterias heterótrofas evaluadas también fueron capaces de producir diferentes enzimas hidrolíticas, independientemente de los niveles de la columna de agua, similar a lo informado para diferentes ecosistemas marinos (Liu et al 2018;Gawas et al 2019). Resulta interesante la marcada incidencia de cultivos de las aguas profundas con alta actividad enzimática, probablemente relacionada con la naturaleza de compuestos de alto peso molecular y polímeros como proteínas, almidón, ácidos nucleicos, lípidos complejos, entre otros (Arnosti, 2014;Dang & Lovell, 2016).…”

“…Entre los grupos fenotípicos más representados para ambos niveles de los sitios mesofóticos se destacan los bacilos G+ esporulados; donde se incluye el género Bacillus, reconocido como productores de diferentes exoenzimas (Odisi et al 2012;Lailaja & Chandrasekaran, 2013;Gawas et al 2019;Jin et al 2019).…”

“…El predominio del género Bacillus entre los aislados de ambos niveles de la columna de agua, debe estar relacionado con la amplia distribución de este grupo en diferentes ecosistemas marinos, ya que este género se caracteriza por presentar esporas como estructura de resistencia y supervivencia ante cambios ambientales; así como una alta versatilidad metabólica para su adaptación a las condiciones extremas (Izadpanah Qeshmi et al 2018;Gawas et al 2019). También Lugioyo et al (2010) refirieron un predominio de la familia Bacillaceae, específicamente al género Bacillus, en muestras de aguas oceánicas adyacentes a Cuba.…”

Bacterial and Fungal Diversity in Sediment and Water Column From the Abyssal Regions of the Indian Ocean

“…In recent times, researchers have focused on isolation, cultivation and screening of deep-sea microbes for biotechnological applications. Aiming to identify bacteria with potential biotechnological applications, Gawas et al (2019) isolated 43 heterotrophic bacteria belonging to the phyla Proteobacteria, Actinobacteria, and Firmicutes, from nodule associated sediments of the first generation mining site and preservation reference zone of the CIOB. This is among the first reports of Oceanobacillus (Firmicutes) and Brachybacterium (Actinobacteria) in the CIOB, although these genera have been previously reported from deep-sea sediments of the Pacific and the Atlantic Oceans.…”