Isolation of bacteria from the corallum of Porites lobata (Vaughn) and its possible significance

Abstract

Bacteria were recovered from loci within skeletal regions of the glomerate coral,Porites lobata. The origin of these bacteria is unknown, although areas of discoloration suggest invasion from the substratum in the region of basal attachment. Weakened areas of internal corallum contained from 104 to 105 bacteria per gram dry weight as determined by plate counts on a peptone-agar medium. Some of the isolated bacteria were capable of digesting chitin in vitro. This rinding suggested that the mechanism for skeletal weakening might be bacterial breakdown of the organic matrix. Absence of change from aragonitic to calcitic crystals from a discolored region supported the contention that skeletal weakening was due to the breakdown of organic matrix rather than dissolution of carbonate.Results were obtained as part of a survey to determine the number and distribution of bacteria in some coral reef environments. © 1969 by the American Society of Zoologists.